Oral Presentations - abstracts

Monday, April 8, 2002

Plenary Lecture

Whole grain foods are those that include bran, germ, and endosperm, rather than only endosperm, of a variety of grains. Consumption of whole grain foods is often associated with other healthy dietary and lifestyle behaviors. Habitual whole grain eaters have a 50% reduction in risk for total mortality and for coronary heart disease, diabetes, and total cancer, compared to those who eat only refined grain. Holding other health behaviors constant, risk reductions associated with whole grain consumption are about 20%. Yet, whole grain consumption is unrelated to total mortality in an ecologic study. Similar statements can be made about other plant foods: fruit, vegetables, nuts, legumes, and spices appear to protect against a variety of chronic diseases. It appears that consumption of a variety of plant foods, as in the Seventh Day Adventist, Mediterranean, and DASH diets, is efficacious in reducing chronic disease risk. Components of these plant foods are likely to act synergistically in providing protection. Study of individual phytochemicals is likely to miss synergies. A top-down approach to research serially examines biological outcomes in whole foods, food parts, food extracts, and individual food constituents. Such an approach is likely to enhance understanding of nutritional effects of plant foods.

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Food is no longer viewed as simply a vehicle to supply calories, macronutrients, and micronutrients. It is increasingly and additionally recognized as a plethora of non-nutrient substances that promote better health and help prevent chronic diseases such as cardiovascular disease and cancer. These phytochemicals are found in a variety of plant foods (vegetables, fruit, legumes, whole grains, herbs, nuts and seeds) and belong to a myriad of different families. They include shikimic acid metabolites, isoprenoid metabolites, oligosaccharides and polysaccharides, sulfur-containing compounds, and other antioxidant compounds. Research has focused on identifying the active phytochemicals found in the different functional foods and the mechanism by which they function to provide the health-promoting properties. The issue is debated as to whether the isolated phytochemicals (nutraceuticals) provide the same physiological activity as the whole food containing the phytochemicals. Clinical trials examining the physiological effects of lycopene, beta-carotene, isoflavones, phytosterols, tocotrienols, trans-resveratrol, and other phytochemical supplementation, have met with mixed and sometimes disappointing results. Additional research is needed to establish the mechanisms of action, the dose-response relationships, the stability of the extracts, the necessary matrix for optimal function, and the synergistic effects between the phytochemicals.

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Research and, consequently, recommendations concerning healthy nutrition are usually based on single nutrients or on food items/food groups. However, the impact of diet as a whole is much more complex. Studies with populations on their habitual diet (western type diet, diet considering preventive plant-centered recommendations, raw food diet, vegan diet) show that simply considering food consumption or nutrient intake does not allow any conclusion on the supply with a specific nutrient or the level of risk or preventive factors. Therefore, when examining the complete diets, unexpected blood concentrations are observed. This may be the result of combinations and/or of the sum of various effects that are too small to be statistically significant. The evaluation of nutrients (and the respective blood parameters) gives further evidence that parts of a diet do not add up to a whole. A favorable nutrient supply can neither be guaranteed with a certain intake of a nutrient, nor with the consumption of a certain amount of food items providing this nutrient. However, a favorable nutrient supply and/or optimal levels of risk or preventive factors are attainable with certain dietary patterns. Therefore, research and the recommendations deriving thereof should be based on diet as a whole.

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Cardiovascular disease and cancer are ranked the first and second respectively as the leading causes of death in the United States and the most industrialized countries. Regular consumption of fruits and vegetables is associated with reduced risks of cancer, cardiovascular disease, stroke, Alzheimer’s disease, cataract and some of the functional declines associated with aging. Prevention is a more effective strategy than treatment for chronic diseases. Functional foods that contain significant amounts of bio-active components may provide desirable health benefits beyond basic nutrition and is a practical strategy for the prevention of chronic diseases. Our group found that the antioxidant activity of the vitamin C in apples with skin accounts for only 0.4% of the total antioxidant activity, suggesting the majority of antioxidant activity of fruits and vegetables may come from phenolics and flavonoids. We proposed that the additive and synergistic effects of phytochemicals in fruits and vegetables are responsible for their potent antioxidant and anticancer activities, and that the benefit of a diet rich in fruits and vegetables is attributed to the complex mixture of phytochemicals present in whole foods. This presentation will cover our current research on the health benefits of phytochemicals, and focus on the additive and synergistic effects of phytochemicals in the regulation of gene expression, and their potential applications in functional foods. This data provides convincing evidence about the phytochemicals in the prevention of chronic diseases, and encourages consumers to change their dietary behaviors for health improvement and disease prevention.

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A number of historical references have been made to isolated rural peoples who purportedly experienced greater longevity due to the low meat content of their diet. More recently, increased life expectancy and decreased coronary heart disease mortality rates have been reported in countries with lower national consumption levels of animal products. Does low meat consumption contribute to greater longevity? When considering this question in a scientific context, it is important to note that the apparently supportive historical reference and patterns in national consumption data do not have sufficient methodology to be conclusive. In this presentation, I have addressed this question by examining the current epidemiologic findings from prospective cohort studies of adults that have related very low meat intake and very low meat intake diet patterns to all-cause mortality. Implications of the current evidence, limitation of the current evidence, and further lines of inquiry are discussed.

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Three prospective studies have been set up to study the long-term health and mortality of vegetarians in Britain. The Health Food Shoppers Study and the Oxford Vegetarian Study were established in the 1970s and 1980s respectively; each included about 11,000 subjects and used a relatively short questionnaire. The EPIC-Oxford cohort was established in the 1990s, and includes about 60,000 subjects who completed a detailed food frequency questionnaire, as well as 20,000 blood samples and 30,000 seven-day food diaries. The findings of the two earlier studies will be summarized, and the preliminary results from the new EPIC-Oxford cohort described. In general, the mortality rates of all the subjects in all three studies are much lower than average for the UK, showing that the health of both the vegetarians and the meat-eaters in these studies is good. Comparisons of vegetarians with meat-eaters within the studies show only small differences in total mortality rates, but in all three studies mortality from ischaemic heart disease is 15-20% lower in vegetarians. The interpretation of these data will be discussed in relation to the dietary and lifestyle characteristics of the vegetarians in these studies.

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Nutritional interventions, in this case, increasing dietary intake of fruits and vegetable, can retard and even reverse age-related declines in brain function and in cognitive and motor performance in rats. Our lab has shown that as Fischer 344 rats age, their brains are increasingly vulnerable to oxidative stress. Dietary supplementation with fruit or vegetable extracts high in antioxidants (e.g., blueberry, BB, spinach, respectively) can decrease this vulnerability to oxidative stress as assessed in vivo by examining (reductions in neuronal signaling and behavioral deficits) and in vitro via H 2O 2-induced decrements in striatal synaptosomal calcium buffering. Examinations have also revealed that BB-supplementations (S) are very effective in antagonizing the age-related changes in neuronal signaling and behavior, as well as improving both anti-oxidant and anti-inflammatory activity in the tissue. For example, as has been seen with respect to caloric restriction, BB supplementation has restored an important heat shock protein response(HSP-70) response in the hippocampus (an important memory control area) in old animals. In ongoing studies we are attempting to determine the most effective BB polyphenolic components. To date, the anthocyanins show the most efficacy in penetrating the cell membrane, and in providing antioxidant and anti-inflammatory protection. We also now have evidence to show that some of the polyphenolics are found in the brains of the supplemented animals (e.g., malvidin-3-glucoside) In addition, determinations are also being made to assess the effects of these polyphenolic compounds on signaling molecules involved in learning and memory. However, it is clear that increasing dietary intake of fruits and vegetables high in antioxidant activity may be an important component of a healthy living strategy designed to maximize neuronal and cognitive functioning into old age.

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It was the purpose of the present study to compare health and physical fitness status in a group of vegetarian (V) and non-vegetarian (NV) seniors. Subjects: 23 female and 7 male NV aged >65 years (female: 84.3 " 5 yrs, male: 80.6 " 7.3 yrs) and 22 female and 7 male V aged >65 years (female: 84.1 " 5.1 yrs, male: 80.5 " 7.5 yrs). The V group lived in a home for elderly vegetarians, and the NV-group in an ordinary elderly home. Medical history, dietary analysis, blood profile, anthropometric parameters, and physical fitness assessment were registered. The general questionnaire revealed a lower morbidity in the V group compared to the NV, with lower use of medication (51.9%) in the V group compared to the NV (76,7%). Seventy five percent of the V group and 63.3% of the NV did not use alcohol at all. Mean daily energy intake of 8.0 MJ was just above the recommended intake (7.8 MJ) for the NV females, whereas the V females with 6.8 MJ did not reach the recommended value. Both male V and NV groups had a mean daily energy intake of 8.7 MJ reaching almost the recommended value of 8.8 MJ. The mean values for carbohydrate intake were too low (V: 47.9 " 7.0. E %, NV: 42.8 " 4.1. E %), for protein, too high (V: 17.5 " 3.4 E %, NV: 20.3 " 2.7 E %), while fat intake (V: 33.7 " 7.5 E %, NV: 33.9 " 3.7 E %) was slightly high. Mean vitamin and mineral intake was in both groups above the RDA. Blood analysis showed normal vitamin B12, Folic acid, Fe, and Ca concentrations for both groups. The Zn blood serum concentrations did not reach the reference value in both groups, in contrast to Zn intake measured with the FFQ. Mean cholesterol concentration was below the 200 mg/dl upper limit in the NV (181.5 " 45.1 mg/dl) group and above that limit in the V group (212.6 " 39.8 mg/dl). Physical performance: strength tests scored under the reference values in both groups. Our experience showed the need for an appropriate test to measure the endurance capacity in this age group. Anthropometric profile: mean BMI was 26.8 ± 3.7 kg/m 2 for the female NV subjects, 26.1 ± 4.7 kg/m 2 for the female V subjects, 25.2 ± 4.2 kg/m 2 for the male NV subjects and 23.5 ± 3.7 kg/m 2 for the male V subjects .

