Oral Presentations - abstracts

Monday, March 24, 1997

Keynote address

Populations of vegetarians living in affluent countries appear to enjoy unusually good health, characterized by low rates of cancer, cardiovascular disease, and total mortality. This important observation has provided fuel for many lines of research and has raised at least three general questions. Are these unusual health statistics due to better nondietary lifestyle factors, such as low prevalence of smoking and higher levels of physical activity? Are these statistics due to low intake of harmful dietary factors, in particular meat? Are these observations due to higher intake of beneficial dietary factors that tend to replace meat in the diets?

Due to the complex intercorrelations of dietary factors and other lifestyle variables, these questions have posed challenges to epidemiologists. However, there is now sufficient evidence to indicate that the answers to all three questions are likely to be "yes". Certainly, low smoking rates contribute importantly to the low rates of coronary heart disease and many cancers, probably including colon cancer, in the Seventh-day Adventist and other vegetarian populations. Also, avoidance of red meat is likely to account in part for low rates of coronary heart disease and colon cancer, but this does not appear to be the primary reason for general good health in these populations. Very generally, evidence accumulated in the past decade has emphasized the importance of adequate consumption of beneficial dietary factors, rather than just the avoidance of harmful factors. This includes abundant intake of fruits and vegetables, the regular consumption of vegetable oils including those in nuts, and the importance of consuming grains in a minimally refined state. The notion that fat per se is a major cause of ill health has not been supported by recent data. Many critical questions will require additional research. Further knowledge about the types of fruits and vegetables that are beneficial and their biologically important constituents would make possible more specific advice and more focused interventions. Also, observations that intakes of fish and poultry seem to be beneficial for some health outcomes raises the possibility that some of these foods also may contain components that are not consumed in optimal amounts in some diets. Although current knowledge already provides general guidance toward healthy diets, the accumulated evidence strongly indicates a powerful, yet complex, impact of diet on health and the need for further investigation.

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The contribution of legumes to overall dietary intake varies greatly among populations as legume intake differs markedly throughout the world. Not surprisingly, those countries that consume more plant-based diets also consume relatively more legumes. In fact, other than the obvious distinction of not including flesh products, the greater consumption of legumes by western vegetarians in comparison to omnivores may be the most distinguishing feature of vegetarian diets. Legumes are an excellent source of dietary fiber and on a caloric basis, are generally no more than 10% fat (the main exceptions being soybeans and peanuts) and between 20% and 30% protein. The glycemic index of beans is extremely low which suggests legumes may be a particulary important food for diabetics and for individuals who are at risk of becoming insulin resistant. Also, the bacterial metabolism of the indigestible oligosaccharides in legumes may produce beneficial health effects. Finally, legumes offer a variety of potentially beneficial phytochemicals such as saponins (found in a variety of legumes) and isoflavones (primarily found in soybeans). Recent data suggest isoflavones may promote bone health, and reduce risk of both cardiovascular disease and some forms of cancer.

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There is growing evidence that cereals and legumes play important roles in the prevention of chronic diseases. Early epidemiologic studies of these associations focused on dietary fiber rather than intake of grains or legumes. Generally, such studies indicate an inverse association of dietary fiber and risk of coronary disease; this observation has been replicated in recent cohort studies. Studies focused on grain or cereal intake are fewer in number; they tend to support an inverse association of whole grains with coronary heart disease. The association of dietary fiber with colon and other cancers have generally shown inverse associations; whether these are attributable to cereal or to other fiber sources or other factors is less clear. Although legumes have been demonstrated to lower blood cholesterol levels, epidemiologic studies are few and inconclusive regarding the association of legumes with risk of coronary heart disease. Legumes, in particular soy, have been hypothesized to decrease risk of some cancers, but epidemiologic studies are equivocal in this regard. Overall, there is substantial epidemiologic evidence that dietary fiber and whole grain intake is associated with decreased risk of coronary heart disease and some cancers, while the role of legumes in these diseases is promising but inconclusive.

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Dietary guidance recommends consumption of whole grains in the prevention of chronic diseases. Recent studies find that whole grain consumption protects against cardiovascular disease, cancer, and diabetes. Components in whole grains that may be protective are diverse and include compounds that effect the gut environment, e.g. dietary fiber, resistant starch, and oligosaccharides. Whole grains are also rich in compounds that function as antioxidants such as trace minerals and phenolic compounds, and compounds that are phytoestrogens with potential hormonal effects. Whole grains also are rich sources of compounds formerly thought of as antinutrients, for example phytic acid. Phytic acid may function as an antioxidant in human foods and therefore be protective, rather than detrimental to human health. Other potential mechanistic effects of whole grains include binding of carcinogens and modulation of glycemic index. Clearly the range of protective substances in whole grains is impressive and advice to consume additional whole grains is appropriate. Further study is needed on the mechanisms for this protection so the most potent protective components of whole grains are not lost in processing and preparation of whole grains into acceptable foods for the public.

