Saturday, January 31, 2009

Salt fascists are coming

The NY Times reports:
After a string of victories over smoking, trans fats and calories, Dr. Frieden, the commissioner of New York City’s Department of Health and Mental Hygiene, is waging a new campaign: to lower the amount of sodium America eats. ...

Lowering salt consumption, along with stopping smoking, are two areas in which a broad public health effort can have the most impact on the most people, Dr. Frieden said.

Key to the plan is a gradual reduction in sodium levels. The theory is that if the salt disappears slowly enough, consumers will not notice. ...

But public health officials say there is a strong consensus that salt leads to higher rates of heart attacks and strokes.

That consensus alarms Dr. Michael Alderman, editor in chief of the American Journal of Hypertension, who thinks more clinical studies need to be done. And, he says, wild swings in dietary regulation haven’t always worked out.

Even trans fat, in the form of margarine, was once promoted by health officials as healthier than butter. It turns out that trans fats were worse for heart health than saturated fats.

“Diet is an incredibly complicated business,” Dr. Alderman said.
That last point is correct. The whole reason trans-fats were introduced into our diets was that diet do-gooders claimed that it was healthy. They never had any good scientific evidence that trans-fats were any healthier than anything else, but no one questioned them.

Now they are after salt. Dire warnings like the above come from others such as the Center for Science in the Public Interest. Again, there is no evidence of any measurable overall health benefit to lowering salt intake.

Unless you have high blood pressure or hypertension, there is no reason to be concerned about sodium at all. If you are on blood pressure lowering drugs, then your salt intake may have a slight effect on how much of the drug you might have to take to bring your blood pressure down to normal levels. If you are in that position and that matters to you, then go ahead and lower your sodium intake. But for everyone else, salt is good for you, and it is silly and harmful for public health officials to wage a war against sodium.

Update: Medical prof Michael Alderman responds:
If such a large reduction were actually to be achieved, however, New Yorkers would consume less sodium than people in most other developed countries do. And there is a possibility that such a big change in one element of their diet might have unintended harmful consequences. Prudence requires that logic and good intentions also be supported by strong evidence that such an action would be safe.

Throughout history, efforts have been made to reform the human diet by changing individual characteristics of it, and some of these changes have had unexpected harmful effects. In the 1950s, for instance, pregnant women were urged to strictly limit their weight gain to avoid pre-eclampsia, a syndrome characterized by high blood pressure, fluid retention and kidney problems. Enough women apparently followed this advice that the number of underweight babies — and of infant deaths, some attributable to low birth weight — increased.

More recently, the federal Dietary Guidelines have been criticized by medical researchers as contributing to an increasing prevalence of obesity in the United States, in part by encouraging people to eat too much low-fat food.

In both instances, respected authorities instituted reasonable ideas without having the evidence to know whether their policies might backfire. ...

Only one such rigorous clinical trial on salt intake has been reported so far, and it focused on patients with fairly advanced heart problems. As it turned out, the group that adhered to a lower sodium diet actually suffered significantly more cardiovascular deaths and hospitalizations than did the one assigned to the higher sodium diet.
The AMA says:
The American Medical Association applauds the New York City Department of Health and Mental Hygiene for embarking on a campaign to urge processed-food manufacturers to voluntarily reduce the salt content in their products. ...

A national reduction in the amount of sodium in processed foods is clearly needed ...
The AMA has a very poor record on nutritional advice. I am going with the scientific studies instead.

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