Comparing vegetarian and non-vegetarian seniors, our results show a similar profile for both groups concerning, nutritional intake (except for the energy intake between the female groups), blood values (except for cholesterol), physical performance capacity and body composition (except for males BMI).

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Dr. Kerstetter will summarize the importance of dietary protein on maintaining normal calcium homeostasis and bone health in adult men and women. Work from her laboratory has demonstrated that dietary protein exerts a profound and generally under-appreciated effect on calcium homeostasis. Studies conducted in over 90 men and women have consistently found that low protein diets reduce intestinal calcium absorption resulting in significant secondary hyperparathyroidism and elevations in kinetic rates of bone turnover. These acute studies are conducted over a 4-14 day period where the low protein diet is defined as 0.7 g protein/kg body weight. Analysis of available data from the U.S. Department of Agriculture indicates that approximately 30% of adult women consume protein at a level below the RDA (0.8 g protein/kg). Therefore if the acute results reflect chronic changes induced by low levels of protein intake, there are a substantial number of American women with protein intakes inadequate to support normal calcium metabolism. In contrast, high protein diets cause hypercalciuria due, in part, to increased intestinal calcium absorption. Her studies suggest that diets that are too low in protein have a negative impact on calcium metabolism and potentially, on skeletal health.

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Interest in the role of phytoestrogens, and in particular the soybean isoflavones in protecting against osteoporosis has been driven by the continued search for alternative therapeutic strategies to the ‘gold-standard’ use of estrogen replacement therapy. Promising initial results with a synthetic isoflavone, called Ipriflavone, approved in some countries for the prevention of bone loss led to investigations of soybean isoflavones as candidate molecules. Impressive data from studies on cultured bone cells, and rat models of postmenopausal osteoporosis support a significant bone-sparing effect of the isoflavones, genistein and daidzein. Translating this research to the clinic has been slow and thus far only a few clinical studies have attempted to examine the effectiveness of phytoestrogens-rich diets, with promising although mixed results. These studies have been mostly of short duration (<6 months) and biostatistically powered low, making it difficult to observe significant changes in bone. Optimal isoflavone intakes remain to be determined. Clinical studies can be broadly divided into those that have looked for biochemical evidence of reduced postmenopausal bone turnover from measurement of surrogate markers, and those that have examined changes in bone mineral density (BMD). There have been no long-term studies to determine the overall effectiveness of a phytoestrogen-rich diet on fracture rate, the ultimate gold-standard measure of efficacy. Our research has confirmed that a diet delivering 60-70 mg of isoflavones delivered in the form of soy milk or soy nuts quickly reduces urinary cross-linked N-telopeptides of type I collagen loss and increases serum osteocalcin levels. More recently, we performed, a 2-year study of 108 postmenopausal women randomized to receive a two glasses of soymilk per day that either contained high levels of isoflavones or negligible levels of isoflavones. The results of this study showed that the women who consumed soy with isoflavones maintained stable lumbar spine BMD after 2 years, while those consuming the same amount of soy milk with negligible isoflavone levels lost almost 5% of their lumbar spine BMD; as would be anticipated in untreated natural menopause. These effects were not related to dietary calcium of protein composition. More interestingly, we have found that the extent of intestinal metabolism of isoflavones may be the single most important clue to the clinical efficacy of soy foods in preventing bone loss. Equol, a specific bacterial metabolite of daidzein, and not found in soy, was formed in only 45% of the women, but in those that did make equol, referred to as ‘equol producers’ lumbar spine BMD increased by 2.4%, significantly greater than women who could not make equol. Equol has a much higher affinity for the estrogen receptor than daidzein, its precursor phytoestrogen and this probably explains the greater effects observed in ‘equol producers’. The ability to ‘bacteriotype’ individuals for their ability to produce equol seems crucial in the design of future clinical studies of soy foods and this may be an explanation for the variances in data reported among previous studies of phytoestrogens and bone.

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In 1976, 30198 white, non-hispanic California Seventh-day Adventist completed a lifestyle questionnaire, including detailed dietary information. A subset of this population were selected for a sub-study on the health effects of smog, the AHSMOG study. This study enrolled 6,338 persons who have been followed with several questionnaires including the most recent 2000 questionnaire which contained questions on fractures, including hip fractures. A total of 2 684 persons were still alive and answered the question. Of these 974 were males and 1721 females. During 13 years of follow-up, hip fractures after the age of 35 were reported by 77 persons, 63 females (3.7%)and 14 males (1.4%). In addition, we obtained surrogate information from 400 (66%) of those who had died since our last follow-up in 1993. Of these, 90 (22.5%) had experienced hip fracture,74 females and 16 males. Since detailed information on diet, including vegetarian or non-vegetarian dietary preferences were obtained at baseline in 1976, we will report risk of hip fracture according to variations in dietary patterns, especially vegetarian status versus omnivores. If possible, data will also be presented for lacto-ovo vegetarians and vegans separately.

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Tuesday, April 9, 2002

Plenary Lecture

Our knowledge is far from complete regarding the relationship between vegetarian diets and human health. However, scientific advances in the last decades have considerably changed the role that vegetarian diets may play in human nutrition. Essential components of a vegetarian diet include a variety of vegetables, fruits, whole grain cereals, legumes and nuts. Numerous studies show important and quantifiable benefits of the different components of vegetarian diets, namely the reduction of risk for many chronic diseases and the increase in longevity. Such evidence is derived from the study of vegetarians as well as other populations. While meat intake has been related to increased risk for a variety of chronic diseases, an abundant consumption of vegetables, fruits, cereals, nuts, and legumes all have been independently related with a lower risk for several chronic degenerative diseases, such as ischemic heart disease, diabetes, obesity, and many cancers. Also, frequency of consumption of plant foods has been identified as a factor for increased longevity in industrialized nations. Hence, whole foods of plant origin seem to be beneficial on their own merit for chronic disease prevention. This is possibly more certain than the detrimental effects of meats. Vegetarian diets, as any other diet pattern, have potential health risks, namely marginal intake of essential nutrients. However, from the public health viewpoint the health benefits of a well-planned vegetarian diet far outweigh the potential risks.

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A body of evidence from epidemiologic studies indicates that a higher consumption of plant-based foods such as fruits, vegetables, and whole grains is associated with significantly lower risk of CHD and stroke. In addition, several large prospective studies have consistently shown that a higher consumption of nuts reduces risk of CHD. The protective effects of these foods are probably mediated through multiple beneficial nutrients in these foods, including antioxidant vitamins, minerals, phytochemicals, and unsaturated fatty acids. Based on the existing data, it can be concluded that consumption of plant-based foods has an important role in the prevention of cardiovascular disease. However, most of current dietary guidelines emphasize target intake of specific macronutrients. But many individuals find it difficult to make dietary changes based on such numerical criteria, some of which are not based on solid scientific evidence. Recommending an overall pattern of dietary intake focusing on appropriate food choices (e.g., eat more whole grain products, fruits, and vegetables) might be easy for the public to interpret or translate into diets.

