Nutritional factors and blood pressure control: an assessment.

Abstract

High blood pressure is a concern because of its associated risks. Hypertension, therefore, is best defined as the level of blood pressure at or above which treatment can be expected to do more good than harm. Blood pressure is subject to multiple systems of feedback control; essential hypertension can result from multiple causes. The heterogeneity of essential hypertension may explain some of the apparent contradictions in existing data, including the disparity between the consistency of the association of sodium intake with blood pressure among various population groups versus the lack of this correlation among persons within a given population. A more sophisticated approach toward statistical modeling is needed. Nutrients, foods, and diet are separate, although interrelated, concepts. Failure to distinguish among these terms has contributed to our current confusion. Consequences of this distinction include difficulty in altering intakes of single nutrients without altering those of other nutrients within the overall diet. Public health efforts should be directed toward changes in nutrient intake rather than toward simplistic and misleading classifications of foods as being "good" or "bad." Scientific and public policy activities can be divided into four categories—original research, expert analysis, formulation of public health policy, and implementation of overall public policy—each with its own appropriate rules and limitations. In regard to dietary factors and blood pressure control, the data on sodium, potassium, alcohol, and body weight are abundant (although not sufficient); data regarding calcium, magnesium, and dietary fats must still be considered preliminary; and data on dietary carbohydrates, fiber, and trace elements are insufficient to warrant further analysis. A panel of experts, chosen to represent the legitimate range of scientific opinion, should assess the strength and consistency of the evidence relating dietary factors to blood pressure control (where data exist) according to one of several schemes for classifying types of studies. Meanwhile, further research, dissemination of credible information, and, in a few circumstances, active programs of education and behavioral intervention would seem warranted with regard to dietary sodium and potassium, alcohol intake, and obesity. Other than voluntary labeling, there currently seems to be little need for more formal regulatory measures. Instead, the attention of the scientific community should be directed toward providing better data and more useful expert analysis, so that public health policy and overall public policy can be founded on as rational a data base as possible.