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Ingestion of vegetable protein in place of animal protein appears to be associated with the lower risk for coronary heart disease. This effect may be related to changes in serum lipid concentrations. The cholesterol lowering effects of soy protein as compared with animal protein have been recognized in animal models for more than 80 years. These studies indicate that soy protein intake protects from development of atherosclerosis.

Our group recently completed a meta-analysis of the effects of soy protein intake on serum lipids. We analyzed outcomes reported by 29 controlled clinical studies. In most of these studies, the intake of energy, fat, saturated fat, and cholesterol was similar when the subjects ingested control and soy-containing diets. Soy protein intake averaged 47 grams per day. Ingestion of soy protein was associated with the following net changes in serum lipid concentrations from the concentrations reached with the control diets: total cholesterol, a decrease of 9.3 percent; LDL cholesterol, a decrease of 12.9 percent; triglycerides, a decrease of 10.5 percent; and HDL a nonsignificant increase of 2.4 percent.

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Abstract unavailable.

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There are a number of biologically plausible reasons why consumption of vegetables and fruit might slow or prevent the onset of chronic diseases. Vegetables and fruit are rich sources of a variety of nutrients, including vitamins, trace minerals and dietary fiber, and many classes of non-nutritive, biologically active compounds, such as carotenoids, coumarins, the sulfur-containing dithiolthiones, indoles, isothiocyanates and allyl sulfides, flavonoids, phenols, plant sterols, isoflavones and lignans, and monoterpenes. These substances have complementary and overlapping mechanisms of action, including the induction of detoxification enzymes, stimulation of the immune system, alteration of platelet aggregation, modulation of cholesterol synthesis and hormone metabolism, dilution and binding of carcinogens in the intestinal tract, and antibacterial, antiviral, and antioxidant effects. However, no single compound acts through all proposed mechanisms and, even within phytochemical classes, the biologic activity of compounds varies widely. Consumption of vegetables and fruit contributes variety and complexity to the diet. There is the potential for inhibitory, additive or synergistic biologic interactions of compounds from within one plant food, as well as interactions with other dietary components. Epidemiologic data support the association between a high intake of vegetables and fruit and lowered risk of chronic disease; the complexity of such a diet cannot be ignored in the attempt to understand the mechanisms of action.

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Perhaps one of the most unexpected and novel findings in nutritional epidemiology in the last 5 years has been that nut consumption protects against ischemic heart disease (IHD)--the leading cause of death for male and female adults world-wide. Frequency and quantity of nut consumption has been documented to be higher among vegetarian than in non-vegetarian populations. Nuts also constitute an important part of traditional plant-based diets, such as the Mediterranean and Asian Diets.

In a prospective epidemiological study of approximately 31,000 California Adventists, we found that frequency of nut consumption had a substantial and highly significant inverse association with risk of myocardial infarction and death from IHD. The Iowa Women's Health Study has also documented an association between nut consumption and decreased risk of IHD.

The protective effect of nuts on CHD has been found in both men and women, adults, and the elderly, Caucasion and African Americans. Importantly, nuts have similar associations in both vegetarian and non-vegetarian Adventists. Finally, the protective effect of nut consumption on IHD is not offset by an increased mortality from other causes. Unpublished results from the California Adventist Health Study indicates that frequency of nut consumption is inversely related to all-cause mortality in African Americans and the elderly. Thus, nut consumption may not only offer protection against IHD, but also increase longevity.

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Many studies have shown that reducing saturated fatty acids (SFA) elicits a marked total and low density lipoprotein cholesterol (LDL-C) lowering effect and, as a result, decreases risk of coronary heart disease. The pressing question to be resolved is what nutrient or nutrients should replace SFA calories in the diet? The present report reviews the existing literature that has examined the effects of high carbohydrate, low SFA diets and high fat diets (low SFA) that are high in unsaturated fatty acids with emphasis on studies that have used nuts to achieve nutrient targets. The nuts that have been studied principally have been almonds, which are a rich source of monounsaturated fatty acids (MUFA), and walnuts, which are high in polyunsaturated fatty acids (PUFA). To date, there have been only several studies conducted with nuts. They have been designed to evaluate the effects of nuts on plasma lipids and lipoproteins in diets that are both high and relatively low in total fat.