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Conventional risk factors for cardiovascular disease can only explain less than half of the occurrence of cardiovascular events. Hemostatic, thrombotic and inflammatory factors have an impact on cardiovascular disease end points. Because diet is a readily modifiable risk factor for cardiovascular disease, many studies have investigated the effects of diet on hemostasis and thrombosis, although very few have compared the effects of vegetarian and non-vegetarian diets on these factors. Some have looked at specific plant foods such as garlic or nutrients that are more easily obtained from a vegetarian diet such as fiber and vitamin E with regard to their effect on hemostatic and thrombotic factors. Soluble fiber intake is associated with lower levels of fibrinogen and Factor VIIc. In the context of a high-complex carbohydrate low-fat diet, fiber also lowers PAI-1 levels. The type of fat in the diet appear to have an impact on several factors of coagulation, fibrinolysis, and inflammation. Lowering intake of saturated fat and replacing with unsaturated fatty acid is beneficial in improving hemostatic and inflammatory factors. This presentation will provide a review of studies on plant based diets and hemostasis and thrombosis, and also discuss the challenges in conducting the research and interpreting the data on hemostasis and thrombosis in healthy populations

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Some but not all studies suggest that homocysteine (hcy), a sulfhydryl-containing amino acid, is an independent risk factor for cardiovascular events. Regardless of homocysteine’s status as a risk factor, understanding the dietary factors that impact plasma levels of this amino acid is important for determining why elevated hcy levels have been associated with cardiovascular disease in both prospective and retrospective studies. Vegetarian diets provide some unique opportunities to look at nutritional factors that impact homocysteine economy. This presentation will examine how dietary

factors—with particular reference to plant-based eating styles—can impact a number of physiologic processes that have been demonstrated to have a role in homocysteine economy. Topics will include: precursors for homocysteine synthesis (specifically methionine); nutrients involved in homocysteine metabolism (such as pyridoxine, folic acid, vitamin B-12, betaine, and choline); substrates that affect methylation demand; as well as other factors that can impact homocysteine metabolism such as estrogenic compounds and dietary elements that may modulate the thyroid axis.

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Background: A report on the relationship between fluid intake and risk of fatal coronary heart disease (CHD) and stroke. Materials and Method: Using data from the Adventist Health study, a prospective cohort study of 34,198 men and women, we examined the associations between intake of water and fluids other than water and (a) fatal CHD among the 8,280 male and 12,017 female participants aged 38 to 100 years who were without heart disease, stroke or diabetes at baseline in 1976 and (b) fatal stroke among 1807 men and women who reported having CHD or stroke at baseline. A total of 246 fatal CHD events and 123 stroke deaths occurred during a six-year follow-up. Results: For fatal CHD, high daily intakes of water (five or more glasses) compared to low (one to two glasses) were associated with relative risk (RR) in men of 0.46 (95% confidence interval (CI): 0.28, 0.75), p trend 0.001, and in women, 0.59 (95% CI: 0.36, 0.97). High vs. low intake of fluids other than water was associated with a RR of 2.47 (95% CI: 1.04, 5.88) in women and 1.46 (95% CI: 0.7, 3.03) in men. All associations remained virtually unchanged in multivariate analysis adjusting for age, smoking, hypertension, body mass index, education, and (in women only) hormone replacement therapy. For fatal stroke, the age and sex adjusted RR for high and low intake of water respectively were 0.52 (95% CI: 0.32, 0.86), and 0.63 (95% CI: 0.38, 1.03), p trend 0.01. These associations also remained virtually unchanged in multivariate analysis adjusting for age, sex, blood pressure, smoking, body mass index, diabetes and exercise. The direct association between intake of fluids other than water and stroke death was not significant. Conclusion: These results suggest that fluid intake may deserve further consideration as a risk factor for fatal CHD and stroke.

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Background: To compare fasting total plasma homocysteine (tHcy) levels in vegans, lacto-ovovegetarians and control subjects, and to evaluate the relationships between total plasma homocysteine levels and nutritional variables in vegetarians. METHODS. The study was conducted on 45 vegetarian subject: 31 vegans (19 males,12 females; mean age 45.8 +- 15,8 years), 14 lacto-ovovegetarians (6 males, 8 females; mean age 48,5+- 14,5 years),and 29 control subject (19 males, 10 females; mean age 43,4+- 16,7). tHcy was evaluated by high performance liquid chromatography. Serum vitamin B12 and folate were performed by automated chemiluminescence systems. Clinical records, nutritional and anthropometric variables were collected for all vegetarians subjects. Results: Hcy was significantly higher in vegetarian subjects than in controls (23,9 +- 21,3 vs 11.6 +- 4,9 umol/l, p<0,001. The prevalence of hyperhomocysteinemia was higher in vegetarians than in controls (53,3% vs 10,3%, p<0,001). Serum vitamin B12 levels were lower in vegetarians than in control subjects (171.2+-73,6 vs 265+-52,2 p<0,01, normal range: 220-740 pmol/l. Significant inverse correlations were found in vegetarian subjects between tHcy and serum vitamin B12 levels (r=-0.776, p<0,001) and between tHcy and serum folate levels (r= 0.340, p<0.05). Positive correlations were found between tHcy and mean red-cell volume (r= 0,44, p<0.01) and between tHcy and fat-free mass (r=0.36, p<0.05. Conclusion: Vegetarian subjects presented significantly higher tHcy levels, higher prevalence of hyperhomocysteinemia, and lower serum vitamin B12 levels than controls.

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Background: Evaluation of cobalamin and homocysteine status in German vegans and research focusing upon status differences between strict (VGS, n=98) and moderate vegans (VGM, n=56; up to 5 % of energy intake derived from eggs, milk or other dairy products). Materials and Methods: Subjects for the cross-sectional study were recruited in 1993 through advertisements in German journals. Of 868 respondents 154 fulfilled the study criteria (vegan nutrition one year prior to study start, minimum age 18, no pregnancy or child-birth during the last 12 months) and participated in all study parts (questionnaire, 2 food-frequencies, blood assembly). Results: Median plasma cobalamin levels of strict vegans were lower (p=0.000) than of moderate persons (130 resp. 186 pmol/L) whereas men showed lower values (p=0.011) than women (127 resp. 175 pmol/L). A slight relation between duration of vegan regimen and cobalamin concentration was observed (Spearman r=-0.203, p=0.007). The study revealed higher (p=0.005) median plasma homocysteine levels in strict vegans than in moderate vegans (13.3 resp. 11.5 : mol/L). Also higher (p=0,000) levels were found in men than in women (15.4 resp. 10.6 : mol/L). Duration of vegan diet correlated positively with homocysteine (Spearman r=0.341, p=0.000). Cobalamin and homocysteine were inversely correlated (Spearman r=-0.671, p=0.000). Cobalamin deficiency (<110 pmol/L) is found in 37 % of VGS compared to 7 % of VGM. The frequency of hyperhomocysteinemia (>15 : mol/L) is higher in both groups (42 % resp. 24 %). Conclusion: Prevalence of inadequate cobalamin status in vegans is high. Although moderate vegans show more favorable cobalamin and homocysteine levels than strict vegans, both groups experience a decrease of cobalamin and an increase in homocysteine values as duration of vegan regimen increases. Vegans should take cobalamin supplements into consideration in order to minimize risk of cobalamin deficiency and cardiovascular disease.

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Dietary regimens that alter diet composition without a specific limit on energy intake, particularly low-fat, vegetarian diets similar to those for heart disease reversal programs, may promote effective weight control.

Methods: This study investigated the effects of a low-fat, vegan diet (VEG) on body weight, dietary intake, and RMR in 59 free-living, moderately overweight (BMI = 28- to 40 kg/m2), postmenopausal women, using as a control the National Cholesterol Education Step II diet (CON), in the absence of recommendations for increased exercise. Volunteers were randomly assigned to VEG or CON diets for 14 weeks and met once each week to receive nutrition and cooking information and group support. At baseline and at 14 weeks the following data were collected: three-day weighed food records, Bouchard Three-Day Physical Activity Records, resting metabolic rate (RMR) via indirect calorimetry, waist and hip circumference, body composition by air-displacement plethysmography, and body weight using a digital scale.

Results: Energy intake dropped in both groups, with reductions of 1.53 " 2.54 MJ (365 " 607 kcal, p < 0.01) in the VEG group and 1.49 " 1.53 MJ (355 " 365 kcal, p < 0.001) in the CON group. Mean body weight dropped by 5.8 kg, or 0.4 kg per week, in the VEG group, significantly more than the 3.8 kg mean weight change in the CON group. Reductions in BMI and waist circumference were also significantly greater in the VEG group, compared to the CON group. Mean reductions in hip circumference, body fat, and RMR were similar in the two groups.

Conclusion: The use of a low-fat, vegan diet was associated with a significantly greater weight loss in moderately overweight, postmenopausal women than a low-fat diet despite the absence of any prescribed limit on energy intake and the request not to alter exercise patterns.

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Background: The reasons for young people in Sweden to become vegans are ethical rather than health reasons. There was concern that the nutritional density in their diet was unfavorable compared with omnivorous diet because of omission of animal foods without addition of a broad variety of plant foods. The aim was to investigate the nutritional density of a vegan diet compared with an omnivorous diet consumed by adolescents. Subjects and Methods: Dietary intake of 30 vegans, 50% females, 17.5 ± 1.0 years compared with 30 sex-, age-, and height-matched omnivores was assessed using a diet history interview. Dietary intake was validated by the doubly labeled water method. Results : The diet history underestimated intake of energy by 13% and there was no difference between vegans and omnivores (P < 0.05). A higher density of carbohydrates, fiber, polyunsaturated fat, folate, vitamin C, vitamin E and magnesium was found in the vegan diet compared with the omnivorous diet (Table 1). A lower density of protein, saturated fat, cholesterol, riboflavin, niacin, vitamin B 12, vitamin D, calcium, phosphorus, zinc and selenium was found in the vegan diet compared with the omnivorous diet. Conclusion: A more favorable nutritional density as far as decreased risk of coronary heart disease is concerned, was found in the vegan diet compared with omnivorous diet . However, a vegan diet needs to be supplemented with vitamin B 12, and had a lower density of e.g. calcium and selenium compared with the omnivorous diet.

