The association between blood pressure and a vegetarian diet was studied in relation to obesity, sex, age and lifestyle in 98 Seventh-day Adventist (SDA) lacto-ovo vegetarians, 82 SDA omnivores and 113 Mormon omnivores aged 25 to 44 years. Mean blood pressures adjusted for age, height and weight were significantly lower in SDA vegetarians than in Mormon omnivores (115.6/68.7 and 121.2/72.2, respectively, in males and 109.1/66.7 and 114.9/72.6, respectively, in females) and were not related to past or current use of alcohol, tobacco, tea and coffee, physical activity, personality or religious observance. Mean blood pressures in SDA omnivore males (121.7/71.7) were similar to those in Mormon males, while those in SDA omnivore females (109.9/67.4) were similar to SDA vegetarian females. Quetelet's Index in these subgroups demonstrated the same pattern as blood pressure and may reflect, in part, the high level of physical activity in female SDA omnivores. The prevalence of mild hypertension (≥ 140 mmHg systolic or ≥ 90 mmHg diastolic) was 10 and 8.5% in Mormon and SDA omnivores, respectively, compared with 1 to 2% in SDA vegetarians.
Analysis of diet records showed that vegetarians ate significantly more dietary fibre, polyunsaturated fat, magnesium and potassium and significantly less total fat, saturated fat and cholesterol than did Mormon omnivores. SDA omnivores had a dietary pattern which was less homogeneous, and which lay between those of the other groups. Which, if any, of these dietary differences were responsible for the blood pressure differences could not be determined in this study.