Researchers from Japan recently published a meta-analysis of clinical trials and cross-sectional observational studies of a vegetarian diet and blood pressure (BP) (42). Many of these vegetarians were semi-vegetarians.
Among seven clinical trials, a vegetarian diet was found to reduce systolic and diastolic blood pressure by an average of 4.8 and 2.2 mm Hg, respectively. Among the 32 cross-sectional studies, vegetarians were found to have a lower systolic and diastolic blood pressure of 6.9 and 4.7 mm Hg respectively. These findings were statistically significant.
The authors said, “According to Whelton et al, a reduction in systolic BP of 5 mm Hg would be expected to result in a 7%, 9%, and 14% overall reduction in mortality due to all causes, coronary heart disease, and stroke, respectively….Obesity, excessive sodium intake, and excessive alcohol use are associated with increased BP and risk of hypertension; potassium intake and physical activity are associated with lower BP. In addition, intake of unsaturated fat, protein, magnesium, and dietary fiber may be associated with differences in BP.”
Interestingly, the only clinical trial that showed a vegetarian diet to increase blood pressure was the first PCRM pilot study using a vegan diet to treat type 2 diabetes (2). Diastolic blood pressure did decrease more in the control group, than the vegan group, in that study, while those on the vegan diet ended up with lower systolic blood pressure. However, two of the five subjects on the vegan diet who were on blood pressure medication discontinued their medication, while only one of four in the control group discontinued.
I have updated the Blood Pressure section of Disease Markers of Vegetarians
1. Yokoyama Y, Nishimura K, Barnard ND, Takegami M, Watanabe M, Sekikawa A, Okamura T, Miyamoto Y. Vegetarian Diets and Blood Pressure: A Meta-analysis. JAMA Intern Med. 2014 Feb 24. | link
2. Nicholson AS, Sklar M, Barnard ND, Gore S, Sullivan R, Browning S. Toward improved management of NIDDM: A randomized, controlled, pilot intervention using a lowfat, vegetarian diet. Prev Med. 1999 Aug;29(2):87-91. | link