To salt or not to salt? To regulate right away or conduct more research first? My Findings column takes a skeptical look at the case for salt reduction. (You can also check out my olleague Jane Brody’s recent column on salt .) The salt wars can be vicious, pitting what I call the salt reformers against skeptics who say there isn’t enough evidence yet to justify public policies restricting salt levels. The reformers want immediate action; the skeptics want to see a randomized clinical trial.

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the salt skeptics can point to all kinds of problems with the reformers’ evidence, too, like the oft-repeated claim that Americans are eating more salt than they did previously (as stated, for instance, in this report from the Center for Science in the Public Interest , which advocates restricting salt). This supposed increase is based on surveys asking people’s recollections of what they ate. But the skeptics say that there isn’t a clear long-term trend in those numbers, and that the numbers themselves are suspect because they’re based on estimates based on people’s imperfect recollections of what they ate — and don’t include, for instance, how much salt people sprinkle on their food from a shaker.

The most precise way to chart daily salt consumption — the method used in the experiments involving low-sodium diets — is to measure the salt excreted in urine collected over a 24-hour period, and researchers on both sides say that these measures don’t reveal a clear upward trend in recent decades. The skeptics say the trend looks flat; the reformers say that they suspect consumption might be increasing, but that they can’t be sure.

“The data is quite murky,” said Lawrence J. Appel of Johns Hopkins University, who advocated public action to reduce salt levels in a recent editorial in The New England Journal of Medicine . “We just don’t have great data on sodium trends over time. I wish that we did. But I can’t tell you if there’s been an increase or decrease.”