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Background: Vegetarianism has been claimed to confer a lessened risk for several diseases including coronary heart disease (CHD), blood hypertension, diabetes and cancer. However, the mechanisms involved in this cardiovascular protection are not well understood. Methods: In this observational study carried out in July to September 1997, we compared blood pressure (BP), blood lipids, body mass index (BMI), blood levels of glucose, urea, creatinine, uric acid, calcium, potassium, and hematocrit and urine among 3 dietary groups of adult Peruvians: Vegetarians (VEGs - no consumption of animal flesh); Semi-vegetarians (SVEGs - one to two servings of animal flesh per week; and Omnivorous (OMNs - daily consumption of animal flesh). In phase 1: we asked to complete a questionnaire and we measured BP and BMI from 105 VEGs, 34 SVEGs, and 45 OMNs. In phase 2: laboratory parameters were obtained from 38 VEGs, 15 SVEGs, and 31 OMNs. Group differences were tested by using analysis of variance (ANOVA) with group comparisons performed with Tukey & #8217;s post hoc test. Results: The main results were: (1) only 2.9% of the VEGs were confirmed to be hypertensive (by self-reporting) compared with 13.3% of the OMNs (p<0.05); (2) Prevalence of obesity was significantly greater in OMNs (33%) compared to SVEGs (0%) and VEGs (11%), p<0.05; (3) CT/HDL index average were lower among SVEGs and VEGs (4.4 " 1.2 and 4.7 " 1.5 respectively) compared with the OMNs (5.6 " 1.3) (p<0.05); (4) LDL/HDL index average were lower among SVEGs and VEGs (3.0 " 1.0 e 3.0 " 1.1 respectively) compared with the OMNs (3.7 " 1.1) (p<0.05); (5) the prevalence of hypercholesterolemia (>200 mg/dl) was lower in VEG group (31.6%) compared to SVEG and OMN groups (60.0 and 58.1% respectively), p<0.05; and (6) the prevalence of low-HDL (<35 mg/dl) was lower in VEG and SVEG groups (23.7 and 20.0% respectively) compared to OMN group (51.6%), p<0.05. Conclusions: We concluded that, among this group of Peruvians, the VEGs and SVEGs subjects are exposed to less degree of CHD risk factors when compared to the OMNs subjects.

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Linolenic acid (18:3n-3) is converted to long chain n-3 fatty acids, notably eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3,DHA) in animal tissues. Prospective cohort studies (Ascherio et al.1996; Hu et al. 1999) have examined the relationship between the intake of n-3 fatty acids and CHD risk and shown that the intake of both linolenic acid and long chain n-3 fatty acids is associated with decreased risk of fatal CHD independent of known risk factors. We report plasma concentrations of n-3 fatty acids in omnivore (n=262), vegetarian (n=257) and vegan (n=249) men recruited into the EPIC study. Results are shown as mean values with 95% confidence intervals. Plasma concentrations of all n-3 fatty acids were higher in the omnivores than in the vegetarians and vegans. The differences were most marked for EPA and DHA. The proportion of DHA in plasma lipids was 1.46 wt% in the omnivores, 1.02 wt% in the vegetarians and 0.62% in the vegans. The low DHA concentrations are in agreement with earlier studies (Sanders et al. 1978). The ratio of linoleic/linolenic acid in plasma of the omnivores, vegetarians and vegans was 20.5, 24.1 and 25.6 respectively. This would suggest that the low DHA concentrations were not a consequence of a high ratio of linoleic/linolenic acid in the diet. It seems likely that the variations in DHA concentrations are a consequence of preformed DHA in the diet. The intake of DHA in the omnivore subjects was estimated to be 50mg/d (95%CI 40,60). Whether these differences in plasma n-3 fatty acid concentrations are of pathophysiological significance remains to be determined.

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Background: Mahatma Gandhi, a staunch vegetarian observed in his book titled ‘Food Shortage and Agriculture’ while suggesting ways to ward off starvation, ‘Use should be made of herbs etc. which grow wild and which can be eaten with advantage. Research therein is necessary’. People today demand functional foods also known as nutraceuticals that have health promoting, disease preventing or medicinal properties. This has set the trend for bio-prospecting which prompted the authors to undertake this study. Materials and Methods: Five common wild plants with beneficial medicinal properties (Table 1), which can also serve as potential green leaf vegetables were selected for studying the nutritive aspects. These plants were Balloon-vine (Cardiospermum helicacabum), Indian penny wort (Centella asiatica), Jivanthi (Leptadenia reticulata), Climbing brinjal (Solanum trilobatum) and Pitabrngarajah (Wedelia chinensis). The leaves of these plants were hand picked, shade dried and powdered. Then vitamins such as carotene, thiamine, riboflavin, ascorbic acid and minerals such as calcium, iron and magnesium were estimated in leaves following standard procedures. The multifaceted medicinal properties of L.reticulata prompted a more detailed study. Apart from vitamins, protein, fat, fibre, carbohydrate, minerals and toxic elements in leaf and stem were estimated for L.reticulata.

Results : All the five plants tested had high content of carotene, thiamine, riboflavin, ascorbic acid, calcium, iron and magnesium when compared to commonly used green leaf vegetables (Table 2 & 3). The detailed study to find out the food value of L.reticulata revealed that the protein, fat, carbohydrate, vitamin A, thiamine, riboflavin, ascorbic acid, calcium, iron and magnesium were present in much higher quantity in L.reticulata than in most other green leaf and stem vegetables. The abundant presence of vitamins in L.reticulata substantiates the claim by Ayurveda (Indian System of Medicine) that this plant possesses tonic, stimulant and restorative properties. The toxic elements like cadmium, arsenic, mercury and lead were not present in detectable amount in the leaf and stem of L.reticulata (Table 4). Conclusions: If the nutrients present in the green leaf vegetables (GLV), in similar quantities are to be obtained from alternate animal sources, the cost will be comparatively much higher. These greens are inexpensive and it is advisable to include at least 50 g of GLV daily in one’s diet. The concept of nutraceutical is not new in India. All the five plants studied are being used as vegetables in India for specific beneficial medicinal properties. Some of the houses in rural India grow these plants in their gardens. These plants contain more vitamins in their leaves than many leafy vegetables known to us. Certain food items are discarded by some due to ignorance of their food values. The out come of the present study is so exhilarating that it pleads for the due and widespread recognition of these herbal food plants.

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Iron and zinc are the trace minerals of greatest concern when considering the nutritional value of vegetarian diets. With elimination of meat and increased intake of phytate-containing legumes and whole grains, both iron and zinc absorption are reduced from vegetarian, compared with non-vegetarian diets. The health consequences of reduced iron and zinc bioavailability are not clear, especially in industrialized countries with an abundant, varied food supply, where nutrition and health research has generally supported recommendations to reduce meat and increase legume and whole grain consumption. While vegetarians have lower iron stores, adverse health effects of lower iron and zinc absorption have not been demonstrated with varied, vegetarian diets in developed countries. Monitoring the iron status of vegetarian children and women of child-bearing age may be prudent; the benefit of routine iron supplementation has not been demonstrated. Improved assessment methods are required to determine if vegetarians are at risk of zinc deficiency. Supplementation recommendations should consider the likely nutritional interactions between these two nutrients and other trace elements such as copper. In contrast with iron and zinc, copper is derived principally from plant sources, and its bioavailability from a vegetarian diet appears unimpaired.

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The popularly held view that “clinical cobalamin deficiency due to dietary insufficiency is rare” may be true in meat eaters, but is not true for vegetarians. In this study of 128 vegetarians, 51% had serum vitamin B 12 concentrations below the minimum recommended by Herbert (220 pmol/L) (1). A comprehensive dietary questionnaire revealed that none were consuming sufficient servings of vitamin B 12 containing foods to obtain the recommended daily intake of the vitamin (2mg/day) and only 21% were achieving 1mg/day (Unlike in the United States, food supplementation with vitamin B 12 is very limited in most other countries). In patients with a vitamin B 12 deficiency, the dietician or clinician has several treatment options available, the efficacy of which is largely unknown. Sixty-seven vegetarians (consuming less than one serving of flesh foods per week) with low serum concentrations of vitamin B 12 (less than 220 pmol/L), volunteered for the study, and were divided into six age- and gender-matched groups, who were provided with one of five vitamin B 12 containing supplements. The groups were:

1. Controls – no supplements;
2. Vitamin B 12 fortified (1mg/250mL) soy milk alternative (500mL/day Sanitarium So Good, consumed as two separate 250 mL servings);
3. Vitamin B 12 fortified (0.6-1.0 mg/serving) meat analogues (one serving/day Sanitarium Gourmet range);
4. High dose tablets (50mg) – one per week;
5. Low dose tablet (2mg) – one per day;
6. Intramuscular (IM) injection (100mg) monthly.  

