Scientific Update

A Review of Recent Scientific Papers Related to Vegetarianism

Note to Food Companies: Fortify Orange Juice With Vitamin D2

Vitamin D is found in fortified foods and supplements in two forms: vitamin D2 (derived from yeast) and vitamin D3 (derived from lanolin from sheep's wool). There is a question as to whether vitamin D2 is as effective as vitamin D3 in preventing vitamin D deficiency, although several recent studies indicate that both forms of vitamin D are equally effective. A new study compared vitamin D2 and vitamin D3 given as either a pill or in fortified orange juice. The study subjects were healthy 18- to 84-year-olds. They took 1,000 International Units (IU) of vitamin D in one of the forms for 11 weeks. At the end of the study, there was no significant difference in blood vitamin D levels between those who took vitamin D2 or vitamin D3, suggesting that both forms are equally effective. There was also no significant difference between those who consumed vitamin Dfortified orange juice and those who took a vitamin D supplement. Currently, orange juice is fortified with vitamin D3. This study suggests that fortification with vitamin D2 is effective and would make fortified orange juice a viable source of vitamin D for vegans.

Biancuzzo RM, Young A, Bibuld D, et al. 2010. Fortification of orange juice with vitamin D2 or vitamin D3 is as effective as an oral supplement in maintaining vitamin D status in adults. Am J Clin Nutr 91:1621-26.

Soy and School Lunch

Soy products can add variety to school lunches, provide a vegetarian option, and help to reduce the lunches' saturated fat, cholesterol, and calorie content. The school lunch program in Montgomery County, MD, the largest school food service east of the Mississippi River, conducted a trial of soy products in five middle schools. These schools were chosen to reflect the cultural diversity of the district. Four soy-based entrées were chosen to replace existing meat-based entrées. They were nuggets, a 'hybrid' patty with half ground beef and half soy, soy-based chicken-less slices on a Caesar salad, and macaroni and cheese with soy pasta. The soy-based entrées had 18 percent fewer calories, 45 percent less fat, 57 percent less saturated fat, and 20 percent less cholesterol than traditional entrées. Protein content was equivalent, fiber was six times higher in the soy-based entrées, and sodium was 20 percent higher. Different versions (soy-based and traditional) of the entrées were served on consecutive weeks. Students were not told which items were soy-based. Students selected soy-based burgers, nuggets, and pasta as often as they chose traditional products and consumed the same amounts as they did of traditional products. The chicken-less slices were not as well accepted, possibly due to appearance. This study suggests that students accept soy-based entrées and that these entrées can offer nutritional benefits.

Lazor K, Chapman N, Levine E. 2010. Soy goes to school: acceptance of healthful, vegetarian options in Maryland middle school lunches. J School Health 80:200-206.

A Walnut a Day...

People who eat four or more servings of nuts per week have, on average, a 37 percent lower risk of heart disease than those who seldom or never eat nuts. One way that nuts may help reduce the risk of heart disease is by their effects on blood cholesterol levels. Researchers at Loma Linda University combined results from 25 studies conducted in seven countries. All studies involved a comparison between subjects eating a specified amount of nuts and those not eating nuts (control group). Daily nut consumption in the study groups averaged 2.4 ounces per day. Compared with the control group, subjects in the group eating nuts had a reduction in both total and LDL-cholesterol levels. HDL-cholesterol was not affected. The effects were similar in men and women, and the type of nut did not seem to matter. Subjects eating higher amounts of nuts had a greater reduction in blood cholesterol levels than those eating lower amounts; nuts also seemed most effective in those with initially high LDL-cholesterol and in those with a low BMI. This study suggests that eating moderate amounts of nuts, along with an overall health-promoting diet, can help to lower cholesterol levels and reduce the risk of heart disease.

Sabate J, Oda K, Ros E. 2010. Nut consumption and blood lipid levels. A pooled analysis of 25 intervention trials. Arch Intern Med 170:821-27.

Vegetarians Less Likely to Be Depressed or Stressed

Some studies suggest that the omega-3 fatty acids DHA and EPA play a role in mental health and reduce the risk of depression and schizophrenia. This has potentially important implications for vegetarians whose diets contain little or no EPA or DHA. Very little research has been conducted on the mental health of vegetarians. Volunteers from Seventh-day Adventist (SDA) communities in the Phoenix, AZ, and Santa Barbara, CA, areas were surveyed and completed two psychometric tests. One test measured depression, anxiety, and stress, while the other measured mood disturbances like tension, anger, and confusion. Sixty subjects were vegetarian, and 78 were not. Scores from the psychometric tests indicated that vegetarians had an overall better mood and significantly fewer negative emotions. Vegetarians were less likely to have scores indicating depression, anxiety, or stress. Higher intakes of alpha-linolenic acid, another omega-3 fatty acid, by the vegetarians may be a partial explanation for the findings.

Beezhold BL, Johnston CS, Daigle DR. 2010. Vegetarian diets are associated with healthy mood states: a cross-sectional study in Seventh-day Adventist adults. Nutr J 9(1):26. [Epub ahead of print].

Soy Does Not Have a Feminizing Effect on Men

Every now and then, VRG gets questions about soy safety for men. Sensational stories in the popular press, often based on research in mice or rats, lead men to wonder if eating soy will lead to infertility or feminization. A recent report looks at the published research studies and concludes that exposure to soy isoflavones, in reasonable amounts, does not have a harmful effect on hormone levels (testosterone or estrogen) and does not affect sperm or semen production. In one anecdotal study where soy consumption may have led to male breast enlargement, the 60-year old subject drank three quarts of soymilk every day, an amount far above what most people use. Reports like this one may make some men avoid soy. This is unfortunate because soy foods may reduce the risk of prostate cancer and inhibit its spread (metastasis). Mark Messina, PhD, a soy expert, concludes, "Men can feel confident that making soy a part of their diet will not compromise their virility or reproductive health."

Messina M. 2010. Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence. Fertil Steril 93:2095-2104.

Choose Brown Rice

Every year, the average person in the U.S. eats approximately 20 pounds of rice—almost half a pound a week. More than 70 percent of that rice is white rice. Long ago, brown rice was the grain of choice. Then, people figured out how to remove rice's brown hull, leaving less flavorful but what some said was more aesthetically pleasing white rice. Unfortunately, white rice has lost its fiber and many vitamins and minerals. Some of the nutrients are added back when the rice is enriched, but the fiber is not replaced. This leads us to a recent study that looked at brown rice and white rice use by nearly 200,000 U.S. adults and whether rice choices affected risk of diabetes. Those who ate more than five servings of white rice a week had a higher risk of developing type 2 diabetes than did those eating less than one serving of white rice a month. In contrast, subjects eating two or more servings of brown rice a week had a lower risk of type 2 diabetes compared to those eating less than one serving of brown rice a month. These associations did not go away even when factors such as body weight, smoking, activity, and family history were adjusted for. Replacing as little as a third of a serving of white rice a day with the same amount of brown rice led, on average, to a 16 percent lower risk of type 2 diabetes. There are many possible explanations for these benefits of brown rice; it may be the higher fiber content, or the magnesium or other minerals that aren't lost in refining. In any case, if you usually eat white rice, give brown rice a try.

Sun Q, Spiegelman D, van Dam RM, et al. 2010. White rice, brown rice, and risk of type 2 diabetes in US men and women. Arch Intern Med 170(11):961-69.