Salt Is Good For You?

The attack on sugary sodas is just the latest salvo in NYC Mayor and Nanny-in-Chief Michael Bloomberg's bland food assault. Two years ago, his target was salt—advocating a 25 percent cut in salt in packaged and restaurant foods to be implemented over the next five years. In Sunday's New York Times, health science reporter Gary Taubes has an excellent op/ed exposing how anti-salt campaigners ignore the accumulating scientific evidence that eating salt is not a huge public health problem. Taubes notes that even as far back as 1998 the evidence that current levels of salt consumption was unhealthful was equivocal at best. Now he reports: 

While, back then, the evidence merely failed to demonstrate that salt was harmful, the evidence from studies published over the past two years actually suggests that restricting how much salt we eat can increase our likelihood of dying prematurely. Put simply, the possibility has been raised that if we were to eat as little salt as the U.S.D.A. and the C.D.C. recommend, we'd be harming rather than helping ourselves….

The idea that eating less salt can worsen health outcomes may sound bizarre, but it also has biological plausibility and is celebrating its 40th anniversary this year, too. A 1972 paper in The New England Journal of Medicine reported that the less salt people ate, the higher their levels of a substance secreted by the kidneys, called renin, which set off a physiological cascade of events that seemed to end with an increased risk of heart disease. In this scenario: eat less salt, secrete more renin, get heart disease, die prematurely.

With nearly everyone focused on the supposed benefits of salt restriction, little research was done to look at the potential dangers. But four years ago, Italian researchers began publishing the results from a series of clinical trials, all of which reported that, among patients with heart failure, reducing salt consumption increased the risk of death.

Those trials have been followed by a slew of studies suggesting that reducing sodium to anything like what government policy refers to as a "safe upper limit" is likely to do more harm than good. These covered some 100,000 people in more than 30 countries and showed that salt consumption is remarkably stable among populations over time. In the United States, for instance, it has remained constant for the last 50 years, despite 40 years of the eat-less-salt message. The average salt intake in these populations — what could be called the normal salt intake — was one and a half teaspoons a day, almost 50 percent above what federal agencies consider a safe upper limit for healthy Americans under 50, and more than double what the policy advises for those who aren't so young or healthy. This consistency, between populations and over time, suggests that how much salt we eat is determined by physiological demands, not diet choices.

One could still argue that all these people should reduce their salt intake to prevent hypertension, except for the fact that four of these studies — involving Type 1 diabetics, Type 2 diabetics, healthy Europeans and patients with chronic heart failure — reported that the people eating salt at the lower limit of normal were more likely to have heart disease than those eating smack in the middle of the normal range. Effectively what the 1972 paper would have predicted.

Proponents of the eat-less-salt campaign tend to deal with this contradictory evidence by implying that anyone raising it is a shill for the food industry and doesn't care about saving lives. An N.I.H. administrator told me back in 1998 that to publicly question the science on salt was to play into the hands of the industry. "As long as there are things in the media that say the salt controversy continues," he said, "they win."

How dare Taubes challenge a "scientific consensus"! 

Go here to read the whole op/ed. Go here for links to previous reporting by Reason on the salt assault.