Subjects completed a detailed dietary and lifestyle questionnaire. A baseline biochemical profile,full blood count, vitamin B 12, folic acid and homocysteine concentration was performed. Vitamin B 12 and homocysteine concentrations were measured monthly for three months, and again two weeks after supplementation ceased. Significant increases in serum vitamin B 12 concentrations were observed in the IM injection group (+21%, p=0.0009); the So Good group (+31.7%, p<0.0001); the Low Dose tablet group (+18.7%, p=0.03); and the High Dose tablet group (+12.7%, p=0.002). No statistically significant changes were noted in the meat analogue group nor in the control group (p=0.24, p=0.18 respectively). Falls in serum homocysteine concentrations (indicating increases in body stores of vitamin B 12 were noted in all groups except the controls. A pre- and post-supplementation validated “wellbeing” questionnaire 2 confirmed that subjects who showed either increases in serum vitamin B 12 concentrations or falls in homocysteine concentrations “felt better” after three months supplementation (p<0.00006).

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Comparisons of diets and disease rates between Adventists and non-Adventists, and prospective cohort studies among Adventists have both contributed greatly to our general understanding of nutrition and health. The most fundamental conclusion regarding nutrition and health, to which the Adventist Health Studies have contributed greatly, has been that maintaining a lean body weight throughout life is central for optimal health. Other important contributions have included the value of nut consumption for prevention of coronary heart disease, and the roles of red meat and dairy products in the etiologies of cardiovascular disease and cancer. Although much progress has been made, many issues remain unresolved. In particular, rates of breast and prostate cancers remain high among Adventist populations despite an overall healthy lifestyle and long life expectancy, and there is even some suggestion that risks of breast cancer may increase with duration of being a vegetarian. One topic of great general interest, which may be uniquely studied among an Adventist population, is the effect of soy phytoestrogens in disease prevention. Although soy consumption has been hypothesized to contribute to the low rates of breast cancer in Asian populations, several intervention studies using high doses of soy estrogens have shown changes in breast tissue or nipple fluid that would predict higher rates of breast cancer. Also, high intakes of carbohydrate, which are often characteristic of vegetarian diets, are associated with hyperinsulinemia, which has been hypothesized to increase risks of some cancers. Resolution of these and other critical issues is needed to provide optimal guidance regarding healthy diets, and the newly funded Adventist Health study will surely contribute importantly in this effort.

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Proposed Topics for Discussion: The following list of topics would be based upon findings from the “old” AHS mortality study as well as from the “new” AHS incidence study and the Adventist Health and Smog (AHSMOG) study.

1. Use of exogenous hormones in females (including oral contraceptives and hormone replacement therapy) and risk of breast cancer.
2. Past and passive smoking and risk of selected cancers including urinary bladder cancer and leukemia.
3. Medical history, particularly allergic reactions, and risk of several cancers.
4. Ambient air pollution and risk of cancer, cardiovascular disease and non-malignant pulmonary disease (results from the AHSMOG study).
5. Menstrual and reproductive histories and risk of selected female cancers.

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We are currently very limited in nutritional epidemiology by errors in dietary assessment. These include errors in recall and the recording of complicated data. Seasonal shifts in food consumption may lead to errors in recall. There are errors in the identity of brand names of commercial products, and also differences by plant species, maturity and storage time in the nutrient content of vegetables and fruit. In addition to the error problem, there is the difficulty of confounding in the analysis phase of a highly multivariate situation. Regression calibration is an innovative statistical method for correcting the effects of some of the measurement errors on the estimated relative risks of disease comparing different food and nutrient intakes. With a “crude” dietary questionnaire and in addition two correlated instrumental variables for each nutrient/food, a latent variable model can be constructed. Assumptions are necessary, but these can be relatively weak. Then an unbiased estimate of the standardized effect of changing the true nutritional intake on disease risk, is possible. This is usually equivalent to the effect of changing through a known percentile of true intake.

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Wednesday, April 10, 2002

Plenary Lecture

Nutrition ecology is a holistic concept, that encompasses the complete food system with consideration on the effects of nutrition on health, environment, society and economy. Nutrition ecology includes all components of the food chain beginning with production, harvesting and storage of food over transport, processing, packing and trade to preparation and consumption of food and ending with the disposal of all waste materials. Nutrition ecology has many origins that go back to antiquity. Ever since man started systematic agriculture, the environment and consequently health, society and many other aspects of human life were affected. With the beginning of industrialized agriculture and mass animal production, various negative influences became apparent. The quality of our food is determined among others by the quality of the environment. Also, our food habits influence the environment. Research data and calculations of various aspects document that vegetarian diets are best suited to protect our environment, to reduce pollution and global climate changes. These advantages add to the benefits of vegetarian diets concerning health and well being. In order to further maximize the positive impact of vegetarian diets on various other human endeavors, food should be produced regionally, should be consumed in the proper season and should originate from organic farming. Vegetarian diets embedded in these conditions are scientifically based, socially acceptable, economically feasible, culturally desired, practicable and have a high degree of sustainability.

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Animal product-based diets are more energy, land and water resource-intensive than plant-based diets. In general, animal-product based diets require about 35,000 kcal per day per person, whereas a lacto-ovo vegetarian diet requires about 25,000 kcal per day per person and a vegetarian diet about 20,000 kcal per day per person. [Note, 1 gallon of gasoline contains about 30,000 kcal.] Approximately 10 billion livestock animals are harvested for the animal-product diet system in the U.S. each year. The U.S. livestock population out-weighs the U.S. human population by about 5 times. Approximately 250 million metric tons of grain are fed to U.S. Livestock each year. This is sufficient grain to feed approximately 800 million people as vegetarians.

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Food production and consumption have a large environmental impact and diet choices may help in the limitation thereof. A comparative environmental analysis of meat production and the production of a processed protein food based on soybeans shows the following. Land requirements for meat production tend to be roughly a factor 6-17 larger than for soybean based protein production and water inputs 4.4-26 times larger. The efficiency of using fossil fuels in agriculture can be a factor 2.5-50 better for vegetable proteins, if compared with animal husbandry. Emissions associated with producing protein as meat may be 6 times higher for pesticides /biocides, more than a factor 100 larger for copper and at least 7 times larger for acidifying substances than the emissions associated with the equivalent production of processed protein food based on soybeans. Relatively low environmental impacts are also found for other vegetarian products. For instance lupine based cheese may require less than 20% of the land necessary for the production of an equivalent amount of cow milk in intensive animal husbandry and can be a factor 9-21 better as to the combined emission of acidifying, eutrophying and ecotoxic substances. In the European context per gram of protein, the input of fossil fuels for catching fish may be up to roughly 14 times larger than for the production of vegetable protein.

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Pesticide use in the US has increased as much as 33 times since the 1940s. In spite of this dramatic increase in the use of agricultural chemicals, an estimated 37% of all crop production is lost annually to pests. Concerns over the environmental consequences of pesticide use include; residues on food, ground and surface water contamination, persistence in the environment, damage to non-targeted species, and increased resistance in pests. In this paper we present a method to compare the environmental impact associated with the application of pesticides (EIAP) used to produce commodities for a vegetarian and non-vegetarian diet. We used the Adventist Health Study to identify dietary preferences of a group of Seventh Day Adventist in the state of California. A statistical comparison showed significant differences in the food consumption patterns of vegetarians and non-vegetarians. Our investigation was limited to agricultural practices in the state of California which is the largest producer of agricultural and food products in the US. The EIAP associated with the production of commodities uniquely associated with each diet was assessed using the environmental impact quotient of pesticides (EIQ) and statistics compiled by the California Department of Pesticide Regulation and USDA National Agricultural Statistics Service. An environmental hazard quotient was calculated for the production of each food item. A summary index, the dietary hazard index, was calculated and used to directly compare the EIAP for each diet.

