New York City is trying to cut the salt in prepared food, a policy that could have a nationwide impact since it relies on the cooperation of restaurant chains and manufacturers whose products are sold throughout the country. Yet the science underlying the project is so shaky that the resulting dietary changes could do more harm than good.
New York City Health Commissioner Thomas Farley aims to reduce the sodium content of restaurant and packaged food by an average of 25 percent in the next five years because "we all consume way too much salt." But there is remarkably little evidence to support that assertion. Decades after the federal government began urging Americans to cut back on salt, the advice remains controversial among scientists. While studies suggest that a minority of people with high blood pressure—about 30 percent—would benefit from a low-salt diet, that group represents just 10 percent of the population.
In a 2000 review of the evidence, Michael Alderman, editor of the American Journal of Hypertension, warned: "Few data link sodium intake to health outcomes, and that which is available is inconsistent. Without knowledge of the sum of the multiple effects of a reduced sodium diet, no single universal prescription for sodium intake can be scientifically justified." After Farley announced his plan in January, Alderman told the New York Daily News, "They want to do an experiment on a whole population without a good control. That's not science." Alderman and other skeptics worry that a substantial nationwide reduction in salt consumption could have unintended negative health consequences.
For now, participation in New York's salt assault is voluntary. But that's also how the city's trans fat ban started.