Participation in New York City's new anti-salt campaign, which aims to reduce the sodium content of restaurant and packaged food by an average of 25 percent in the next five years, is voluntary for now. But that is also how the city's trans fat ban got started; when restaurants declined to cooperate, they were forced. City officials are downplaying the possibility that recalcitrant volunteers will be conscripted. "There’s not an easy regulatory fix," Associate Health Commissioner Geoffrey Cowley told The New York Times. "You would have to micromanage so many targets for so many different products." And when have government bureaucrats ever tried to micromanage business practices?

Even if it does not become legally mandatory, the city's salt assault is astonishingly presumptuous. Because it requires the participation of restaurant chains and food manufacturers, it will, if successful, affect the diet of the entire country. Such a nationwide shift is not justified even by the standards of "public health" paternalism, since it could do more harm than good. "We all consume way too much salt," claims New York City Health Commissioner Thomas Farley. But as I noted in my 2003 Reason article about the Center for Science in the Public Interest (which back in the 1970s was calling salt "the deadly white powder you already snort"), that position is more an article of nutritional faith than an established scientific proposition. Reviewing the controversy over salt reduction in a 2008 Esquire article, John Mariani summed up the evidence this way:

Studies show that 30 percent of the Americans who have high blood pressure would greatly benefit from a low-sodium diet. But that's about 10 percent of the overall population—the rest of us are fine with sodium.

Furthermore, skeptics such as Michael Alderman, editor of the American Journal of Hypertension, worry that a substantial nationwide reduction in salt consumption could have unintended negative health consequences. "They want to do an experiment on a whole population without a good control," Alderman told the New York Daily News. "That's not science." In a 2000 review of the evidence, Alderman warned:

The question...is whether the beneficial hypotensive effects of sodium restriction will outweigh its hazards. Unfortunately, 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.

Previous Reason coverage of New York's anti-salt crusade here, here, and here.