What is the impact of vegetarian diets on heart disease?

Vegetarian diets improve all diet-related tradition heart disease risk factors, including cholesterol profile, blood pressure, blood glucose, and diet quality. The effect of vegetarian diets on these risk factors illustrates a study in which community dwelling individuals participated in a program called CHIP (Coronary Health Improvement Project). In addition to adopting a vegetarian diet for four weeks, participants were recommended to engage in about 30 minutes per day of moderate intensity physical activity. Among participants, about 70 percent weighed more than 10 percent above their ideal body weight, 14 percent had diabetes, 47 had hypertension and 32 had coronary heart disease.

Cholesterol levels were reduced among all participants. Among participants with a total cholesterol above 279 mg/dl prior to the study (with the average cholesterol of 303 mg/dl among men), a 33 percent reduction was observed to a level of 203 mg/dl. Among women, a 14 percent reduction was observed (from 306 mg/dl to 261 mg/dl). The so-called bad cholesterol (LDL-cholesterol) was reduced among men on average from 210 mg/dl to 138 mg/dl, or by 34 percent, whereas among women the reduction was 19 percent (from 210 mg/dl to 177 mg/dl). Additional benefits were noted among study participants. For example, blood pressure was reduced, blood sugar level was improved and reduction in body weight was reported. All of these results occurred after just 4 weeks on the CHIP program. The author of the study and developer of the CHIP program stated as follow: “Often, participants were able to decrease or discontinue antidiabetic, hypolipidemic, and antihypertensive medication. Reductions in important markers of coronary risk, such as serum lipid levels, were significant and rapid.” The table below includes the pre- and post-CHIP intervention data.

The improved profile of heart disease translates to a reduced risk of heart attack and other heart and vascular health condition. The following quote summarizes results of one study known as the EPIC-Oxford study from Great Britain, that illustrate this effect. “Vegetarians had a 32% lower risk (HR: 0.68; 95% CI: 0.58, 0.81) of IHD than did nonvegetarians, which was only slightly attenuated after adjustment for BMI and did not differ materially by sex, age, BMI, smoking, or the presence of IHD risk factors.”

In addition to being associated with heart disease prevention, vegetarian diets have been consistently shown in different studies to reverse atherosclerosis, the underlying cause of most heart and cardiovascular health problems. For example, in the first study that documented such effect, Dr. Ornish assigned 28 individuals between 35 and 75 years old who had coronary heart disease documented by angiography to follow a low-fat vegetarian diet, underwent a stress management seminar, and were engaged in moderate physical activity. The Atherosclerotic lesions in coronary arteries of these individuals were reduced from 40.0 to 37.8 percent after just one year of treatment. Among patients with initial deposits of 50.0 percent or higher, a reduction on average from 61.1 to 55.8 percent was noticed. Among people who did not make dietary or other lifestyle modifications included in this study, cholesterol deposits increased on average from 42.7 to 46.1 percent. Among those with initial size of these deposits higher than 50 percent, they increased from 61.7 to 64.4 percent. The results were summarized as follow: “Comprehensive lifestyle changes may be able to bring about regression of even severe coronary atherosclerosis after only 1 year, without use of lipid-lowering drugs.”