Objective.-To test the short-term feasibility and efficacy of seven nonpharmacologic interventions in persons with high normal diastolic blood pressure.Design.-Randomized control multicenter trials.Setting.-Volunteers recruited from the community, treated and followed up at special clinics.Participants.-Of 16 821 screenees, 2182 men and women, aged 30 through 54 years, with diastolic blood pressure from 80 through 89 mm Hg were selected. Of these, 50 did not return for follow-up blood pressure measurements.Interventions.-Three life-style change groups (weight reduction, sodium reduction, and stress management) were each compared with unmasked nonintervention controls over 18 months. Four nutritional supplement groups (calcium, magnesium, potassium, and fish oil) were each compared singly, in double-blind fashion, with placebo controls over 6 months.Main Outcome Measures.-Primary: change in diastolic blood pressure from baseline to final follow-up, measured by blinded observers. Secondary: changes in systolic blood pressure and intervention compliance measures.Results.-Weight reduction intervention produced weight loss of 3.9 kg (P < .01), diastolic blood pressure change of - 2.3 mm Hg (P < .01), and systolic blood pressure change of -2.9 mmHg (P < .01). Sodium reduction interventions lowered urinary sodium excretion by 44 mmol/24 h (P < .01), diastolic blood pressure by 0.9 mm Hg (P < .05), and systolic blood pressure by 1.7 mm Hg (P < .01). Despite good compliance, neither stress management nor nutritional supplements reduced diastolic blood pressure or systolic blood pressure significantly (P > .05).Conclusions.-Weight reduction is the most effective of the strategies tested for reducing blood pressure in normotensive persons. Sodium reduction is also effective. The long-term effects of weight reduction and sodium reduction, alone and in combination, require further evaluation.

Epidemiology is the simplest and most direct method of studying the causes of disease in humans, and many major contributions have been made by studies that have demanded nothing more than the ability to count, to think logically, and to have an imaginative idea. With the accumulation of knowledge, however, its has become harder for individuals working alone to make effective contributions, and epidemiological research is becoming increasingly a matter of teamwork, not only because of the large number of people that may have to be studied and the large amount of data that have to be collected and analyzed, but also because of the need to bring together for the design and conduct of the study clinical experience, biological understanding, statistical expertise, and many other special skills that vary from one study to another. But if, in this sense, epidemiological research is becoming more complex, the core of the subject remains essentially simple, and a good epidemiological study should be capable of description in such a way that all who are interested in the cause of disease can follow the argument and decide for themselves the validity of the conclusions.