Collectively the studies that have compared the plasma lipid/lipoprotein responses of a high carbohydrate diet low in SFA to a high fat, high MUFA diet low in SFA (using nuts) have reported similar total and LDL-cholesterol lowering effects. In addition, the high MUFA diet either increased or maintained HDL-cholesterol levels in contrast to the high carbohydrate diet in which a typical HDL-cholesterol lowering effect was observed. There also is evidence to show beneficial plasma lipid/lipoprotein effects of a Step-One diet relatively high in PUFA provided by walnuts. In this study the high walnut diet resulted in even greater reductions in total and LDL-cholesterol levels than did the typical Step-One diet, and the ratio of LDL-cholesterol to HDL cholesterol decreased.

Additional studies are needed to corroborate these findings and to resolve the question of whether there are other biologically active molecules in nuts that promote lipid lowering or confer other beneficial health effects. In this regard, we need to know whether there are distinctive biological effects observed for the different nuts and importantly, what constituents in nuts account for these responses.

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It is estimated that dietary and lifestyle modification could halve the rate of CHD. However, the current dietary guidelines of the AHA (30% fat, 200-300 mg dietary cholesterol) may not be sufficient to stop the progression of coronary heart disease. Hunninghake demonstrated only a 5% improvement in LDL cholesterol from a step 2 AHA diet compared to 27% improvement from lovastatin in the same patients. Patients randomly assigned to the control group in a number of regression trials were consuming a step 1 or step 2 diet, yet the majority of these patients continued to show progression of disease. However, regression of coronary atherosclerosis may occur when dietary intake of fat and cholesterol are much lower.

Dietary intake of fat and cholesterol may have short-term as well as long-term effects, for better and for worse. Even a single high-fat, high cholesterol meal may cause acute enhancement of platelet reactivity as well as sludging in arterial beds. These changes may result from a shift in the thromboxane/prostacyclin balance to favor thromboxane production. In animals with atherosclerosis induced by high-cholesterol diets, platelets synthesize thromboxane A2 in increased amounts. Since cholesterol is contained only in foods of animal origin, a vegetarian diet may shift the balance away from thromboxane formation, which would make both coronary spasm and platelet aggregation less likely to occur.

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We face an obsession in the U.S. that low-fat, high-carbohydrate diets are essential for health, driven largely by an effort to reduce heart disease and more recently certain types of cancer. The "fat phobia" line of reasoning is much clearer for heart disease than it is for cancer. We have learned over the past several years that all fats are not alike, and specifically that saturated fatty acids are more closely associated with risk factors for heart disease. The other broad classifications of dietary fats, polyunsaturated and monounsaturated, do not have as strong an associated risk. An examination of fat-containing foods leads to the conclusion that unsaturated fatty acids are largely found in plant-based foods, and saturated fatty acids in animal foods. In general, plant foods are thought to be rich in carbohydrates, low in fats and low in protein. However, populations that meet all of their nutrition needs from plants, consume plant-based foods that are rich in fat, i.e. nuts, seeds, and oils from plants and seeds, and rich in protein, ie mature beans, peas, and other legumes. Fat is an essential nutrient and, in the body, for example, becomes an important component of cell membranes in the formation of prostaglandins and leukotrienes. The human body can synthesize fat from carbohydrate. Scientists are now beginning to appreciate a relationship between the amount and type of dietary fats to the types of fats found in body fat depots.

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Tuesday, March 25, 1997

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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The relationship of bone mineral density (BMD) and diet continues to be investigated. Evidence suggests a positive relationship with calcium, with protein, particularly from animal sources, appears to be negatively related. Vegetarian populations are of interest because they have lower animal protein intake; however, depending on food choices, their calcium intake may vary considerably. Previous studies of vegetarians primarily investigated lacto-ovo vegetarians and most frequently those in the post-menopausal years. We report BMD results from a study of 50 pre-menopausal women, divided among vegan (n=17), lacto-ovo vegetarians (n=18), and omnivorous (n=15) subjects. Vegetarians had followed their respective diets for at least four years. All subjects were within 20% of ideal body weight, had regular menstrual cycles, engaged in <5hrs/wk of aerobic or strength building exercise, did not consume calcium supplements or take any medications known to affect bone metabolism, including oral contraceptives. The three groups did not differ with respect to age, height, weight and BMI. Percent of expected BMD of the spine as determined by quantitative computed tomography (QCT) was significantly less in vegans (mean±SE) (88 ± 2.7%) compared to LOV (107 ± 3.7%, p<.001) or omnivores (101 ±4.9%, p<.05), but not different between LOV and omnivores.

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Adequate calcium retention is important for building and maintaining peak bone mass. Calcium sources must be evaluated for both calcium content and bioavailability for their role in the diet. Calcium bioavailability from a variety of plant sources have been compared to milk using hydroponically grown vegetables and intrinsic labeling techniques. Generally, plants which contain oxalic acid have poor calcium bioavailability except for soybeans. Plant sources which are low in both oxalic acid and phytic acid typically have better calcium bioavailability than milk although the amount per serving is lower.

