24 Feb Vegetarian Diet and Blood Pressure Lowering Effect
MedicalResearch.com Interview with:
Yoko Yokoyama, Ph.D., M.P.H.
National Cerebral and Cardiovascular Center, Osaka, Japan,
MedicalResearch.com: What are the main findings of the study?
Dr. Yokoyama: We found consistent evidence that a vegetarian diet has a significant blood-pressure-lowering effect, and this was clear both in observational studies of individuals who had chosen vegetarian diets on their own and in intervention trials in which people were asked to make diet changes.
Our meta-analysis included 32 observational studies and 7 controlled clinical trials. In the observational studies, vegetarian diets were associated with blood pressures that were about 7 mmHg lower systolic and 5 mmHg lower diastolic. In the clinical trials, the reductions were about 5 mmHg systolic and 2 mmHg diastolic. These are pooled averages, so for some individuals, particularly those with higher body weights or higher blood pressures at the beginning, the blood-pressure-lowering effects could be much greater.
MedicalResearch.com: Were any of the findings unexpected?
Dr. Yokoyama: Vegetarian diets have long been known to lower blood pressure. In fact, the DASH (Dietary Approaches to Stop Hypertension) study was inspired by exactly this observation. What is new is the consistency of this finding and our ability to quantify it. It is a clinically very important finding, because a drop of just 5 mmHg BP would be expected to result in a 9% reduction of mortality due to coronary heart disease and 14% for stroke. This change is approximately half the magnitude of pharmaceutical therapy.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Yokoyama: These findings establish the value of nonpharmacologic means for reducing BP. Unlike drugs, there is no cost to a diet adjustment of this type, and all the “side effects” of a plant-based diet are desirable: weight loss, lower cholesterol, and better blood sugar control, among others.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
- Studies to clarify which types of vegetarian diets are most strongly associated with lower BP. One might hypothesize that a vegan diet would be most effective because of the absence of dairy products, which are a major source of saturated fat, which is believed to have a negative effect on blood viscosity and, in turn, blood pressure. But that is yet to be shown.
- Studies to clarify mechanisms how vegetarian diets could change health outcomes such as hypertension. Aside from effects on blood viscosity, the diet boosts potassium intake, among other factors.
- We would like to see more studies on the best ways of assisting people in adopting plant-based diets. Because they don’t require limitations on calories, carbohydrates, etc., these diets are very attractive, and deserve more study.