Scientific Update
A Review of Recent Scientific Papers Related to Vegetarianism
Fast Food Confidential
During a recent study, researchers collected 480 samples of hamburgers and chicken sandwiches from Burger King, McDonald's, and Wendy's in three locations in six cities. The samples were tested using a method that shows what the animals used to produce these items had been fed. The researchers had been told by the suppliers of meat to the fast food chains that they used "local farms" that fed "mixed grains." In contrast, all of the chicken and 93 percent of the beef examined came from animals that had been fed an exclusively corn-based diet. This suggests that the animals had been fed corn, rather than grass or other grains, to rapidly fatten them up prior to slaughter. In addition, relatively high levels of a form of nitrogen found in samples was said to indicate that the animals had been confined rather than outdoors. While this may not be news to vegetarians, researchers hope that their findings will spark consumers' curiosity about the origins of their food.
Jahren AH, Kraft RA. 2008. Carbon and nitrogen stable isotopes in fast food: Signatures of corn and confinement. Proc Nat Acad Sci 105:17,855-60.
Gluten-Free Vegan Diet May Lower Bad Cholesterol and Reduce Inflammation in People with Rheumatoid Arthritis
Rheumatoid arthritis affects more than 1.3 million adults in the U.S. It is an autoimmune disease, which means that the symptoms are due to a person's immune system attacking his or her own body. Besides joint pain, people with rheumatoid arthritis are also at increased risk for heart disease. Swedish researchers studied 66 people with rheumatoid arthritis. Thirty-eight of them were randomly assigned to follow a gluten-free vegan diet for a year, while 28 were assigned to what the investigators called a "well-balanced non-vegan diet." The gluten-free diet was based on corn, rice, millet, buckwheat, and sunflower seeds; it did not contain wheat and other sources of gluten. Thirty subjects on the vegan diet and 28 on the non-vegan diet completed at least three months of the study and were included in the analyses. The group on the vegan diet lost significantly more weight and had reduced levels of LDL (bad) cholesterol. They also had lower levels of an indicator of inflammation. This study was quite small, so additional research is necessary to corroborate these results.
Elkan A-C, Sjoberg B, Kolsrud B, et al. Gluten-free vegan diet induces decreased LDL and oxidized LDL levels and raised atheroprotective natural antibodies against phosphorylcholine in patients with rheumatoid arthritis: a randomized study. Arthritis Ther 10(2):R34. Epub 2008 Mar 18.
Dietary Improvements Seen in People with Type 2 Diabetes Following a Lowfat Vegan Diet
Type 2 diabetes affects close to 11 percent of U.S. adults and costs $174 billion a year in medical costs alone. A lowfat vegan diet has been shown to be part of an effective treatment for type 2 diabetes (www.vrg.org/ journal/vj2007issue1/vj2007issue1.pdf). A recent study looked at dietary changes made by participants following a lowfat vegan diet to treat type 2 diabetes. Ninety-nine men and women with type 2 diabetes were assigned to either a lowfat vegan diet or a standard diabetes diet and then studied for 22 weeks. The group eating the vegan diet reported higher intakes of carbohydrate, fiber, beta-carotene, and vitamin C compared to their pre-study diet. The other group had lower intakes of iron; this was not the case for the vegan group. Both groups had difficulty meeting recommendations for vitamins D and E, calcium, and potassium and consumed too much sodium. The vegan group increased their intake of vegetables, fruits, nuts, and soy protein, while the other group increased their intake of soy protein and nuts. Both groups decreased their intake of harmful trans fats. These results suggest that a lowfat vegan diet can lead to a healthier overall diet in people with type 2 diabetes. Of course, people with diabetes should consult with their health care provider before making marked dietary changes.
Turner-McGrievy G, Barnard ND, Cohen J, et al. 2008. Changes in nutrient intake and dietary quality among participants with type 2 diabetes following a low-fat vegan diet or a conventional diabetes diet for 22 weeks. J Am Diet Assoc 108:1636-45.
High-Fat Dairy Products and Eggs Associated with Increased Risk of Heart Failure
Ever wonder what the heart does? It's actually a pump that moves blood throughout our bodies. What happens if your heart isn't working properly? Heart failure is when the heart can't pump enough blood, leading to a back-up of blood and fluid in the lungs, swelling (edema), tiredness, and shortness of breath. Heart failure is a serious condition and is associated with 300,000 deaths a year in the United States. High cholesterol levels, high blood pressure, and diabetes all increase risk for heart failure. A large study of subjects in Mississippi, North Carolina, Minnesota, and Maryland recently reported on dietary factors that increase risk of developing heart failure. More than 14,000 people were studied. People who had heart failure were more likely to have a higher intake of high-fat dairy products and eggs. Higher intakes of whole-grain foods were associated with a lower risk of heart failure. If you're concerned about heart failure, it seems prudent to reduce or avoid eggs and high-fat dairy products and to eat more whole grains.
Nettleton JA, Steffen LM, Loehr LR, et al. 2008. Incident heart failure is associated with lower whole-grain intake and greater high-fat dairy and egg intake in the Atherosclerosis Risk in Communities (ARIC) Study. J Am Diet Assoc 108:1881-87.
Vegetarian Diet May Reduce Oxidative Damage Associated With Aging
Antioxidants such as vitamin C, beta-carotene, and vitamin E are believed to protect cells in our body from damage by free radicals. Free radicals can be produced following exposure to cigarette smoke, pollution, radiation, and other harmful substances and may play a role in the development of cancer, heart disease, and other health problems, as well as aging. Vegetarian diets would be expected to contain generous amounts of antioxidants, which are frequently found in fruits and vegetables. Do vegetarians actually have less damage due to free radicals (oxidative damage)? A study conducted in the Slovak Republic examined this question. Four groups were examined: young lacto-ovo vegetarian women, young non-vegetarian women, older lacto-ovo vegetarian women, and older non-vegetarian women. Young women were 20-30 years old; older women were 60-70 years old. The older vegetarians had significantly less evidence of DNA breaks, suggesting less oxidative damage compared to the older non-vegetarians. This may have been due to higher blood levels of vitamin C and beta-carotene in the vegetarians' diets. No differences were seen in the younger women; both groups had results similar to those of the vegetarian women. These results suggest that a vegetarian diet with generous amounts of fruits and vegetables can reduce the amount of oxidative damage commonly seen with aging.
Krajcovicova-Kudlackova M, Valachovikova M, Paukova V, et al. 2008. Effects of diet and age on oxidative damage products in healthy subjects. Physiol Res 57:647-51.
How Quickly Did You Eat Your Lunch Today?
Does eating quickly have any relation to weight? As you may have guessed, it seems to. Japanese researchers studied more than 4,000 adults and asked the research subjects if they would describe their typical eating speed as very slow, slow, medium, or fast and if they usually ate until they felt full. They also measured the subjects' height and weight. Nearly 46 percent of men and 36 percent of women said that they ate quickly. Approximately 50 percent of the men studied and 58 percent of the women reported eating until they felt full. Subjects who reported that they ate quickly and those reporting eating until they felt full were heavier and had a higher BMI than other subjects. Those who both ate quickly and ate until they felt full had an even higher risk of being overweight than did those who only had one of these behaviors. If you eat very quickly, try slowing down a bit. You'll feel better, and you might reduce your risk of becoming overweight as well.
Maruyama K, Sato S, Chira T, et al. 2008 Oct 21. The joint impact on being overweight of self reported behaviours of eating quickly and eating until full: cross sectional survey. BMJ 337:a2002.