Some dietary constituents increase urinary calcium loss, and thus, impact calcium retention even though they do not affect calcium absorption. For every gram of dietary salt consumed, approximately 26 mg calcium is lost in the urine. For every gram of metabolizable protein, approximately 1 mg additional calcium in the urine is lost. Thus, choices present themselves to meet individual needs. Diets can be constructed which are higher in calcium or lower in salt, protein, caffeine, and other constituents which lead to calcium loss.

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It is frequently stated that "menstrual disturbances are more common among vegetarians". Are they? A review of the literature cited to support this statement reveals that most of the cited studies were not specifically designed to address the question. The purpose of this presentation is to critically examine the evidence for and against this supposition. To do this, the normal ovulatory menstrual cycle and the methods used to characterize it will be described, as will clinical and subclinical disturbances of the cycle. Next, the potential for modulation of the menstrual cycle by an array of physiological factors (including nutrition) and psychological stressors will be reviewed. Possible confounding of previous studies by factors such as selective recruitment, introduction of acute dietary changes, and inclusion of subjects with eating disorders, using oral contraceptive agents, or with extreme exercise practices will be discussed. Results of a study that controlled these factors will be reviewed. Although a definitive answer to the initial question cannot be provided in the absence of population studies, the weight of the evidence suggests that vegetarianism per se does not contribute substantially to the development of menstrual disturbances.

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Long chain polyunsaturated fatty acids (LCP) derived from linoleic acid (18:2n-6) and linolenic acid (18:3n-3) respectively are required for normal development of the retina and central nervous system but the extent to which they can be synthesized from the parent fatty acids is debated. LCP are generally absent from plant foods although there are some novel algal sources. The developing fetus obtains LCP from the mother by selective uptake from the maternal plasma. LCP are also found in breast milk and are believed to contribute towards the needs of the developing brain. The proportion of n-6 LCP is greater and that of n-3 LCP is lower in vegetarians than meat-eaters. This difference is probably a consequence of the selection of foods with a high ratio of n-6/n-3 fatty acids by vegetarians. It is uncertain whether the brains of vegetarian infants contain less docosahexaenoic acid. On the basis of experiments in primates, it may be prudent to recommend diets with a ration of linoleic/linolenic acid of between 4:1 and 10:1 in vegetarians.

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Human beings evolved on a diet that contained about equal amounts of omega-3 and omega-6 fatty acids. Over the past 100-150 years there has been an enormous increase in the consumption of omega-6 fatty acids due to the increased intake of vegetable oils from corn, sunflower, safflower, cotton seed and soya (soybean). Today in Western diets, the ratio of omega-6 to omega-3 fatty acids is about 15-20/1 instead of 1-2/1. Studies indicate that omega-3 fatty acids are essential for growth and development and have antiinflammatory, antithrombotic, antiarrhythmic, hypolipidemic and vasodilatory properties. Their beneficial effects have been shown in some patients with renal disease, rheumatoid arthritis, ulcerative colitis, Crohn's disease, chronic obstructive pulmonary disease, diabetes, and in the prevention and management of coronary heart disease and blood pressure. Although most of the studies have been carried out with fish oils (eicosapentaenoic acid, EPA and docosahexaenoic acid, DHA), alpha linolenic acid (LNA) found in green leafy vegetables, flaxseed, rapeseed, and walnuts, desaturates and elongates in the human body to EPA and DHA. However, LNA by itself may have beneficial effects in health and in the control of chronic diseases.

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The available evidence does not support either a beneficial or detrimental effect of a vegetarian diet upon physical performance capacity, especially when carbohydrate intake is controlled. Concerns have been raised that an emphasis on plant foods to enhance carbohydrate intake to optimize body glycogen stores may increase dietary fiber and phytic acid intake to levels that reduce the bioavailability of several nutrients, including zinc, iron, and some trace minerals. There are no convincing data, however, that vegetarian athletes suffer impaired nutrient status from the interactive effect of their heavy exertion and plant-food based dietary practices, at least enough to impair performance and/or health. Although there has been some concern about protein intake for vegetarian athletes, data indicate that all essential and nonessential amino acids can be supplied by plant food sources alone as long as a variety of foods is consumed and the caloric intake is adequate to meet energy needs. Creatine, found in uncooked meat, has been urged as an ergogenic aid to athletes who perform repeated bouts of short-term high intensity exercise. However, further laboratory and field research is needed to help resolve the conflicting findings regarding the ergogenic efficacy of creatine. There has been some concern that vegetarian female athletes are at increased risk for oligo-amenorrhea, but evidence suggests that low energy intake, not dietary quality, is a major cause. In conclusion, the vegetarian diet per se is not associated with improved aerobic endurance performance. Although some concerns have been raised about the nutrient status of vegetarian athletes, a varied and well-planned vegetarian diet is compatible with successful athletic endeavor.

