Seasoning for an active lifestyle.

the Institute of Medicine recently assembled a panel of U.S. and Canadian scientists to examine and update sodium chloride (and other electrolyte) consumption recommendations for healthy adults. But how do these new findings relate to athletes' salt intake?

The report recommends healthy adults consume about 3.8 grams of salt (1.5 g of sodium, 2.3 g of chloride) per day, not to exceed 5.8 g (2.3 of sodium, 3.5 of chloride). It advises athletes to consume more than this to offset sweat loss. But how much more? E. Randy Eichner, MD, hematologist, internist for the Oklahoma Sooners and Running & FitNews[R] editorial board member, says, "No practical way exists to gauge sodium needs as precisely as fluid needs." (Fluid loss can be determined by weighing athletes before and after exercise.) He notes that sodium levels in sweat vary greatly among people, as do sweat rates. Genes and other factors play a role. For example, sweat sodium losses reduce as an athlete becomes acclimatized.

"Some athletes can lose staggering amounts of salt in the heat," says Eichner. Indeed, Larry Kenney's recent look at sodium requirements for the Gatorade Sports Science Institute estimated salt loss for a "typical" linebacker during "two-a-days" at 17 grams. These are the notoriously grueling double-practice days associated with summer football training. In a study of Oklahoma University football players prone to heat cramping, Eichner measured average salt loss at nearly five teaspoons (25 grams) per day. One study of heat cramping tennis players found 15 grams of salt loss in one hour.

Practically speaking, there are certain signs you may look for that could indicate you needn't obsess about sodium intake. To a small extent, dietary sodium influences sweat sodium, but the kidneys flush most of the excess. "If you cake in salt, if sweat burns your eyes, stings abrasions, tastes salty when it trickles in your mouth, or if you heat cramp or get dizzy when you first stand up in the morning, you need more salt." Athletes who are "salty sweaters" are at greater risk for hyponatremia, a condition in which blood sodium levels become dangerously low. They should liberally salt their food, favor sports drinks to water during workouts and consume salt-rich foods regularly, especially in heavy training months in hot and humid climes.

(Phys. Sportsmed., 2004, Vol. 32, No. 4, pp. 12, 41; Institute of Medicine: Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate, 2004, www.nap.edu; Dietary Water and Sodium Requirements for Active Adults, Gatorade Sports Science Exchange No. 92, 2004, www.gssiweb.com; Playing Tennis in the Heat: Can Young Players Handle It? ACSM Current Comment, August 2002, www.acsm.org; personal corresp. Randy Eichner, MD, FACSM, Oklahoma University Medical School)