Hype about salt

To eat or not to eat is not the question, says a critic of 'low salt' theory

Published: Monday 30 November 1998

On the briny: IF you are above 40, suffering from high blood pressure and heart problems, your doctor must have told you to eat less salt. But very few of us know that the ,to eat or not to eat salt' debate is eternal in medical sciences. Researchers say that by making salt out to be the main culprit, they have distracted attention from factors actually responsible for causing these diseases. The latest critic is David McCarron of the Oregon Health Sciences University, Portland,,USA. He says that salt alone is not the culprit, and by making it out to be as one, attention is deflected from the actual problems, such as lack of vegetables in the diet. The main reasons for heart diseases and other stress-related ailments are our lifestyles and consumption of processed food, he says. The 'low salt' theory has been 'sold' by the government because most want to believe in it (Science, Vol 281, No 5383).

The US has provided most of the data supporting the theory that high salt intake is bad for health. What has been overlooked is that there are many us researchers working on hypertension who argue that the data supporting universal salt reduction has never been compelling. The include physicians include those from the American Heart Association, and other European and international societies. Also, it has never been demonstrated that a blanket reduction of salt in diet would mean freedom from long-term unforeseen side-effects.

The relationship between salt and health is very complex. High salt intake leads to higher sodium concentration as the body retains more water. This, in turn, makes the kidneys respond promptly by sending out excess salt through urine. Because of excessive retention of water, there may be a slight increase in blood pressure in some people. What further complicates the issue is the interplay of over 50 different nutrients, growth factors, and hormones. For instance, sodium is important for maintaining the blood volume, potassium for expanding and contraction of blood vessels and calcium for maintaining the tone of the blood vessels. If caloric intake is increased, the nervous system responds by constricting the blood vessels, thus raising the blood pressure. Decreased intake reduces the blood pressure. And there are also factors like the age, sex, and perhaps even race that matter.

Many researchers are encouraging an unbiased critical look at the whole issue of the relationship of salt intake and overall health, especially since dietary advice on one component may not achieve the desired social outcome. According to Bill Harlan of the Office of Disease Prevention in the National Institutes of Health, Bethesda, USA, even with low-fat diets, there has been a steady increase in weight in many people. The issue of salt is equally complex and the only factor that should decide is good science backed by hard data and not opinions that may find favour with public.

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