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Vitamin supplementation is prescribed for renal failure patients, including dialysis patients, because restricted diet, uremic toxins, drug effects, and the process of dialysis increase the risk of frank or subclinical vitamin deficiency. The appropriate level of supplementation of folic acid has been controversial. The increased requirement for pyridoxine, vitamin B6 to normalize serum levels of its active moiety, pyridoxal phosphate, is generally unrecognized. Data are rapidly acumulating suggesting that vitamins B6 (Pyridoxine) and B12 (cobalamin) as well as folic acid may play a protective role in normalizing homocysteine metabolism, thereby preventing its accumulation in excessive amounts in blood and urine. Renal failure patients tend to have high serum homocysteine levels and a high rate of cardiovascular disease. Appropriate and as yet undefined levels of supplementation with folic acid, pyridoxine, and cobalamin may decrease the risk of cardiovascular disease related to the homocysteine risk factor.

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Certain whole and unrefined foods such as sun-dried raisins, nuts, sesame seeds, whole grains, and green and orange vegetables and fruits contain high levels of antioxidant phenolics, fiber, and other phytochemicals recognized as being protective against chronic diseases. High rates of some cancers, heart disease, and poor colon function in industrialized countries are related to typical western diets high in animal foods, refined grain products and sugars. To study the effects of a typical western diet and one based on whole and unrefined foods (WUF) on lipoproteins, antioxidant defenses, and intestinal function, 12 hyperlipidemic women for four weeks consumed a diet low in fruits, vegetables and whole grains and then for four weeks consumed a diet rich in foods such as orange and green fruits and vegetables, whole grains, sun-dried raisins, nuts, sesame seeds, and olive oil. Calorie and fat intake were similar for both diets with saturated fat dropping by about one-third and fiber increasing by 159% on WUF. Tocopherols, other phenolics and carotenoids increased by about 500% and vitamin C by about 130%. WUF induced a drop of 16% (p<0.001) in low density lipoprotein and 19% in triglycerides, with no change in high density lipoproteins. Red cell superoxide dismutase decreased by 69% (p<0.01) and plasma glutathione peroxidase dropped 35% (p<0.01). Colonic function was improved on WUF. These changes indicate that the WUF diet decreased the need for oxidative defense mechanisms while inducing salutary effects on lipoproteins and colonic function.

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As part of the Adventist Ministers' Health Study, the serum Vitamin B12 (B12) status of 330 Australian and New Zealand Seventh-day Adventist Ministers was monitored in 1994 and February 1997 (along with a Biochemical profile including lipid studies, full blood count and detailed confidential lifestyle and diet questionnaire). The vast majority of the Ministers in the study, who participated voluntarily, are lacto-ovo vegetarians. This study has been jointly undertaken by the Adventist Church Administration in the South Pacific, and Sydney Adventist Hospital.

From the accumulated data, a reference range for B12 for lacto-ovo vegetarians has been established. Australia and New Zealand are Western Countries with a culture and living standard that closely resembles North America. Hence, it is likely that the observations from this group will be relevant to other Western countries.

The initial study in 1994 (sample 195) revealed 51% had serum B12 levels below the reference range. (Published Reference range for B12 is 171-840 pmol/L). The observed range was 68 to 744 pmol/L. The 1997 study (sample 327) revealed 54% had B12 levels below the reference range.As part of the Adventist Ministers' Health Study, the serum Vitamin B12 (B12) status of 330 Australian and New Zealand Seventh-day Adventist Ministers was monitored in 1994 and February 1997 (along with a Biochemical profile including lipid studies, full blood count and detailed confidential lifestyle and diet questionnaire). The vast majority of the Ministers in the study, who participated voluntarily, are lacto-ovo vegetarians. This study has been jointly undertaken by the Adventist Church Administration in the South Pacific, and Sydney Adventist Hospital.

From the accumulated data, a reference range for B12 for lacto-ovo vegetarians has been established. Australia and New Zealand are Western Countries with a culture and living standard that closely resembles North America. Hence, it is likely that the observations from this group will be relevant to other Western countries.

The initial study in 1994 (sample 195) revealed 51% had serum B12 levels below the reference range. (Published Reference range for B12 is 171-840 pmol/L). The observed range was 68 to 744 pmol/L. The 1997 study (sample 327) revealed 54% had B12 levels below the reference range.

