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As-salt on Science
As-salt on Science
January 13, 2010
Originally published in The New York Post
On Monday, city officials rolled out an initiative to curb the salt content in manufactured and packaged foods. But the idea behind it -- that salt intake has reached extreme levels in America -- is a myth, and this "solution" wouldn't work, anyway.
City Health Commissioner Dr. Thomas Farley aims to lead a national campaign to reduce the amount of salt in manufactured foods by 25 percent over the next five years. Cutting salt intake is supposed to reduce hypertension-related health problems. But while doctors may advise particular patients to cut down on salt, the science tells us that this is not a public-health problem.
Nutritionists at the University of California/Davis just published the first and only study to address salt intake and public policy. They found that people are naturally inclined to regulate salt intake to physiologically determined levels by unconsciously selecting foods to meet their needs -- and even the most extreme interventions don't do much.
The UC Davis study (published in the October issue of The Clinical Journal of the American Society of Nephrology) looked at data from more than 19,000 individuals from 33 countries worldwide. It determined that daily sodium intake ranges only from 2,700 milligrams to 4,900 mg, with the worldwide average of 3,700 mg.
It also determined that the average American consumes about 3,400 mg a day -- disproving the claim spread by advocates such as the Center for Science in the Public Interest that US salt consumption is out of control.
In other words, Farley's trying to fight a problem that doesn't exist. Worse, his new guidelines say that daily sodium intake for most people shouldn't exceed 1,500 mg -- which is a ridiculous 45 percent below the bottom of the normal consumption range the UC Davis study identified, and a full 60 percent lower than the worldwide average.
The researchers also cite decades of research describing the specific mechanism by which the central nervous system, acting together with several organ systems, controls our appetite for salt. One of the studies they cite involved hundreds of participants in what was to be a three-year sodium-intake intervention, with the goal of reducing daily intake to 1,850 mg.
But after six months, researchers noted that participants were simply unable to cut sodium intake below about 2,750 mg a day -- close to the bottom of the range the UC Davis study identified.
Another study had used intensive dietary counseling to get participants to cut daily sodium intake to an average of 1,775 mg over four weeks. After that, the subjects, while still receiving counseling, were randomly split into two groups -- one getting a sodium tablet, the other a placebo.
Those who got the placebo still raised their intake by nearly 1,000 mg, while those on the sodium tablet actually cut their dietary-sodium consumption to compensate.
These people didn't know how much sodium they were getting -- they unconsciously changed their diets to match what their bodies "knew" they needed.
The UC Davis study also cites surveys showing that sodium intake in the United Kingdom has "varied minimally" over the last 25 years, despite a major government campaign to reduce it.
Overall, the researchers found, salt intake "is unlikely to be malleable by public policy initiatives," and attempts to change it would "expend valuable national and personal resources against unachievable goals."
The New York guidelines are voluntary -- for now. But the city's ban on trans fats started that way, too. And the federal Food and Drug Administration has also been looking to get in on the action -- it may classify it as a "food additive," subject to regulation, sometime this year.
But this campaign isn't about public health -- it's about grandstanding on a pseudo-issue ginned up by activists, when science clearly shows that there's neither a crisis nor a way for the government to actually alter our salt intake.
All these initiatives do is win headlines for ambitious policymakers (New York's last health commissioner parlayed his trans-fat activism into a promotion to FDA chief), while making food slightly more costly and leaving a bad taste in the mouths of consumers -- literally.