A recent study offers evidence for people with high blood pressure to “Go Veggie”. It has been well known that high blood pressure is a risk factor for diseases like heart disease. Lifestyle factors, like diet and exercise, contribute to controlling blood pressure and avoiding heart disease. Researchers from the Japan and the Physicians Committee for Responsible Medicine in Washington suggest that a vegetarian diet could be an alternative for people with high blood pressure, rather than taking drugs.
Researchers in Osaka, Japan performed a meta-analysis of existing studies investigating the relationship between vegetarian diets and blood pressure to clarify the issue of conflicting results from other studies. “Vegetarian diets” were defined as excluding or rarely eating meat, but including dairy products, eggs, and fish.
Published in the journal JAMA Internal Medicine, the researchers analyzed the findings of seven clinical trials (totaling 311 participants) and 32 observational studies (21,604 participants in total). They measured the difference in blood pressure between participants who followed a vegetarian diet and participants who followed an omnivorous diet – individuals who eat both meat and vegetables.
Blood pressure is typically articulated in terms of the systolic pressure - the pressure in the arteries when the heart beats- over diastolic pressure -the pressure in the arteries between heartbeats- and is measured in millimeters of mercury (mm Hg). A reading of 120mm Hg/80mm Hg or less is considered normal for most people.
The researchers found that the diastolic pressure was 2.2mm Hg lower in clinical trials and 4.7 mm Hg lower in observational studies for individuals who are following a vegetarian diet. The researchers believe this reduction is equivalent to health benefits of a low-sodium diet or weight reduction of 11 pounds.
A systolic blood pressure reduction of five mm Hg is also associated with a nine percent lower risk of death from coronary heart disease and 14 percent lower risk of death from stroke.
Vegetarians generally have a lower body mass index and are at lower risk of obesity than omnivores. The researchers are considering that since body weight and blood pressure are linked, this might explain the lowered blood pressure in vegetarians.
Another theory is that vegetarian diets are high in potassium and low in sodium, but some studies have disagreed over the impact. Also, vegetarian diets are usually proportionally lower than omnivorous diets in saturated fatty acids and higher in polyunsaturated fatty acids - qualities associated with lower blood pressure.
The researchers released a statement, “Further studies are needed to explore the relationships between specific foods and nutrients and blood pressure. Nevertheless, the results of the meta-analysis of the controlled trials suggest a robust relationship between consumption of vegetarian diets and lower blood pressure.”
Yokoyama, Y., Nishimura, K., Barnard, N. D., Takegami, M., Watanabe, M., Sekikawa, A., ... & Miyamoto, Y. (2014). Vegetarian diets and blood pressure: a meta-analysis. JAMA internal medicine, 174(4), 577-587.