Salt
Credit: David Freund / Getty Images

Bad Rap: We've known for years that salt causes high blood pressure and heart disease – not that Americans heed these warnings. A study from the Center for Science in the Public Interest, based in Washington, DC – the people who made us aware of trans fats – says that reducing sodium consumption by half in the United States would save an estimated 150,000 lives a year. But if what you take from such sobering news is that you should avoid salt altogether, hold on. You need some salt – especially if you want to be at the top of your game. Yes, the report provides valid warnings for average, sedentary Americans, and points to the main culprit, sodium hidden in things like white bread and pasta sauce.

Reality Check: But it fails to consider the special segment of the population that may not consume enough salt when their bodies absolutely need it. If you train for marathons, go on lengthy bike rides, are a long-distance swimmer, or compete in triathlons, you're one of these people. "Even if you're drinking a bottle of electrolyte-laced sports drink during a workout, you're still losing more salt than you take in," says Alicia Kendig, a sports dietitian with Carmichael Training Systems in Colorado Springs who designs nutrition programs for professional and amateur triathletes, cyclists, and runners. "You need that sodium back because it enables the body to absorb more fluids faster. And you need to stay hydrated if you want to maintain your performance." (On average, a marathoner loses between 700 and 1,600 milligrams of sodium per hour.) Still, considering that otherwise healthy snacks can be filled with sodium (for instance, a four-ounce serving of cottage cheese typically contains 460 milligrams), you don't need to shake salt on anything. As an easy rule of thumb, Kendig recommends downing one 20-ounce bottle of sports drink for each hour of exercise, and one immediately afterward to replenish fluids. "That should get your sodium levels close to normal again," she says – just enough, but not too much.