The results of our study indicate that the production of a vegetarian diet in the state of California may be associated with a slightly greater environmental impact as calculated by the dietary hazard index. This could be due in part to the dietary preferences of our sample population, our selection of agricultural commodities, regional agricultural practices, or the differential application of pesticides to commodities consumed by vegetarians

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Background: The ecological impact differs between food items, but is generally less for foods of plant than of animal origin. This raises the question as to what ecological impact results from diets containing different proportions of animal food. Material and Methods: Based on cross-sectional data, the ecological impact of three different diet regimens is evaluated using the indicators primary energy, CO 2- and SO 2-equivalents. The diet groups consisted of healthy women aged 25 to 65 years: (1) an average Western diet and plant-centered dietary regimens following the preventive recommendations, (2) an ovo-lacto-vegetarian, and (3) a low-meat version diet. The calculations are based on the German nutrition sy stem with the sub-systems agricultural production and industrial processing. Results: The average Western diet results in a higher ecological impact than the plant-centered diets, especially the ovo-lacto vegetarian diet. The ecological impact for agricultural production is higher than for industrial processing, as both aspects heavily depend on the proportion of animal food that is included in the diet. Compared to a woman on an average Western diet, the use of primary energy of a low-meat eater is 41 %, and of an ovo-lacto vegetarian, 54 % lower; the emission of CO 2-equivalents is 37 and 52 % lower, respectively, and that of SO 2-equivalents is 50 and 66 % lower, respectively. The ratio of the primary energy use to the average intake of energy demonstrates that the ovo-lacto vegetarian diet is the most energy-efficient diet regimen.

Conclusions: Changing from a diet with an average proportion of animal food to a low-meat diet, or to an ovo-lacto vegetarian diet results in a reduction of the ecological impact by one to two-thirds, depending on the extent to which the changes are made, and on the indicator studied. The ecological savings can be increased by purchasing regionally and organically grown foods.

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Alpha-linolenic acid (C18:3) is a building block for the longer chain omega-3 fatty acids, EPA and DHA. Consequently, they would be expected to elicit similar biological effects. However, less than 10% of C18:3 is converted to what is thought to be the biologically active metabolites, EPA and DHA. Epidemiologic and clinical trials have shown that these omega-3 fatty acids have marked beneficial effects on coronary heart disease morbidity and mortality. The epidemiologic studies have shown that fish consumption can reduce coronary artery disease, especially in individuals at high risk (Marckmann & Gronaek, 1999). Likewise, there is epidemiologic evidence that dietary alpha-linolenic acid (ALA), an omega-3 fatty acid from plant sources, elicits cardioprotective effects (Hu, et al, 1999). Several randomized controlled clinical trials (Burr, et al, 1989; Singh, et al, 1997; GISSI-Prevenzione Investigators, 1999) have shown that fish oil supplements markedly decreased coronary morbidity and mortality in secondary prevention trials. In addition, the Lyon Diet Heart Study and The Indian Experiment of Infarct Survival Study, both controlled clinical trials, have shown that diets high in ALA significantly decreased secondary events (de Lorgeril, et al, 1999; Singh, et al, 1997). With respect to effects on plasma lipids and lipoproteins, numerous studies have shown that EPA and DHA decrease plasma triglyceride levels in a dose-dependent manner (Harris, 1997). The greatest triglyceride-lowering response is observed in individuals with hypertriglyceridemia. There is some evidence that suggests ALA in high doses also reduces triglyceride levels, although the response is less than observed for EPA and DHA. Alpha-linolenic acid and linoleic acid have similar lipid and lipoprotein effects ehn fed at levels typically found in the diet. Lower blood pressure and improved vascular function may be additional benefits of dietary omega-3 fatty acids (Mori & Beilin, 2001). With respect to blood pressure, one study showed a marked decrease in systolic blood pressure of ~4% with supplementation of EPA plus DHA (3.4 g/d), but not with ALA (9.2 g/d) (Kestin, et al 1990). Six recent studies (Chin, et al, 1993; Fleischhauer, et al, 1993; McVeigh, et al, 1993; Goode, et al, 1997; Goodfellow, et al, 2000; Mori, et al, 2000) have shown significant improvements in vascular dilation responses when DHA and EPA supplements (3-10 g/d) are consumed for > 3 weeks. One study (Mori, et al, 2001) suggests that these effects on vascular reactivity are entirely due to DHA; no significant change in vasodilatory response was seen when EPA was administered alone. Current studies are ongoing to examine potential mechanisms for the demonstrated cardiac health benefits of omega-3 fatty acids from both fish and plant sources. Platelets play an important role in hemostasis and thrombosis. Studies have shown that high-linoleic-acid diets increase platelet activation and aggregation to various agonists, whereas high intakes of ALA and EPA/DHA can replace n-6 fatty acid, i.e., arachidonic acid, in the membrane, resulting in decreased amounts of proaggregatory thromboxane A2 and increased amounts of antiaggregatory thromboxane A3, therefore, decreasing platelet aggregation (Saker, et al, 1998). Consumption of ALA from vegetable oil and EPA/DHA froma marine source shows comparable effects on platelet aggregation and hemostatic factors in humans (Freese & Mutanen, 1997). However, results from animal studies demonstrated DHA is more effective (Wensing et al, 1999; Yamada, et al, 1998). Comparing effects on immunity in healthy humans, one study showed that daily dietary supplementation with one-gram fish oil (720 mg EPA plus 280 mg DHA) or 770 mg gamma linolenic acid (GLA), but not other n-6 or n-3 PUFA (ALA, arachidonic acid and DHA) can decrease T lymphocyte proliferation up to 65% (Thies, et al, 2001); while another study showed that one gram of EPA plus DHA (720 mg EPA plus 280 mg DHA) but not other n-3 or n-6 PUFA (ALA, GLA, AA and DHA) can decrease natural killer cell activity by 48% after 12 weeks of supplementation (Thies, et al, 2001). In summary, omega-3 fatty acids have diverse biological effects. Clinically, they have potent cardioprotective effects which have been demonstrated for ALA as well as EPA and DHA. Because of these beneficial effects, it is prudent to develop population-based strategies to increase omega-3 fatty acid intake.

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This session will provide a brief overview of current essential fatty acid intake sin vegetarian/vegan populations, as they compare to recommended intakes. Research assessing fatty acid status in vegetarians and vegans will also be reviewed. The primary challenges vegetarians face in achieving optimal essential fatty acid status, and the practical dietary changes necessary to achieve the desired outcome will also be discussed. At present, vegetarians and vegans are at an advantage where intakes of total fat, saturated fat and cholesterol are concerned, but at a potential disadvantage in their intakes of the physiologically active forms of omega-3s (EPA and DHA) are often negligible. Alpha-linolenic acid, the plant form of omega-3, is converted by the body to the active longer-chain omega-3 fatty acids at a rate of only 5-10% for EPA and 2-5% for DHA. Thus, the total omega-3 requirements may be higher for vegetarians than for non-vegetarians. To maximize omega-3 fatty acid status in vegetarians, the following dietary guidelines are recommended:

1. Limit intake of saturated fats and trans fatty acids.
2. Avoid excessive intakes of omega-6 fatty acids, particularly from omega-6 rich oils.
3. Opt for foods and oils rich in monounsaturated fatty acids as the primary sources of fat.
4. Ensure adequate daily intakes of foods rich in omega-3 fatty acids.
5. Consider including a direct source of long-chain omega-3 fatty acids in the diet, particularly during pregnancy and lactation.

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Background: Epidemiological data generally support the association between high fruit and vegetable intake and reduced risk of cancers of the digestive tract. Materials and Methods: We summarized the published epidemiological evidence from case-control and cohort studies of cancers of the aerodigestive system (mouth, pharynx larynx, lung, esophagus, stomach and colorectum), breast and bladder, using meta-analytical techniques. Dose-response relationships were estimated using linear-logistic random effect models with consumption of vegetables and fruits in separate models for each cancer site. Results: The pooled estimates of the association between vegetables and cancer obtained from cohort studies are suggestive of a protective effect for all the cancer sites investigated: breast, lung, bladder, stomach, colorectum, but the association was statistically significant only for gastric cancer (RR per 100 g/day increase = 0.88; 95% CI: 0.79-0.98). The average estimate for breast cancer suggests no association (RR per 100 g/day increase = 0.99; 95% CI: 0.96-1.01). Case-control studies provide statistically significant pooled odds ratios for cancer of the breast, lung, stomach and colorectum. For cancers of the bladder, mouth and pharynx, larynx and esophagus, case-control studies suggest a protective effect, but the pooled estimates are not statistically significant. Both cohort and case-control studies are more supportive of the protective effect of fruit than of vegetables for the cancers included in the meta-analysis. The pooled RR from cohort studies is statistically significant for cancers of the lung (RR per 100 g/day increase = 0.86; 95% CI: 0.78-0.95) and, for cancer of the lung, bladder, colorectum, mouth and pharynx, larynx and esophagus, the protective effect in case-control studies was significant only for breast cancer (RR per 100 g/day = 0.92; 95% CI: 0.84-1.01). Conclusions: These results indicate that high intakes of fruits and vegetables are associated with a significant decrease in risk of developing cancer of the stomach and esophagus, while the postulated protective effect on colorectal cancer appears to be less clearly supported by the results of large prospective cohort studies published during recent years.

