Vegetarian Congress research presentations

Research presentations

Tuesday, March 25, 1997

# 12

Bone Health Around the World John JB Anderson

An increase of the prevalence of hip fractures has been observed world-wide, and especially steep rises have been reported in newly affluent nations like Hong Kong and Singapore. A major factor in the rise in fractures has been the increasing life expectancy of women (and also men) in affluent and newly affluent nations since the end of World War II. Both the greatly improved nutritional status of many people throughout the world and the control of infectious diseases have contributed to the aging of many nations. The crisis of hip fractures will probably continue until the third or fourth decade of the 21st Century because of the increasing percentages of older people in the population.

Emphasis will be placed on preventive strategies, including nutrition, physical activity, and other healthy lifestyle variables that can be promoted. Dietary factors will become increasingly important, and not simply calcium in promoting bone health and preventing osteoporotic fractures. New information is emerging, for example, about the potential beneficial role of plant molecules to bone health. The phytoestrogens, such as genistein and daidzein, found in soybeans and their products are being tested in humans to uncover the significance of their bone preserving role in prospective interventions. A new approach for the potential to prevent or delay hip fractures is now upon us and only new information from human studies will enable us to utilize these non-nutrient food molecules from plant sources in a safe and rational manner.

# 13

Bone Mineral Status in Vegan, Lacto-ovo Vegetarian and Omnivorous
Pre-Menopausal Women -- Patricia Johnston

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.

# 14

Making Choices Within a Vegetarian Diet for Achieving Adequate Calcium -- Connie Weaver

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.

# 15

Vegetarianism and the Menstrual Cycle: Is There an Association? -- Susan Barr

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.

# 16

Essential Fatty Acids in Pregnancy, Lactation, and Infancy -- T.A.B. Sanders

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.

# 17

Essential Fatty Acids in Health and Chronic Disease -- Artemis Simopoulos

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.

# 18

Physical Fitness and Vegetarian Diets: Is There a Relationship? David Nieman

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.

# 19

Homocysteine and Heart Disease -- Rhoda Makoff

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.

# 20

The Benefits of Phytochemicals and Fiber from Plant Foods on Lipid Metabolism, Antioxidant Defenses, and Colon Function -- Bonnie Bruce

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.

# 21

Adventist Ministers' Health Study: Vitamin B12 Issues -- Bevan Hokin

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.

# 22

Dietary, Biochemical, Hematological, and Immune Status of Vegans -- Ella Haddad

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.

# 23

The Health Promoting Properties of Common Herbs -- Winston Craig

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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