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This study was designed to investigate dietary intake and nutritional status of vegans compared to omnivores. Twenty five vegans and twenty omnivores completed four days of food records. Selected biochemical, hematological and immune status parameters indicative of nutritional status were measured on all participants. Vegans were significantly lower than omnivores for serum ferritin, white blood cells, lymphocytes, immunoglobulin A and complement 3. Mean serum methylmalonic acid was higher in the vegan group and a number of individuals in the group had indicators suggestive of vitamin B-12 deficit. Other nutritional, biochemical, and hematological differences were noted and the implications of these will be discussed.

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Herbs have been used as food and for medicinal purposes for centuries. Today much research interest focuses upon various herbs that possess hypolipidemic, antiplatelet, antitumor or immune-stimulating substances that may significantly reduce the risk of cardiovascular disease and cancer. A whole variety of active phytochemicals have been identified in different herbs including the flavonoids, terpenoids, lignans, sulfides, polyphenolics, carotenoids, coumarins, saponins, curcumins and phthalides. A variety of these phytochemicals stimulate the activity of the Phase I and 11 enzymes such as glutathione-S-transferase. Most of the active phytochemicals possessing phenolic structures are related via the shikimic acid pathway. Discussion will focus upon the biochemical activity of the Allium, Labiatae, Umbelliferae and Zingeriberaceae families as well as flaxseed, licorice root, and green tea. Many of these herbs naturally possess very potent antioxidant compounds that provide significant protection against disease. These antioxidants may protect LDL cholesterol from oxidation, inhibit cyclooxygenase and lipoxygenase enzymes, inhibit lipid peroxidation, have antiviral or antitumor activity. The volatile essential oils of commonly used culinary herbs and spices and herbal teas inhibit mevalonate synthesis and thereby suppress cholesterol synthesis and tumor growth.

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We documented publication trends of vegetarian nutrition articles in the biomedical literature between 1966 and 1995, using the Medline bibliographic data base. The publication rate of vegetarian articles increased steadily during the three decades, from an average annual rate of less than 10 in the late 1960's to more than 70 in the early 1990's. A fluctuating but steady increase of published vegetarian nutrition articles has also been observed in nutrition journals indexed by Medline during this period, from <5/year to 35/year. After adjusting for the total number of articles published annually in nutrition journals or indexed in Medline, it was observed that the vegetarian literature experienced a dramatic growth during the 1970's, reaching an oscillating plateau during the 1980's. In the early 1990's, the proportion of vegetarian nutrition articles was approximately 8/1,000 published articles in the nutrition literature and about 20/100,000 indexed articles by Medline. Over the years, the nature and study design of published vegetarian research has changed. While case histories and case series were almost exclusively published in medical journals (19% of the total), nutrition journals published a higher proportion of group comparison, cross-sectional studies, and clinical trials.

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Only a few studies have focused on the physical growth, pubertal development, and the physical fitness of vegetarian children, adolescents and young adults. Therefore, this study was designed to assess average daily dietary intakes of food energy in vegetarian children (n=48) (Group 1: 6-10 y-old girls and 6-12 y-old boys), adolescents (Group 2: 10-16 y-old girls and 12-18 y-old boys), and young adults (Group 3: >16-33 y-old girls and >18-30 y-old boys). The study also included determination of body height and weight, triceps, suprailiac and calf skinfolds, puberty ratings, and physical fitness variables. Food energy intake was lower in all three groups, particularly in the 15 y-old boys and girls (respectively 66% and 51% of the recommended uptake) and also in Group 3 both in the male (68%) and female subjects (75%). Body height and weight did not differ significantly from the reference data except for Group 2 (12-18 y-old boys) who had significantly (P<0.05) lower body height and weight. Triceps and suprailiac skinfolds were significantly (P<0.05) lower in all age groups, while calf skinfold was only significantly (P<0.05) lower in the 10-16 y-old females. The vegetarian subjects were not different in physical fitness from the reference population, except for the group of 12-18 y-old boys who scored significantly (P<0.05) lower in hand dynamometry, 30 sec. sit-up test, and both the girls and boys of Group 2 scored significantly lower in the standing broad jump. In the step test there was no difference between the vegetarian groups and a reference population. Puberty ratings scaled on Dutch percentile graphs showed that all vegetarian subjects, except for 1 girl, were within the normal developmental limits (P3-P97) of their respective age group. It may be concluded that within the limits of this study, the vegetarian subjects have lower body weight and skinfold thickness at adolescence and they score lower in the strength related tests when compared to reference norms. The growth and maturity status of the vegetarian population were within the normal range of the reference general population.

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The first step toward vegetarian diets and vegetarian nutrition is consumer dietary choice. Researchers from many clinical and social sciences are interested in dietary choice, but have not combined their research into a comprehensive model to explain consumer actions. No model has offered a good explanation for the "paradox of dietary change." Many people successfully change their diet significantly (often toward health-improving, plant-based diets) and are happy with the change and yet dietary change is often perceived by the public and health professionals as difficult and unlikely to succeed.

