Relation of body mass and alcohol, nutrient, fiber, and caffeine intakes to blood pressure in the special intervention and usual care groups in the Multiple Risk Factor Intervention Trial

This chapter presents analyses of relations of dietary variables to blood pressure, systolic (SEP) and diastolic (DBP), for men in the special intervention (SI) and usual care (UC) groups in the Multiple Risk Factor Intervention Trial. For each dietary factor, analyses were done at baseline, for trial years 1-6, and for change from baseline to years 1-6. Analyses were done for all participants and for men receiving or not receiving antihypertensive drug treatment and were controlled for age, race, education, serum cholesterol, smoking, special diet status, and (for specific nutrients) body mass index and alcohol intake. Nutrient data for trial years 1-6, which are based on four or five dietary recalls per man, are more reliable than the baseline or change data, which are based on only one recall. Therefore, this summary focuses on data for trial years 1-6, for SI and UC men pooled. Regression analyses confirmed direct independent relations of body mass index, alcohol intake, sodium, and ratio of sodium to potassium to SEP and DBP, and an inverse relation of potassium to SEP and DBP. Dietary starch was directly related to SEP and DBP; dietary saturated fatty acid and cholesterol and Keys score were directly related to DBP; dietary magnesium, fiber, and caffeine were inversely related to SEP and DBP; and dietary protein, polyunsaturated fatty acids, the ratio of polyunsaturated to saturated fatty acid, and other simple carbohydrates were inversely related to DBP. Method problems, all tending to produce underestimations, are also reviewed.