Scientific Update
A Review of Recent Scientific Papers Related to Vegetarianism
By Reed Mangels, PhD, RD, FADA
Food Guide Pyramid for Young Children Includes Vegetarian Foods
The USDA recently released a Food Guide Pyramid for Young Children 2 to 6 years old. The booklet which accompanies the pyramid, called Tips for Using the Food Guide Pyramid for Young Children, includes 1 cup of calcium-fortified soymilk in the Milk Group and 1/2 cup of tofu or 1 soy burger patty (as well as cooked dried beans) in the Meat Group. This could be a useful tool to send to your child's daycare or pre-school in place of the food pyramid which is commonly used and which does not include soy milk or soy burgers. The graphic and booklet may be downloaded from the home page of the USDA Center for Nutrition Policy and Promotion on the World Wide Web. The URL for the home page is www.usda.gov/cnpp.
News from the Third International Congress on Vegetarian Nutrition
The Third International Congress on Vegetarian Nutrition was held in 1997 in Loma Linda, CA. A supplement to the September 1999 American Journal of Clinical Nutrition reported on the proceedings of this symposium. This publication includes many reviews of different aspects of vegetarian nutrition. Here are a few highlights:
Researchers from four different countries combined data from five studies of vegetarians compared to non-vegetarians (1). A total of 27,808 vegetarians were studied. Vegetarians had a 24% lower mortality from heart disease than did non-vegetarians. There was no significant difference in mortality from cerebrovascular disease, stomach cancer, colon cancer, lung cancer, breast cancer, or prostate cancer in vegetarians when compared to non-vegetarians.
A study of 6,000 vegetarians in the United Kingdom found that vegans had lower blood cholesterol and LDL-cholesterol levels than did meat eaters; values for vegetarians (not vegans) and fish eaters were in between and similar to each other (2). Death rates for all causes, and for heart disease and cancer, were lower in non-meat-eaters (vegetarians or those who ate meat occasionally or ate fish) than in meat eaters.
Vegetarian Seventh-Day Adventists had lower risk of having diabetes, hypertension, colon and prostate cancer, and arthritis than did non-vegetarian Seventh-Day Adventists (3). Obesity increased as meat consumption increased. Use of nuts 4-5 times per week appeared to reduce risk of heart disease.
Following a vegetarian diet does not necessarily reduce the amount of calcium lost in the urine if protein intake is similar to that of non-vegetarians or if the diet is high in sulfur-containing amino acids (from cereals, nuts, seeds, fruit) (4). Vegetarians can choose to use a lower protein, lower sulfur-containing amino acid diet to reduce their calcium requirement. For many, compliance with this type of diet could be difficult because of the limited variety of food choices. An alternative would be to use liberal amounts of dietary calcium to offset calcium losses.
A study of 25 California vegans found that they tended to have diets which were lower in fat, saturated fat, and cholesterol and higher in fiber than those of non-vegetarians (5). Vegan diets were also higher in vitamin C and folate. Vegans were leaner than non-vegetarians.
The number of articles on vegetarian nutrition in professional publications has increased from an average of less than 10 per year in the late 1960s to 76 per year in the early 1990s (6). More research and review articles are being published and fewer case studies and letters to the editors. Twenty years ago, the focus of the majority of articles was the nutritional adequacy of vegetarian diets; today the focus is more on the use of vegetarian diets in prevention and treatment of chronic disease.
1. Key, T.J., Fraser, G.E., Thorogood, M., et al. 1999. Mortality in vegetarians and non-vegetarians: detailed findings from a collaborative analysis of 5 prospective studies. Am J Clin Nutr 70(suppl):516S-524S.
2. Appleby, P.N., Thorogood, M., Mann, J.I., Key, T.J.A. 1999. The Oxford Vegetarian Study: an overview. Am J Clin Nutr 70(suppl):525S-531S.
3. Fraser, G.E. 1999. Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California Seventh-Day Adventists. Am J Clin Nutr 70(suppl):532S-538S.
4. Weaver, C.M., Proulx, W.R., Heaney, R. 1999. Choices for achieving adequate dietary calcium with a vegetarian diet. Am J Clin Nutr 70(suppl):543S-548S.
5. Haddad, E.H., Berk, L.S., Kettering, J.D., et al. 1999. Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians. Am J Clin Nutr 70(suppl):586S-593S.
6. Sabate, J., Duk, A., Lee, C.L. 1999. Publication trends of vegetarian nutrition articles in biomedical literature, 1966-1995. Am J Clin Nutr 70(suppl):601S-607S.
We'll Say It Again, "Choose Whole Grains!"
Not too long ago, we reviewed studies in which post-menopausal women with the highest intake of whole grains (three servings per day) had the lowest risk of dying from heart disease, had a lower death rate over the nine years of the study, and had a lower risk of dying from cancer. If that's not enough to convince you, a recent study of more than 75,000 women found that whole grain intake was associated with reduced risk of developing heart disease. These results could not be completely explained by the women's higher intake of fiber, folate, vitamin B-6, or vitamin E, suggesting that there is something to be said for using whole grains rather than taking supplements.
Liu A., Stampfer M.J., Hu F.B., et al. 1999. Whole-grain consumption and risk of coronary heart disease: results from the Nurses' Health Study. Am J Clin Nutr 70:412-419.
Changes in Eating Habits of Asian Indians Living in the United States
In the past 35 years, more than 800,000 Asian Indians have settled in the United States. Their traditional diet is often based on grains, legumes, fruits, vegetables, and dairy products. Has their way of eating changed since they moved to the US? A small study of 73 Asian Indian adults living in New York City and Washington, DC, attempted to identify trends. More than a third of those surveyed were vegetarian, generally either lacto-ovo or lacto vegetarian. Typical diets of those surveyed included rice, dal (cooked dried beans), roots like potatoes, yogurt, coffee, broiled Indian bread, and pickled fruits and vegetables. Close to one half of the respondents never ate hot dogs or hamburgers. Use of other meat, fish, poultry, or butter either had increased since moving from India or stayed the same. Asian Indians tend to be at increased risk for developing diabetes and heart disease. Perhaps use of a more traditional Indian vegetarian diet, replacing higher fat foods with those lower in fat, could help to reduce this risk.
Raj, S., Ganganna, P., Bowering, J. 1999. Dietary habits of Asian Indians in relation to length of residence in the United States. J Am Diet Assoc 99:1106-1108.
The Nutritional Status of Vegetarian Women in Australia
Researchers from Deakin University in Australia compared 50 vegetarian women aged 18 to 45 years with 24 non-vegetarian women. The vegetarian women had lower intakes of protein, saturated fat, and cholesterol and higher intakes of fiber and vitamin C. Their diets were said to be closer to those recommended for healthy eating than the diets of omnivores. Iron intakes of both groups were similar and were below the Australian recommended dietary intake for iron. Vegetarian women had lower levels of ferritin, on average, in their blood than did non-vegetarians. Similar percentages of vegetarians and non-vegetarians had low ferritin levels, however. Ferritin is the form in which iron is stored in the body, so low levels indicate that less iron is stored. Low stores increase the risk of becoming anemic at times of stress or excessive blood loss. The researchers point out that all women need good sources of iron.
Ball, M.J., Bartlett, M.A. 1999. Dietary intake and iron status of Australian vegetarian women. Am J Clin Nutr 70:353-358.