Using the emerging science of complex systems analysis, I have developed a model that describes dietary decisions for individuals and predicts outcomes for society as a whole. The predictions suggest methods for helping society shift toward plant-based diets.

Complex systems offers an intuitive method for studying evidence about dietary choice from many fields, including public health, clinical sciences, economics, sociology, marketing, and genetics, and for combining individual choice with social interaction. Previous models have looked at only a few influences, and have had to focus on either individuals or social aggregates without being able to effectively combine them. My model suggests an explanation for the paradox and methods for intervention. In particular, it suggests how and why major changes might be easier than incremental ones. These results have important implications for how clinical nutritionists and public health policy makers can best encourage the consumption of healthy vegetarian diets.

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Vegetarianism in India dates back 3000 years. Vegetarian ethos was propounded by Vedic Indians as early as 1000 BC. Vegetarian eating exists for as long as a hundred generations.

Two major factors are involved in Vegetarianism in India: (a) ethical or religious beliefs; and (b) income considerations. Vegetarian food habits are also geographically oriented. Living in cities influences the nature of food intake. Rural Indian food is every part of the country is essentially vegetarian. Food items like cereals, pulses, wheat, rice, roots and tuber crops are noticeable components of such diets.

Due to the prevalence of dietary fibre in Indian vegetarian menu, incidence of diseases of lower colon and constipation are less prevalent. Fermented cereals and milk (curd) are common ingredients in vegetarian diets and provide probiotic protection through easy digestibility. Consumption of fresh sprouting seeds like mungbean and green gram are a well established sources of Vitamins C and the B-group, and an age-old practice which should find modern nutritional vindication. In the Aryan ethos, two kinds of foods like Kachha food and Pacca foods serve as the basis for sound nutritional practice. India also has a long tradition of using unsaturated vegetable oils in daily cooking. Ghee (heat clarified butter) is a ubiquitous supplement in Indian food. The raw preparation of plant foods made up of ground green bio-ingredients is a long-cherished distinct Vedic practice and known as "cooking without fire."

Vegetarianism can be the ideal choice. The reasons include the nutritional advantages and good sources of protein. It also offers a competitive advantage for land use. It is encouraging to note that starting from Tolstoy, Einstein, Shakespeare, Newton and continuing to Mahatma Gandhi (India), all were vegetarians. To preserve health and environment, the people of the world should prefer a vegetarian diet.

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This study estimates the potential Medicare and total health care savings that would be expected if all Americans were vegetarians. The prevalence of major illness among omnivores and vegetarians is compared in studies which have controlled for other lifestyle factors, and the corresponding attributable health care savings are calculated in 1994 dollars. When it is assumed that health care savings from vegetarian diets are equal to the difference in health care costs of omnivores and vegetarians, the annual Medicare savings potentially attributable to vegetarian dietary practices are $9.8-10.1 billion for heart disease, cancer, diabetes, gallstones, kidney stones, and appendicitis. The total annual health care savings attributable to vegetarian dietary practices are estimated at $31.5-67.5 billion for hypertension, heart disease, cancer, diabetes, gallstones, obesity, and foodborne illness. Health care savings potentially attributable to vegetarian dietary practices are quantifiable and substantial.

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The idea that dietary factors may influence rheumatoid arthritis (RA) has been a part of the folklore of the disease, but scientific support for this view has been sparse.

In a controlled single blind trial, we tested the effect of fasting for 7-10 days followed initially by an individually adjusted gluten-free vegan diet for 3.5 months and subsequently by an individually adjusted lactovegetarian diet for 9 months. For all clinical variables and for most of the laboratory variables, the 27 patients who were randomized to fasting and vegetarian diet improved significantly compared with the 26 patients in the control group, who followed their usual omnivorous diet throughout the study period. One year after the patients had completed the trial, they were re-examined, and the improvements compared with trial entry were significantly more pronounced in the vegetarians who previously benefited from the diet (diet responders) compared with diet non-responders and omnivores.

The beneficial effect could not be explained by patients' psychological characteristics, by antibody activity against food antigens, or changes in the levels of prostaglandin and leukotriene precursors. However, the fecal flora differed significantly between samples collected at time points where there was a substantial clinical improvement and time points with no or only minor improvement.

In summary, the results show that a proportion of patients with RA can benefit from a fasting period followed by a vegetarian diet. Thus, dietary treatment may be considered a valuable adjuvant to the ordinary therapeutic armamentarium in RA.

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Abstract unavailable.