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Numerous studies have demonstrated in vitro effects of components from fruits and vegetables on various measure of oxidative cellular damage. However, the questions that have not been answered satisfactorily deal with the absorption/metabolism of antioxidant components in fruits and vegetables and whether they are absorbed in sufficient quantities and in a form in which effects could be observed on in vivo measures of oxidative cellular damage. The focus of this review will be on clinical studies that provide information about possible in vivo changes in antioxidant status with fruit and vegetable consumption. Unfortunately, in human clinical studies, a lot of the measures of antioxidant status are based upon plasma or urine measures which may not give a true assessment of the antioxidant status at the cellular level. However, those indicators of alterations in cellular oxidative stress to be considered include:(1) Susceptibility of LDL to ex vivo oxidation; (2) Platelet function; (3) Urinary excretion of 8-0HdG; (4) Lipid oxidative damage (malondialdehyde and F(2)-isoprostane); (5) Protein carbonyls; and (6) Changes in blood antioxidant capacity. A potential role for food flavonoids and polyphenolics as antioxidant will be discussed.

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Thousands of chemical structures have been identified in plant foods. Many are found in spices. Typically, spices are the dried aromatic parts of plants – generally the seeds, berries, roots, pods, and sometimes leaves – which mainly, but not invariably, grow in hot countries. Given the wide range of botanical species and plant parts from which spices are derived, they can contribute significant variety and complexity to the human diet. In the past, the medicinal uses of spices and herbs were often indistinguishable from their culinary uses and for good reason; people have recognized for centuries both the inherent value, as well as potential toxicity, of phytochemicals in relation to human health. Plants have the capacity to synthesize a diverse array of chemicals. Understanding how phytochemicals function in plants may further our understanding of the mechanisms by which they benefit humans. In plants, these compounds function to: attract beneficial and repel harmful organisms; serve as photoprotectants; and respond to environmental changes. In humans, they can have complementary and overlapping actions, including antioxidant effects, modulation of detoxification enzymes, stimulation of the immune system, reduction of platelet aggregation, modulation of steroid metabolism, and antibacterial and antiviral effects. Embracing a cuisine rich in spice, as well as fruits and vegetables, may further enhance the chemopreventive capacity of diet.

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Insulin-like growth factor-I (IGF-I) is a peptide hormone that stimulates cell growth in many tissue types and thus may play a role in the development of cancer. There is growing evidence from prospective studies that IGF-I is involved in the aetiology of several cancers, including the prostate, breast, colo-rectum and lung. Circulating levels of IGF-I and its main binding proteins are sensitive to nutrition and could be one mechanism through which diet may influence cancer risk. However, little is known about the dietary determinants of IGF-I levels in the general population. Methods: To identify the nutritional determinants of circulating concentrations of IGF-I and its main binding proteins, cross-sectional data were taken from 696 and 294 men and women involved in the Oxford arm of the European Prospective Investigation into Cancer and Nutrition. The study population included equal numbers of meat-eaters, lacto-ovo-vegetarians and vegans to obtain a wide range of nutrient intake. Serum concentrations of IGF-I were measured in men and serum concentrations of IGF-I and its main binding proteins (IGFBP1, 2 and 3) were measured in women using immunoenzymatic assays. Results: Serum IGF-I concentration was significantly 9-13% lower among vegan men and women compared with meat-eaters and vegetarians after adjustment for age and body mass index. Serum IGFBP-1 was significantly 45% higher among vegan women compared with meat-eaters and vegetarians. Serum IGFBP-2 was also significantly 37% higher among vegan women compared with meat-eaters, whilst vegetarian women had intermediate values. Serum concentrations of IGFBP-3 were similar between the three dietary groups. Conclusion: A vegan diet is associated with a lower circulating IGF-I concentration and a higher IGFBP-1 and IGFBP-2 concentration compared with an omnivorous or vegetarian diet. Nutritional factors specific to a plant-based diet may reduce bioavailable IGF-I levels to an extent that is of clinical significance.

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Prion diseases, or transmissible spongiform encephalopathies, include Creutzfeldt-Jakob disease (CJD) in humans, and scrapie and bovine spongiform encephalopathy (BSE) in animals. These neurodegenerative diseases are invariably fatal and can be transmitted by inoculation or by dietary exposure. They are associated with the accumulation of an altered, disease-associated form of the normal prion protein. Pathologically, prion diseases result in neuronal cell death and a characteristic 'spongiform' appearance of the brain tissue. The emergence of a variant form of CJD (vCJD) in the UK in 1996 has been causally and experimentally linked to the BSE epidemic in the UK in the 1980s and early 1990s. The finding that BSE is transmissible to different animal species, unlike previously characterised prion diseases such as sheep scrapie, has raised enormous public health concerns worldwide. Although it is not yet possible to gauge the size of a potential vCJD epidemic, there has been significant dietary exposure to BSE-infected material in Britain, and wider implications of the transmissible nature of BSE and vCJD include spread of disease via surgical instruments. The threat to public health has intensified research efforts to understand the molecular basis of prion diseases and their transmission between species, to improve methods of diagnosis and to develop therapeutic strategies for treatment and prevention of prion diseases.

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Abstract unavailable.

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Antibiotic resistance constitutes a global public health crisis. Overuse and inappropriate use of antibiotics hastens the development of resistance. Currently, there is no concerted effort to monitor actual antibiotic use in the U.S. Recent estimates, however, find that 70% of all antibiotics produced in the U.S. each year are given to healthy food animals, and more than half of these drugs are identical or closely related to antibiotics used in treating human illness. Antibiotic resistant pathogens can result from the use of antibiotics in food animals, and these are transmitted to humans. Typically, transmission occurs through the food supply. However, resistant bacteria also can be transmitted directly through farm contact with animals or their manure, and potentially through contaminated surface water, groundwater, or air surrounding the livestock facility as well. Emerging evidence for the latter, non-food pathways suggests that antibiotic overuse in agriculture might better be considered an ecological health problem rather than simply a question of food safety.

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Thursday, April 11, 2002

Abstract unavailable.

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Although still speculative, accumulating evidence suggests that soy food consumption may reduce risk of several chronic diseases including coronary heart disease, osteoporosis, and certain forms of cancer. The potential health benefits of both soy protein and soybean isoflavones are under investigation. Consequently, consumers and health professionals are seeking guidelines for appropriate soy intake, levels that are thought to be both efficacious and safe. The U.S. FDA recently approved a health claim for the cholesterol-lowering effects of soy protein and set 25 g of soy protein as the target intake for cholesterol reduction. However, the FDA did not offer an opinion on an appropriate level of isoflavones and the suggested protein intake applies only to cholesterol reduction, not to other risk factors for coronary heart disease or other chronic diseases. There are at least four different types of data upon which intake recommendations can be based. These are (1) Asian soy intake, (2) epidemiologic findings, (3) intervention studies and (4) the relationship between soy intake and serum isoflavone levels. Each of these offers advantages and disadvantages. Collectively, the evidence suggests that for the generally healthy adult population, the intake of approximately 15 g (range, 10 to 25 g) of soy protein and 50 mg (range, 30 to 100 mg) of isoflavones per day is safe and has the potential to exert health benefits. Incorporating this amount of soy into the U.S. diet is an achievable goal and is consistent with advice to consume a varied diet.

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Lifestyles that include exercise and a diet low in red meat and fat, but high in fish, rice and soy is associated with health benefits. Soy food consumption is very low in the U.S., except for one segment of the population, infants fed soy-based formula. Soy formula is made with soy protein isolate containing isoflavones (SPI +). These isoflavones can function as estrogen agonists, antagonists, or selective estrogen receptor modulators, depending on the conditions. Much research has focussed on health effects (both beneficial and adverse) of soyfoods on health, but no two areas have been more controversial than those related to infant formula and cancer. We have studied the effects of soy protein isolate and isolfavones on various aspects of health throughout the lifecycle. Our results suggest that: (1) consumption of soyfoods have health benefits that outweigh any health risk; (2) soy protein and purified isolfavones may have unique biological actions leading to different health effects; and (3) there are potential health concerns in at least two areas related to soy products, including drug efficacy and the actions of purified isoflavones. Further research is needed to confirm the results and to investigate the more subtle effects that could occur during development or that could surface later in life.

