When former president Bill Clinton adopted a (mostly) vegan diet, people began to take notice of a lifestyle once considered alternative or extreme. Veganism is gaining interest among the public and nutrition researchers. While concerns for animal and environmental rights still inspire many to adopt veganism, the diet’s move into the mainstream also is supported by mounting recognition of the benefits of plant-based menus for reducing blood cholesterol levels and potentially warding off heart disease.
Vegans continue to make up only a small percentage of Western populations; approximately two to three percent of the U.S. population identifies as vegan. These small numbers present a challenge in assessing disease rates. Furthermore, in some studies where vegetarians are found to be at lower risk for heart disease, vegans and lacto-ovo vegetarians are grouped together. In a recent analysis of the Adventist Health Study-2, however, vegan men (but not vegan women) had a lower risk of dying from heart disease compared to lacto-ovo-vegetarians and non-vegetarians.
But while data are lacking on heart disease rates, both dietary habits and markers of disease risk among vegans suggest that this way of eating protects against heart disease. Vegan diets are cholesterol-free, and typically low in saturated fat compared to both omnivore and lacto-ovo vegetarian diets. The higher ratio of polyunsaturated fat to saturated fat in their diets helps explain why vegans generally have lower blood levels of LDL-cholesterol. And despite their higher carbohydrate intake, vegans also often have lower levels of triglycerides.
Both the EPIC-Oxford and the Adventist Health Study-2 have found considerably lower rates of hypertension among vegans. Lower body mass index is part of the reason for this, but the complete explanation remains unclear. Here’s what we do know about the vegan diet and heart health:
- Vegans usually have higher fiber intakes than omnivores. Soluble fiber in particular may act in a number of ways to reduce blood cholesterol levels.
- Vegans also may consume more soy products than most meat-eaters. Soy protein has a direct cholesterol-lowering effect. Isoflavones found in soy products may also reduce CHD risk by improving the health of the arteries.
- In contrast to those protective effects, vegans who don’t supplement with vitamin B12 may have high blood levels of an amino acid called homocysteine, which can raise heart disease risk.
- Vegans also have lower plasma levels of the long chain omega-3 fatty acid, DHA, although the significance of this for heart disease isn’t known. Inadequate intakes of either vitamin B12 or DHA are easily resolved with supplements.
Most of the available evidence on vegan diets and biomarkers suggests that vegan diets should be beneficial in lowering risk for the development of heart disease. In addition, there is evidence that they can be useful in the treatment of this disease. In 1990, Dr. Dean Ornish and colleagues from the California Pacific Medical Center studied a mostly vegan diet (participants consumed one to two servings of low-fat dairy or egg whites per day) as part of a comprehensive lifestyle program that also included exercise, stress management and social support. Subjects in the control group were not asked to make any lifestyle changes. After one year, 82 percent of patients in the treatment group experienced regression of coronary artery lesions whereas a majority of patients in the usual care group experienced lesion progression. Diet was only one component of the program making it difficult to determine its overall contribution to the improvements.
Researchers from the University of Toronto tested a different type of vegan diet, one much higher in fat, in overweight individuals with elevated cholesterol. In this small, four-week trial, half of the study participants consumed a vegan diet that was 43 percent fat and 31 percent protein compared to a 25 percent fat lacto-ovo vegetarian diet. At the end of four weeks, both groups experienced weight loss and reductions in LDL-cholesterol levels, but improvements in lipid levels were greater in the group following the high-fat vegan diet. However, the vegan diet was also more than 30 percent higher in fiber, which may explain much of the difference in lipid levels.
As research interest in plant-based diets continues to grow, more information on disease rates in vegans will hopefully become available. What is clear is that typical vegan diets incorporate many elements of heart-healthy eating and vegans consistently have fewer risk factors for heart disease. Limited evidence also suggests that a vegan diet is a useful approach for treating atherosclerosis and reversing risk factors for heart disease.