The evidence that vegetarians have lower blood pressures than non-vegetarians is impressive. This is even true if the non-vegetarian group consist of non-smokers, though abstinence from alcohol may also help to keep the blood pressures of vegetarians lower than that of non-vegetarians.56 The increase in blood pressure with age is also significantly less in vegetarians than in non-vegetarians. Furthermore, blood pressures of vegan vegetarians are slightly lower than those of ovo-lacto vegetarians, being some 5-8mm Hg lower in the vegans.57 When 250 g/day of lean beef was fed to 21 strict vegetarians it was found that systolic blood pressure increased significantly by the third week, but diastolic blood pressure was not significantly affected. Furthermore, plasma cholesterol levels rose by 19% during the meat period but returned to normal after ten days on the vegetarian diet.57 It has been shown that increase in blood pressure cannot be attributed to the presence of meat protein, so some other factor must be responsible for the observed blood pressures of vegetarians.58 Considering that even a small reduction in systolic blood pressure (5 mm Hg) can substantially reduce the number of major coronary events, it is not surprising that vegetarians are less likely to suffer heart attacks, resulting from cardiovascular disease, than their omnivorous counterparts.37,59 In figure 5.6 a typical blood pressure profile of vegetarians and non-vegetarians is shown.
Figure 5.6. Blood pressure in vegetarians (squares) and omnivores (dots). Results of systolic and diastolic pressures for men are shown on the left and those for women on the right. Adapted from reference 59).