Reduction of dietary sodium in Western Society. Benefit or risk?

T HERE is widespread interest in relationships between dietary electrolyte intake and arterial pressure. Attention has been directed to potassium, calcium, and magnesium, but the predominant discussion has been of the possible role of dietary sodium in determining the level of blood pressure in Western society. Experts viewing information from animal research, from intra-and interpopulation studies, and from manipulations of sodium intake in hypertensive and normotensive individuals have joined two opposing camps. Dialogue between the two has often been heated. In one camp are the "enthusiasts" who consider the evidence sufficient for encouraging Western society as a whole to restrict dietary sodium intake. Such dietary change would, they feel, lower arterial pressure overall, prevent the onset of hyperten-sion in many, and most likely reduce the complications of high blood pressure. Unlike antihypertensive drug therapy, diet modification would have few if any undesirable effects; thus, for those in whom no benefit was seen at least no harm would result. The contrary camp houses the "skeptics." They claim the evidence is insufficient to justify attempts at lowering dietary sodium for the whole of Western society or even for all mild hypertensive patients. Skeptics emphasize that reports are conflicting on relationships between the level of sodium intake and blood pressure in both animals and humans; that the effects of short-term reductions in dietary sodium on arterial pressure in humans are disputed; that there is little information on the effects of sodium restriction over prolonged periods; and that there is no evidence that the complications of hypertension can be avoided by diet modification. Further, the skeptics are unwilling to accept that dietary changes may necessarily be harmless. My aim is to look at current evidence together with the views of enthusiasts and skeptics and to reach a final, but personal, conclusion as to whether we are sufficiently informed to advise a reduction in dietary sodium of a realistic nature (to around 80 mmol/day) for Western society. Before pursuing this course, however, I should make some observations. First, the literature is vast, and I shall not attempt here to quote all relevant studies. Second, there are special circumstances where moderate restriction of dietary sodium is of accepted benefit, in particular during drug treatment for hyperten-sion.'" 1 My present discussion addresses the advisability of limiting dietary sodium in whole populations. Third, the design of many studies relating sodium to blood pressure , especially those in humans, …