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Parkinson (PD) patients are instructed to restrict daytime dietary protein to minimize amino acid absorption competition with DOPA blood barrier absorption. This instruction is given because animal protein with high branched chain amino acid levels (BCAA), competes for DOPA absorption sites on the blood brain barrier. We propose substitution of plant protein with its lower BCAA content for animal protein to minimize this competition. Two liquid test meals, with equal carbohydrate and fat content, but 40 gm of either casein from milk (CTM) or soy protein (STM) are given between 8 and 10 a.m. on two different days nine weeks apart. Eight PD patients participated who are between 66-80 years and had been on Sinemet for 5 or more years and had experienced varying "on-off" symptoms. We have previously described the insulin, glucose and glucagon assays (Atherosclerosis 1989; 76:55-61), and likewise the DOPA and 3MD assays (FASEB J 1996:10:#3 a-486 #2803).

Patients were given their usual Sinemet dose (between 100 to 250 mg/dose) 15 minutes before one or other of the two test meals were consumed. Plasma DOPA values were consistently, though not sigificantly, higher from 15 to 120 minutes after CTM. Leucine, insulin and glucagon levels were all significantly higher after CTM in comparison to STM from 15 to 90 minutes after the start of the test meals. 3-Methyldopa (3MD), a direct absorption competitor of DOPA, gave higher mean levels (p<0.02) after the CTM versus STM. Plasma DOPA increases after CTM, although not statistically significant, may be the direct result of the significant increases in 3MD.

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Wednesday, March 26, 1997

Data for 27,808 vegetarians and 48,364 non-vegetarians in five prospective studies were pooled. Mortality ratios at ages 16 to 89, adjusted for age, sex, smoking and study, were calculated by Poisson regression. After a mean of 10.6 years of follow up there were 8,330 deaths before age 90. In comparison with non-vegetarians, vegetarians had a 25% reduction in mortality from ischaemic heart disease (rate ratio 0.75, 95% confidence interval 0.68-0.82, p<0.00001). This reduction in mortality among vegetarians varied with age at death: rate ratios were 0.52 (95% CI 0.38-0.71), 0.71 (95% CI 0.62-0.81) and 0.86 (95% CI 0.75-0.98) for deaths from ischaemic heart disease at ages <65, 65-79 and 80-89 respectively. Mortality rate ratios in vegetarians compared to non-vegetarians were 1.00 (95% CI 0.78-1.29) for colorectal cancer, 1.02 (95% CI 0.76-1.35) for breast cancer and 0.89 (95% CI 0.61-1.29) for prostate cancer. For all causes of death the rate ratio for vegetarians was 0.91 (95% CI 0.87-0.96, 2p<0.001), largely due to their lower mortality from ischaemic heart disease. We conclude that vegetarians have a lower risk of dying from ischaemic heart disease than non-vegetarians. There is no evidence from this analysis that a vegetarian diet alters the mortality rates for cancers of the colorectum, breast or prostate.

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The Oxford Vegetarian Study has a cohort of around 6,000 non-meat eaters and around 5,000 meat eaters who have been studied since the early 1980's. In this paper the 14-year mortality follow up of the study participants is reported. There was a significant 38% reduction in mortality from ischaemic heart disease in vegetarians as compared with those who ate meat regularly but no difference in mortality from non-IHD causes of death. The participants completed a brief food frequency questionnaire at recruitment, and the relative risk of ischaemic heart disease mortality was estimated according to reported consumption of selected foods and intake of fat and fibre. Consumption of animal fat showed a strong relationship with risk of death from ischaemic heart disease with those in the highest tertile of animal fat consumption having a more than twofold increase in risk. There were no convincing relationships between risk of IHD death and consumption of dietary fibre or fruit, nuts and vegetables.

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In 1976, food frequency data was collected from 34,192 California Seventh-day Adventists. These subjects were then followed for 6 years to find all cases of incident coronary artery disease and cancer, and for 13 years to find all deaths.

For nearly all endpoints, vegetarians had lower risk then non-vegetarian Adventists. Frequent consumption of legumes was associated with reduced incidence of pancreatic cancer, and colon cancer (amongst non-vegetarians); frequent consumption of fruit was associated with lower incidence of lung, pancreatic, and prostate cancer. Consuming nuts 4-5 times per week was associated with a halving of coronary event risk, and a preference for whole grain bread was associated with 30% lower risk of these events. Frequent consumption of red meats was associated with higher rates of bladder cancer, and in men, fatal coronary events. Frequent consumption of white and red meats was associated with higher incidence of colon cancer (when legume consumption was low). Higher intake of polyunsaturated fats was associated with lower frequency of incident coronary events and also prostate cancer. Consequently, the advantages of a vegetarian diet seem to be both due to higher consumption of legumes, fruits, and polyunsaturated fats, as well as the lower consumption of meats.

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