Tuesday, February 23, 2010

Get thinner by eating more salt?

Dr. [David] McCarron and his colleagues analyzed surveys from 33 countries around the world and reported that, despite wide differences in diet and culture, people generally consumed about the same amount of salt. ...

The results were so similar in so many places that Dr. McCarron hypothesized that networks in the brain regulate sodium appetite so that people consume a set daily level of salt. If so, that might help explain one apparent paradox related to reports that Americans are consuming more daily calories than they used to. Extra food would be expected to come with additional salt, yet there has not been a clear upward trend in daily salt consumption evident over the years in urinalysis studies, which are considered the best gauge because they directly measure salt levels instead of relying on estimates based on people’s recollections of what they ate. ...

As Americans ate more calories, they could have eased up on some of the saltier choices so that their overall sodium consumption remained constant. By that same logic, [McCarron] speculated, if future policies reduce the average amount of salt in food, people might compensate by seeking out saltier foods — or by simply eating still more of everything. ...

If you track how many strokes and heart attacks are suffered by people on low-salt diets, the results aren’t nearly as neat or encouraging, as noted recently in JAMA by Michael H. Alderman, a hypertension expert at Albert Einstein College of Medicine. A low-salt diet was associated with better clinical outcomes in only 5 of the 11 studies he considered; in the rest, the people on the low-salt diet fared either the same or worse.
--John Tierney, NYT, on reasons to reach for the salt shaker 

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