Scientific Update: A REVIEW OF RECENT SCIENTIFIC PAPERS RELATED TO VEGETARIANISM
Vegans and Vegetarians at Lower Risk for Cataracts
A cataract is a clouding of the lens in the eye that leads to vision loss. Cataracts are common in older people. More than half of 80-year-olds in the United States either have a cataract or have had cataract surgery, and age-related cataracts are responsible for almost half of blindness worldwide. Vegetarians may be at lower risk of developing cataracts because their diets are higher in antioxidants like vitamins A and C and lutein, all of which have been associated with a lower risk of cataracts. British researchers studied more than 27,000 people over age 40 and found a strong relationship between diet and cataract risk. Compared to people eating more than 3 ounces of meat a day, vegans had a 40 percent lower risk of developing a cataract, vegetarians who ate dairy and/or eggs had a 30 percent reduced risk, and fish-eaters had a 20 percent lower risk. While the researchers suspect that differences in nutrients among the groups led to the differences in risk of cataracts, additional research is needed to find out which factors in a vegetarian or vegan diet reduce risk of cataracts. For more information on diet and cataracts, see www.vrg.org/journal/vj2006issue1/ vj2006issue1sciupdate.htm
Appleby PN, Allen NE, Key TJ. 2011. Diet, vegetarianism, and cataract risk. Am J Clin Nutr 93:1128-35
Vegetarian Diet Offers Benefits for Type 2 Diabetes
Type 2 diabetes, the most common kind of diabetes, affects more than 8 percent of Americans. It is the seventh leading cause of death in the United States and is a major cause of heart disease and stroke. Risk factors include obesity and physical inactivity. Since vegetarians are less likely to have type 2 diabetes than people eating a conventional diet, researchers wondered what would happen if people with type 2 diabetes switched to a vegetarian diet. To study this, 74 people with type 2 diabetes were randomly assigned to either a vegetarian diet or a conventional diabetic diet for six months. The vegetarian diet was a near-vegan diet with animal products limited to one portion of lowfat yogurt daily. Both diets provided approximately 500 fewer calories per day than the subjects were estimated to need. For the last three months of the study, subjects were placed on an individualized exercise program. More than 40 percent of subjects eating a vegetarian diet were able to reduce their diabetes medication compared to 5 percent of those eating a conventional diabetic diet. The vegetarian group lost more weight and body fat, had a greater decrease in waist circumference and LDL (bad) cholesterol, and reported a greater increase in quality of life. The results of this study suggest that vegetarian diets emphasizing beans, grains, fruits, vegetables, and nuts, along with reduced calories and increased physical activity, are helpful and should be promoted for people with type 2 diabetes. Of course, people with type 2 diabetes should consult their health care provider before making major dietary changes.
Kahleova H, Matoulek M, Malinska H, et al. 2011. Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with Type 2 diabetes. Diabet Med 28:549-59
Nutrient-Dense Vegetarian Diets Recommended for Weight Management
Studies repeatedly show that, as a group, vegetarians are less likely to be overweight than non-vegetarians. It seems logical that health care providers should be recommending vegetarian diets as one way to control weight. Some providers, however, are still concerned about the nutritional adequacy of vegetarian diets. A recent study took a unique approach to address this concern and to compare vegetarian meals to non-vegetarian meals. Researchers from Eastern Michigan University used records from the National Health and Nutrition Examination Survey (NHANES), a large study conducted by the Centers for Disease Control (CDC). Study participants who did not eat meat, poultry, or fish on the day they completed food records were categorized as vegetarian in terms of analyzing that day's diet. Compared to people eating non-vegetarian diets on the day of the survey, people eating vegetarian diets had higher intakes of fiber, calcium, iron, vitamins A and C, and other vitamins and minerals. Although protein intake was lower, it was adequate. Total fat, saturated fat, and cholesterol intakes were also lower in people eating a vegetarian diet. Vegetarian diets were closer to dietary guidelines. Those who ate a vegetarian diet on the day of the study ate twice as many whole grains and dried beans as did those eating a non-vegetarian diet. While vegetable intakes were similar, those eating a vegetarian diet ate more dark-green vegetables; those eating a non-vegetarian diet ate more potatoes. The average calorie level of a vegetarian diet was 350 calories lower than a non-vegetarian diet. If we look at the level of nutrients per calorie, it's clear that a vegetarian diet comes out ahead. These results suggest that a nutrient-dense vegetarian diet can be recommended for weight control without hesitation.
Farmer B, Larson BT, Fulgoni VL, et al. 2011. A vegetarian dietary pattern as a nutrient-dense approach to weight management: an analysis of the National Health and Nutrition Examination Survey 1999-2004. J Am Diet Assoc 111:819-27.
Vegetarian School Lunch Menus Revised
Former VRG Intern Stephanie Gall, MS, RD, and current VRG Intern Megan Salazar have revised the already vegetarian lunch menu for a private Seventh- day Adventist school in Colorado. Now, the menu includes more fresh fruits, vegetables, and whole grains and less sodium and fat. Seasonal food choices were also incorporated. In addition, the revised menus were still affordable. The results from this project have implications for any school system looking to improve their vegetarian offerings or incorporating meatless meals into the school week. You can read more about this project and see samples of the recipes used at www.vrg.org/fsupdate/index.htm
It's easy to be a school cafeteria know-it-all, until you actually see what happens in a school cafeteria. Coach Ryan Andrews, MS, RD, learned 18 lessons during his one-year stint as a school cafeteria worker: www.precisionnutrition.com/lunch-lady-ryan
Possible Link Between Poor Diet and Mental Health Issues in Early Adolescence
Research suggests that nearly 50 percent of all lifelong mental health disorders appear by age 14. This is the approximate age when adolescents establish lifestyle behaviors, such as diet, physical activity, and risk-taking behavior. These behaviors, as well as demographic factors such as gender and family income, may be associated with children's mental health. Studies have shown that a Western diet, which typically features a high intake of red meat, sugar, and fast foods, may be linked to mental health disorders, such as depression and attention deficit hyperactivity disorder (ADHD).
One study aimed to identify specific factors correlated with mental health problems in early adolescence. Researchers interviewed 1,598 participants from the Western Australian Pregnancy Cohort (Raine) Study, when the subjects were 14 years old. Each adolescent's primary caregiver completed questionnaires covering socio-demographic and family information, the child's behavior, and the subject’s diet over the previous year. They were asked to describe the diet in terms of number of servings according to Australian dietary recommendations. Also, the adolescents completed a separate questionnaire about their activities and risk-taking behaviors.
At least 14 percent of the adolescents studied showed signs of mental health abnormalities. Those who had a higher intake of meat, meat alternatives, and 'junk' food were also more likely to have poorer mental health. One partial explanation for this may be that 'junk' food, such as high-fat, low-nutrient snacks and fast food, is typically low in important micronutrients that are essential for healthy brain function. In addition, higher ‘junk’ food consumption may be linked to other factors that are associated with poor mental health, such as lower family income and high television viewership. A greater focus on establishing healthful lifestyle behaviors, including limiting the amounts of snack foods and meats in adolescent diets, may help to promote better mental health.
Robinson M, Kendall GE, Jacoby P, et al. 2010. Lifestyle and demographic correlates of poor mental health in early adolescence. J Paediatr Child Health 47:54-61.
*Written by Rita Pruzansky, psychology student and VRG volunteer