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The recent recommendations of the American Diabetes Association on medical nutrition therapy of patients with type 2 diabetes state that carbohydrate and monounsaturated fatty acids (MUFA) should together provide 60-70% of energy intake, and that metabolic profiles, need for weight loss, and individual choices should be considered when determining the MUFA content of the diet. High-carbohydrate diets may worsen postprandial glycemia and induce hypertriglyceridemia, although large amounts of dietary fiber ( » 50 g per day) offset these putative atherogenic changes. In recent years, high-MUFA diets based on MUFA-rich oils and fats or whole foods have been compared with high-carbohydrate diets for effects on a number of cardiovascular risk outcomes in diabetic patients. Early studies using metabolic diets and with wide between-diet differences in total fat content (15-25% of energy) generally found a beneficial effect of MUFA diets on triglycerides and glycemic control. More recent studies with prescribed diets and a more physiological difference in total fat between low-fat and high-MUFA diets of <15% of energy have found similar effects on lipid and glycemic profiles. Gene-diet interactions are likely to play a role in the heterogeneity of responses observed. Few studies have examined the effects of low-fat diets versus high-MUFA diets on the postprandial hyperlipidemia of diabetic patients, with conflicting results: postprandial triglycerides are either unchanged or decreased by MUFA diets, but atherogenic chylomicron remnants increase postprandially compared to low-fat diets. However, when compared to high-carbohydrate diets in diabetic patients, high-MUFA diets generally decrease the susceptibility of LDL particles to oxidation. Limited evidence suggests that MUFAs also favourably influence blood pressure, coagulation, and endothelial function. Energy-controlled high-MUFA diets do not promote weight gain and could be more acceptable than low-energy, low-fat diets for weight loss in overweight subjects. Taken collectively, these evidences suggest that a diet with MUFA providing up to 25% of energy is a good alternative diet to a low-fat diet for medical nutrition therapy of patients with type 2 diabetes.

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The roles of obesity and central distribution of body fat, as well as hyperinsulinemia have been studied in the San Luis Valley Diabetes Study. Hyperinsulinemia, obesity and central fat distribution accounted for some of the less favorable CVD risk factors associated with impaired glucose tolerance. Visceral fat distribution assessed by CT scan and WHR in pre-menopausal women, accounted for a significantly greater degree of variance in CVD risk than total body fat mass. Cumulative insulin response was the primary metabolic variable associating body fat distribution to CVD.

The use of a low-fat vegetarian diet in patients with NIDDM has been associated with significant reductions in FBS and body weight. A predominantly vegetarian diet may have important beneficial effects on diabetic nephropathy. Regression of diabetic neuropathy with a vegan diet has been reported. These studies were all accompanied by weight loss.

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Plant-centered eating was the focus of the earliest nutrition therapy for diabetes- wheat grains, fresh grits, grapes, honeyberries and sweet beer (Papyrus Ebers, 1550 BC). Over the years, a variety of nutrition theories have been recommended, discarded and re-emerged. Today, many individuals with diabetes have become more interested in plant-centered eating as a health promoting measure to reduce the risk of diabetes complications such as cardiovascular disease. Carbohydrate-containing foods are a significant part of the meal plan in all types of vegetarian diets. Because 80-90% of digestible carbohydrate enters the bloodstream as glucose in the first few hours after a meal, it is important to focus on the total amount of carbohydrate in the vegetarian meal plan and its effect on an individual’s glycemic control. This presentation will review the benefits and challenges of plant-centered nutrition for individuals with Type 1 and Type 2 diabetes, as well as discuss practical methods for incorporating plant-centered nutrition into the currently used diabetes meal planning approaches such as carbohydrate counting and the exchange system. Practical tips and useful resources will be provided to help individuals with diabetes make the transition to a vegetarian diet. Individuals with diabetes can successfully combine plant-centered eating and a diabetes meal plan with the encouragement, support and assistance of a registered dietitian.

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Frequent nut consumption is associated with lower rates of heart disease in several epidemiological studies. Also, nut-rich diets improve the serum lipid profile of participant in clinical trials. However, nuts are fatty foods and in theory their regular consumption may lead to body weight gain. Since obesity is a major public health problem and a risk factor for heart disease, clinicians and policy makers ponder the questions: Will hypercholesterolemic patients advised to consume nuts gain weight? Is recommending increased nut consumption to the general population for heart disease prevention a sound public health advise?

Epidemiological studies indicate an inverse association between frequency of nut consumption and body mass index. These studies also showed the protective effects of nuts against heart diseases in both thin and obese persons. A number of nut trials on free-living subjects, where no constraints on body weight were imposed, showed a non-significant tendency to lower weight while in the nut diets. Furthermore, a recent study of overweight adults, greater and more sustained weight loss was observed in the nut diet than the standard low-fat diet. In another line of evidence, preliminary data indicated that subjects on nut-rich diets excrete more fat in stools. Further research is needed to specifically study the effects of nut consumption on body weight. On the mean time, the cumulative data available do not indicate that free-living people on self-selected diets including frequent nut consumption have a higher body mass index or a tendency to weight gain.

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Any interpretation of a cultural dietary pattern must acknowledge its social, cultural, historical, political and economic contributing factors. Due to the complex and interrelated forces on a dietary pattern within a region, variability in dietary composition exists among and within all cultures. Since many diets within a culture are possible, varying by place, time and socioeconomic status, the tendency to choose a nutritionally balanced vegetarian diet for modelling purposes exists. Thus, the comparison of vegetarian diets across cultures must attempt to create food patterns utilizing Natives and cookbooks from each cultural tradition to ensure an accurate representation of each dietary pattern. Identification of the prominent foods within the Vegetarian Food Guide for a Western, Western fast food, Hispanic, Mediterranean-Italian, Mediterranean Middle Eastern, Asian and Continental Indian dietary pattern will enable the participant to recognize the potential for consuming a marginal intake or excess of specific nutrients across cultures. Nutrition educators must become knowledgeable of the special population groups at risk for consuming a marginal intake or developing nutritional deficiencies of specific nutrients across the cultural variations of the vegetarian and vegan diet.

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Plant-based diets are often rich in salads, pasta and vegetable dishes, dips, soups and stews that are commonly seasoned with various herbs. The present popularity of Italian, Mexican, Indian, Oriental and other ethnic dishes has resulted in an increased use of herbal seasonings, such as oregano, sweet basil, chili, rosemary, thyme, ginger, garlic and onions. The culinary herbal seasonings used to enhance the flavour of various dishes originate mainly from nine families of herbs: Umbelliferae, Labiatae, Piperaceae, Liliaceae, Solanaceae, Zingiberaceae, Lauraceae, Myrtaceae, and Cruciferae. The unique flavors associated with different herbs are provided by the aromatic ingredients of their essential oils and oleoresins (mixtures of terpenes such as thymol, menthol, limonene, carvone, cineole, etc) while their pungency is due to the alkaloids such as piperine in black pepper and capsaicin in red pepper. In addition, some herbs such as saffron, paprika, and turmeric are used to add color to food. Many of the phytochemicals in herbs that provide color and flavor to food are antioxidants and alter cellular metabolism in such a way to influence our health. Herbs from the Umbelliferae, Liliaceae, and Labiatae families and green tea possess phytochemicals that protect against cardiovascular diseases and cancer. Spices from the Lauraceae and Myrtaceae families are noteworthy for their effectiveness in improving glucose and insulin metabolism. A number of the culinary herbs and herbal beverages contain physiologically active compounds that make them useful in treating certain disorders. Cranberry juice is useful for urinary tract infections; ginger is effective as an anti-emetic for motion sickness; fennel and various mints have been used to treat coughs and colds; garlic is a useful wide spectrum antibiotic; raspberry tea is used for menstrual cramps and to aid in childbirth; and licorice root is useful for the treatment of ulcers.

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Purpose: While residential lifestyle intervention programs have successfully demonstrated coronary risk reduction through education, this pilot study was designed to assess the feasibility of developing a more cost-effective template for effecting lifestyle changes and clinical outcomes through a community-based lifestyle intervention program. Materials and Methods: A 40-hour educational curriculum, delivered over a 30-day period with clinical assessment before and after, was offered through the Swedish American Health System to the general public in Rockford, IL. The participants were encouraged and instructed to exercise and to embrace a more optimal diet of largely unrefined plant-foods high in complex carbohydrates and fiber and low in fat. Results: Of a total of 250 enrolled, 242 (78 men, 164 women) graduated. With a mean age of 54 +/-12 years, the high risk cohort exhibited clinically established coronary artery disease (12%), diabetes (16%), hypertension (55%), hypercholesterolemia (79% had LDL-C levels >100) and overweight (88%). At 4 weeks, participants had effected significant reductions in coronary risk factors, such as elevated high blood pressure, blood glucose, serum-lipids. Those at the highest risk showed the greatest improvement. Men with TC >220mg% showed a reduction of 21%. Similarly results were seen with LDL-C (men with LDL-C >160mg% went from an initial mean of 179 to 125 mg%) and TG (men and women with levels between 200 and 299mg% had mean reductions of 29% and 18%, respectively). Stepwise regression analysis showed that baseline lipid levels were the strongest predictor for change (p<0.001), followed by weight loss (p<0.01) and exercise improvement (p=0.06). Conclusions: Community-based intervention strategies can be successfully and cost-effectively utilized to lower coronary risk factor levels in a self-selected population. The true test, however, will be to what extent social infrastructures can be modified and alumni activities sustained in an effort to facilitate long-term adherence and sustained benefits.

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