Scientific Update
By Reed Mangels, PhD, RD, FADA
New Dietary Guidelines for Americans Endorse a "Healthy Vegetarian Eating Pattern"
Dietary Guidelines for Americans is a statement of current federal policy on the role of dietary factors in health promotion and disease prevention. The USDA and the Department of Health and Human Services issue Dietary Guidelines every five years. The latest was released in January 2016 and endorsed "a healthy vegetarian eating pattern" as one of three "healthy eating patterns that can be adapted based on cultural and personal preferences. The USDA Food Patterns [including the healthy vegetarian pattern] can be used as guides to plan and serve meals not only for the individual and household but in a variety of other settings, including schools, worksites, and other community settings."
A "Healthy Vegetarian Eating Pattern," as described by the Dietary Guidelines, includes vegetables, fruits, grains, dairy or fortified soymilk (or other plant-based dairy substitutes), legumes including soy products, nuts and seeds. The eating pattern was developed based on foods and amounts of foods eaten by self-described vegetarians in the United States based on a large national study. The "Healthy Vegetarian Eating Pattern" is described as "similar in meeting nutrient standards to the Healthy U.S.-Style Pattern, but somewhat higher in calcium and fiber and lower in vitamin D due to differences in the foods included."
To see details of the Healthy Vegetarian Eating Pattern, go to http://health.gov/dietaryguidelines/2015/guidelines/appendix-5/
U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015 - 2020 Dietary Guidelines for Americans. 8th Edition. December 2015. Available at http://health.gov/dietaryguidelines/2015/guidelines/.
Mortality in Vegetarians
Many studies have shown that vegetarians (including vegans) are less likely to get some chronic diseases such as heart disease, some kinds of cancer, diabetes, and obesity. Does this lower disease risk also mean that vegetarians will live longer? Research on Seventh-day Adventists in the United States and Canada found that the group the researchers called "vegans" (consumed any animal product less than once a month) as well as "lacto-ovo vegetarians" (consumed eggs or dairy at least once a month, other animal products less than once a month), and "pesco-vegetarians" (fish at least once a month, meat less than once a month) had a lower risk of death than did non-vegetarians1.
A recently-published study of vegetarians in the United Kingdom had somewhat different results. This study of more than 60,000 people, about a third of whom were vegetarian, reported no significant difference in risk of death overall between meat eaters, vegetarians, or vegans. Subjects began the study as early as 1980 and were studied until 2014 or their death. Vegetarians in this study were defined as not eating meat or fish; vegans did not eat meat, fish, eggs, or dairy products. Compared to the group that ate meat regularly, vegetarians and vegans were much less likely to die from pancreatic cancer or lymphomas or similar cancers. When only participants who had not changed their diets during the study period and who died before age 75 were examined, vegetarians and vegans had a slightly lower risk of death2.
The finding that vegetarians and vegans had a lower risk of death before age 75 but not before age 90 suggests that at some point, medical intervention can prolong life even in someone who has significant heart disease. A question that these studies did not address was the quality of life, which may be more important than the length of one's life. Both studies suggest that there is no disadvantage to being vegetarian or vegan in terms of risk of death.
1 Orlich MJ, Singh PN, Sabaté J, et al. 2013. Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Intern Med. 173:1230-8.
2 Appleby PN, Crowe FL, Bradbury KE, Travis RC, Key TJ. 2016. Mortality in vegetarians and comparable nonvegetarians in the United Kingdom. Am J ClinNutr. 103:218-30.
A Cautionary Tale
If you look on The Vegetarian Resource Group's website, you'll see the statement, "Soymilk, rice milk, other plant milks, and homemade formulas, should not be used to replace breast milk or commercial infant formula during the first year." A recently-published case study lends support to this statement. The study reported that when a Spanish infant was 2 1/2 months old, his parents stopped giving him infant formula because he had a rash, and replaced the formula with almond milk. From age 2 1/2 months to 11 months, the baby drank almond milk. Although the infant's parents tried to feed him puréed fruits and vegetables when he was 6 months old, he wouldn't eat them. At 11 months, the baby was diagnosed with deficiencies of vitamin C, vitamin D, and zinc and was found to have broken bones in his legs and spine due to these deficiencies. He was given an infant formula and started on age appropriate foods and recovered from his early malnutrition. Ironically, a medical doctor originally suggested that the infant be given almond milk, which led to the infant's health problems as the almond milk was clearly not adequate for his needs. As this study's authors state, "Pediatricians and parents should be aware that plant based beverages are not a complete food and they may not replace breastfeeding or infant formula."
Vitoria I, López B, Gómez J, et al. 2016. Improper use of a plant-based vitamin C-deficient beverage causes scurvy in an infant. Pediatrics. 137:1-5.
Health Benefits of Nuts
Several years ago, we reported that people who eat four or more servings of nuts a week have a markedly lower risk of heart disease, compared to those who seldom or never eat nuts. A recent study provided an update on health benefits of nuts. Researchers at Tufts University conducted a type of study called a meta-analysis that combined the results of 61 studies in which some subjects were given a specific amount of tree nuts daily (walnuts, almonds, pistachios, macadamia nuts, pecans, cashews, hazelnuts, or Brazil nuts) and some subjects did not eat nuts. They examined the effects of eating/not eating nuts on blood cholesterol, triglycerides, and HDL and LDL cholesterol and blood pressure. Typically, subjects who were assigned to the group eating nuts ate two ounces of nuts daily and the study lasted for a month. Compared with the group eating no nuts, subjects in the group eating nuts had a reduction in both total and LDL-cholesterol. HDL-cholesterol was not affected, nor was blood pressure. The type of nut eaten did not affect results. The researchers estimated that eating an ounce of nuts daily could reduce the risk of having a heart attack or stroke by 4-6 percent.
Del Gobbo LC, Falk MC, Feldman R, Lewis K, Mozaffarian D. 2015. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis, and dose-response of 61 controlled intervention trials. Am J Clin Nutr. 102:1347-56.
Iron Absorption is Affected by Being Overweight
A recent study raises questions about iron absorption in overweight and obese women and may have implications for some vegetarians. Researchers have noticed that obese people are more likely to be iron deficient. This isn't because their diets lack iron, but because they don't absorb iron very well, possibly because of the subclinical inflammation that goes along with obesity.
The iron found in plant foods is called non-heme iron, which is a comforting name, meaning that it is not produced from blood components. This form of iron is better absorbed if eaten with a good source of vitamin C such as citrus fruits, broccoli, or tomatoes. For example, the iron in dried beans is better absorbed if the beans are cooked in a tomato-based sauce.
A new study suggests that, in addition to not being able to absorb iron as well, overweight and obese women also don't get as much of a beneficial effect from vitamin C. Unlike women in the normal weight category, overweight or obese women absorbed about 1/3 less non-heme iron in a meal that didn't contain vitamin C. The increase in iron absorption when the meal contained vitamin C was only about half as high in overweight and obese women. Since women prior to menopause have high iron requirements, this worsening of absorption is concerning. In vegetarians, who rely on vitamin C to increase iron absorption from plant-based foods, it's especially concerning. If you're vegetarian or vegan, a premenopausal woman, and your BMI puts you in the overweight or obese range, consider having your iron status checked regularly.
Cepeda-Lopez AC, Melse-Boonstra A, Zimmermann MB, Herter-Aeberli I. 2015. In overweight and obese women, dietary iron absorption is reduced and the enhancement of iron absorption by ascorbic acid is one-half that in normal-weight women. Am J Clin Nutr. 102:1389-97.
