Scientific Update

By Reed Mangels, PhD, RD

Metabolic Syndrome Less Likely in Those Eating a Mostly Vegetarian Diet

Metabolic syndrome is a group of conditions that include high blood pressure, high blood sugar, and too much body fat. Someone who has metabolic syndrome is at higher risk for heart disease and diabetes.

Recently, researchers from Loma Linda University used data from a large study of Seventh-day Adventists to examine the relationship between dietary patterns and metabolic syndrome. Approximately half of their subjects ate meat regularly, a sixth ate fish regularly, and a third ate a mostly vegetarian diet (meat, poultry, and fish less than once a month). The group eating a mostly vegetarian diet had the lowest Body Mass Index (BMI) and had lower blood pressure, blood sugar, and waist circumference than meat-eaters. Compared to meat-eaters, those consuming a mostly vegetarian diet had approximately a 56 percent lower risk of metabolic syndrome. Once again, a vegetarian dietary pattern was associated with a lower risk of health problems.

Rizzo NS, Sabate J, Jaceldo-Siegl K, et al. 2011. Vegetarian dietary patterns are associated with a lower risk of the metabolic syndrome. Diabetes Care 34:1225-27.

High-Fiber, Vegetarian Diets Associated with a Reduced Risk of Diverticular Disease

If you have either diverticulosis or diverticulitis, you are considered to have diverticular disease, which affects the large intestine. In diverticulosis, pouches called diverticula form in your large intestine. Diverticulitis occurs when the pouches become inflamed. Approximately half of adults between 60 and 80 years of age in the U.S. have diverticular disease.

A low-fiber diet is believed to be a major cause of this disease because it often leads to constipation and to bowel muscles having to strain to pass stool. This straining can lead to diverticula forming.

British researchers studied more than 47,000 men and women, approximately a third of whom reported that they ate a vegetarian diet. Over a follow-up period of nearly 12 years, vegetarians (including vegans) had a 30 percent lower risk of developing diverticular disease compared to non-vegetarians who ate either meat or some fish but no meat. If vegans are examined separately, their risk of diverticular disease is even lower, with a 62 percent lower risk compared to non-vegetarians. (Note that these results are based on a small number of vegans.) Higher amounts of dietary fiber, as might be expected, were also associated with a lower risk of diverticular disease, but only in meat-eaters. The vegetarians' lower incidence of diverticular disease could not be explained by their higher fiber intake; perhaps other components of a vegetarian diet are protective or something in a diet containing meat and fish increases diverticular disease risk.

Crowe FL, Appleby PN, Allen NE, Key TJ. Diet and risk of diverticular disease in Oxford cohort of European Prospective Investigation into Cancer and Nutrition (EPIC): prospective study of British vegetarians and non-vegetarians. BMJ 2011 Jul 19; 343:d4131.

Vegans Should Be Aware of Good Sources of Iodine

Iodine is necessary for the thyroid gland to function normally. Studies have reported that the iodine intakes of vegans in several countries are lower than those of non-vegetarians. Staples of a vegan diet — including most fruits, vegetables, and nuts — are low in iodine, even though their iodine content varies depending on the soil in which they're grown and irrigation and fertilization practices.

A recent study examined the iodine intake and status of 78 vegetarians and 63 vegans in the Boston area. Most subjects did not use a vitamin-mineral supplement containing iodine and had not used iodized salt recently. Urine levels of iodine were significantly lower in the vegans, suggesting that this group is at risk for inadequate iodine intake.

Pregnant women should be especially careful to have adequate iodine because this nutrient plays a role in fetal brain development. The American Thyroid Association recommends that pregnant and breastfeeding women take a prenatal supplement that contains at least 150 micrograms of iodine daily.

Vegans can get iodine from iodized salt, iodine supplements, and sea vegetables, although the amount of iodine in sea vegetables varies. More information about iodine in the vegan diet can be found at <>.

Leung AM, LaMar A, He X, et al. 2011. Iodine status and thyroid function of Boston-area vegetarians and vegans. J Clin Endocrin Metab 96: E1303-7.

What's New with WIC?

Established in 1972, the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) was developed to protect the health of low-income pregnant and postpartum women, infants, and children up to age 5. The program provides vouchers to purchase specific foods that are identified as being nutritious. More than 9 million people receive WIC benefits each year. Although the U.S. Department of Agriculture (USDA) administers the program, state agencies make decisions about which foods are included in their state’s program.

In 2007, the USDA markedly revised the foods that can be included in the WIC food package. One key change for vegans and others who do not use dairy products was that soy beverages and calcium-set tofu with specific levels of certain nutrients can be substituted for cow’s milk. Medical documentation is required for this substitution to be allowed for children. Currently, 71 percent of state agencies allow soymilk to replace cow’s milk, and 40 percent allow tofu to replace cow’s milk. Of those state agencies that allow soy beverages, approximately half permit refrigerated soymilk, while the other half allow either refrigerated or shelf-stable soymilk.

Another change was that WIC vouchers for fruits and vegetables can be used at farmers' markets. So far, thirteen states and the District of Columbia have adopted this policy.

Also, states can allow brown rice, corn or whole wheat tortillas, bulgur, barley, or oatmeal to replace whole wheat bread. This allows for more culturally diverse foods. Ninety percent of state agencies allow brown rice, while 82 percent allow tortillas. Bulgur, barley, and oatmeal are less commonly authorized.

VRG submitted comments to the USDA supporting the revisions to the WIC food packages. Not only would the proposed changes improve the nutritional quality of the program's food, but we believe that the program should add more foods acceptable to vegetarians and vegans. It's gratifying to see these changes being implemented in many states, although we're concerned that tofu and soymilk are not available in every state.

To learn more about the WIC program in your state, see the full text of the report at <>.

Cole N, Jacobson J, Nichols-Barrer I, Fox MK. Robare JF, Project Officer. U.S. Department of Agriculture, Food, and Nutrition Service, Office of Research and Analysis, WIC Food Packages Policy Options Study. USDA: Alexandria, VA: June 2011.

And Yet Another Strike Against Red Meat

It's almost become old hat. Study after study reports that red meat is associated with an increased risk of colon cancer and heart disease, and now there's more. Higher intakes of red and processed meat are associated with an increased risk of developing type 2 diabetes.

A study of more than 200,000 people found a strong and consistent relationship between the intake of red and processed meat and the risk of developing diabetes. The researchers estimated that, if one serving of red meat per day was replaced with a serving of nuts, the risk of type 2 diabetes would be 21 percent lower. Replacing one serving of red meat per day with a serving of whole grains was estimated to reduce the risk by 23 percent. However, substituting a serving of red meat with a serving of fish or poultry had less of an effect on type 2 diabetes risk reduction than did replacing red meat with either nuts or whole grains.

Nearly 2 million new cases of diabetes occur each year in the United States; some of these could be prevented by replacing red and processed meats with plant foods, including nuts and whole grains.

Pan A, Sun Q, Bernstein AM, et al. 2011. Red meat consumption and risk of type 2 diabetes: 3 cohorts of U.S. adults and an updated meta-analysis. Am J Clin Nutr 94:1088-96.