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With a Grain of Salt: Why You May Not Need to Limit Your Sodium Intake

 

There's No Need to Toss Your Saltshaker

Chances are, you feel guilty every time you sprinkle the white stuff on your food these days. And no wonder: Many health groups have declared sodium a public enemy. The Institute of Medicine, a branch of the National Academy of Sciences, says we should consume no more than 2,300 milligrams (about one teaspoon) of the mineral daily to help reduce the risk of heart attack and stroke. But some experts question whether that advice is necessary — or even healthy — for everyone. "Cutting sodium by about 50 percent lowers blood pressure, which could lead to a reduction in cardiovascular disease," says Michael H. Alderman, MD, professor of epidemiology and population health at Albert Einstein College of Medicine in the Bronx, New York. "However, no clinical trials have ever been conducted to show that's the case."

In fact, some observational studies have found that a sodium intake of less than 2,300 milligrams a day has no effect on heart disease, and other research reveals that people who consume less salt are actually more likely to have heart attacks or strokes. "The theory that reducing sodium will make us healthier may be true, but it needs to be proved before we make widespread rec­ommendations," Dr. Alderman notes. Until more research is done, he says, there's no evidence that healthy women with normal blood pressure need to limit salt.

If you have risk factors for heart disease, however, talk with your doctor about watching your intake. A recent study found that cutting sodium back by at least 400 milligrams a day — about one-sixth of a teaspoon of salt (roughly an ounce of pretzels) — may be beneficial. "Even a small decrease will take some pressure off the arteries and keep them stronger longer," says Lawrence J. Appel, MD, professor of medicine, epidemiology, and international health at Johns Hopkins Medical Institutions in Baltimore.

Fact #1: Sodium keeps you healthy.

Despite the bad rap it gets, "sodium is critical to maintaining every cell in the body," Dr. Appel says. "But we don't need very much of it," he adds. The mineral helps control your heart rate, aids digestion, and keeps you hydrated during exer­cise, among other things. Recently an analysis of data from more than 19,000 men and women in 33 countries over more than 20 years found that people consistently consume an average 3,000 to 4,800 milligrams of sodium every 24 hours. "We think this range may be the amount the body requires to be at its healthiest and assure the best blood flow to critical organs, including the brain, heart, and kidneys," says study coauthor David McCarron, MD, an adjunct professor in the department of nutrition at the University of California, Davis. For now, however, the Institute of Medicine says adult women need no more than 1,500 milligrams of sodium a day to meet their bodies' needs.

Fact #2: Salt is crucial to your workout.

The sodium in your bloodstream helps keep your muscles functioning optimally when you exercise. You lose the mineral when you sweat, though; the average person may perspire away about 500 milligrams of sodium during an hour-long workout, says Nancy Clark, RD, author of Nancy Clark's Sports Nutrition Guidebook. "Most of us get enough from our meals and snacks so that we don't need to worry about replacing what we lose," she says. "But if you're repeatedly exercising in hot or humid conditions or training for a marathon, you may feel better if you up your intake slightly." To figure out how much to replenish, weigh yourself before and after a sweat session, taking into account the amount of fluid you consumed. So if you're one pound lighter but you drank 16 ounces of water during your workout, you've really lost a total of two pounds. "If you're down two or more pounds, have a handful of pretzels to replace the sodium you've lost," Clark advises.

How to Avoid Bloating, Loss of Calcium

Fact #3: You'll feel sodium's side effects; your husband probably won't.

The morning after a salty dinner, you're likely to feel like the Michelin Man. Your guy? Not as much. "The more sodium you consume, the more water your body retains to dilute it," says Suzanne Trupin, MD, director of Women's Health Practice in Champaign, Illinois. "Women have a smaller blood volume than men, which means that even tiny increases in salt can cause puffiness." Hormones also play a role. "Your body is primed to hold on to water a day or two before your period to prep for pregnancy or to compensate for the fluid it will lose through menstruation," Dr. Trupin says.

To beat bloat, limit the amount of processed and prepared foods you eat. "They account for almost 80 percent of our sodium intake," Dr. Appel says. "Check labels; ideally a product should have no more than 200 milligrams of sodium per serving, and a full meal should have less than 600." Skip processed foods several days before your period and drink plenty of water. "The better hydrated you are, the quicker your system can filter out excess sodium," Dr. Trupin explains.

Fact #4: Too much salty stuff can hurt your bones.

Eat a particularly salty item, like a dill pickle, and you may lose calcium. That's because sodium and calcium are excreted through urine, and too much of one substance increases the loss of the other, explains Robert P. Heaney, MD, professor of medicine at Creighton University's Osteoporosis Research Center in Omaha. To protect your bones, Dr. Heaney recommends eating enough dairy to get 1,200 to 1,500 milligrams of calcium daily. "Spread your servings throughout the day," he says. "You'll absorb the calcium more efficiently that way."

Originally published in FITNESS magazine, February 2011.

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