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Salt Shake-Up: Why Sodium Is Good for You

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Shake It Out

Hi, my name is Sally, and I'm a dietitian who loves salt. I lick it from my fingers when eating popcorn, generously sprinkle it on roasted vegetables, and wouldn't dream of buying unsalted pretzels or low-sodium soup. Even though my blood pressure has always been low, I still feel a little guilty. After all, if we want to lessen our chances of heart disease and stroke, we should all shun salt, right?

Actually, no. When it comes to sodium, not everyone agrees that the best strategy is to go low. In fact, going too low may be downright unhealthy, new research says. And active women may need even more salt than those who are sedentary. To cut through the confusion, we consulted the top experts and analyzed all the latest studies. Here's everything you need to know about the white stuff.

The Super Mineral?

Although sodium often gets lumped into the category of nutritional no-no's, your bod needs it. This mineral, which helps your system send messages to and from the brain and keep your heartbeat steady, is mega-important for active women. In fact, it's a veritable workout secret weapon, no less crucial than your sports bra. It can often help prevent the kind of muscle cramping that cuts exercise sessions short and ruins races. It also helps your body hold on to water, so you stay better hydrated, says Nancy Clark, RD, the author of Nancy Clark's Sports Nutrition Guidebook. Clark recalls one of her clients, a marathon runner who exercised in the heat and complained of being tired all the time. Turns out, she was severely restricting her salt intake. "She didn't use salt in cooking or at the table and chose salt-free pretzels, crackers and nuts. She ate primarily unprocessed 'all natural' foods that are low in sodium," Clark says. When she added a bit of sodium to her diet — sprinkling some salt on her baked potato and into the boiling water before adding pasta — she reported feeling a lot better.

Certain fit women need a lot of salt, says Amy Goodson, RD, a sports dietitian in Dallas. During a vigorous exercise session, most women lose some sodium, potassium and fluid. But "salty sweaters" lose more and thus need to replenish it afterward. (To find out if you fall into this category, see "What to Do.")

The Great Salt Debate

If sodium is so important, how the heck did it become such a villain? For some people, too much of the mineral can make the kidneys retain extra water (that's why it causes bloating), increasing blood volume. That puts more pressure on blood vessels, forcing the heart to work harder. Over time, that can turn into high blood pressure, says Rachel Johnson, PhD, RD, a spokeswoman for the American Heart Association. Because one in three Americans has high blood pressure and eating less salt can help lower hypertension, in the 1970s experts advised cutting back, and suddenly the whole country was on a salt-restrictive kick. According to the most recent Dietary Guidelines for Americans, you should get less than 2,300 milligrams of sodium a day; the American Heart Association takes it even further with their recommendation of 1,500 milligrams a day.

But a recent report from the Institute of Medicine questions whether a low-sodium diet is right for everyone. After reviewing the evidence, the IOM's experts stated there simply wasn't proof that consuming less than 2,300 milligrams a day resulted in fewer deaths from heart disease and strokes. In the American Journal of Hypertension, an analysis of seven studies involving more than 6,000 people found no strong evidence that cutting salt intake reduced the risk of heart attacks, strokes, or death in people with either normal or high blood pressure. "The current recommendations were based on the belief that the lower, the better," says Michael Alderman, MD, a professor emeritus of medicine at Albert Einstein College of Medicine. "But the more recent data on health outcomes show that those guidelines aren't justified."

Going too low may even be dangerous. In a study by Copenhagen University Hospital, a low-sodium diet resulted in a 3.5 percent decrease in blood pressure for people with hypertension. That would be fine, except that it also raised their triglycerides and cholesterol and boosted levels of aldosterone and norepinephrine, two hormones that can increase insulin resistance over time. All of those things are known risk factors for heart disease.

Against the Grain

Now there's even more reason to go ahead and salt your veggies: In March, Danish researchers announced, after analyzing dozens of studies, they had discovered that consuming too little sodium is linked to a greater risk of death. They've determined that the safest range for most people is from 2,645 to 4,945 milligrams of salt a day. Those are numbers that most Americans are already meeting, but, unfortunately, most of that sodium — a whopping 75 percent — comes from packaged and restaurant foods, many of which are loaded with calories, added sugar and even trans fats. The worst offenders are the so-called Salty Six: breads and rolls, cured meats, pizza, soup, poultry, and sandwiches. A typical order of Chinese beef with broccoli has 3,300 milligrams, and a plate of chicken parm comes close to 3,400 milligrams. "Whether it's a fancy restaurant or a greasy diner, chances are it's using a lot of salt," says Michael Jacobson, PhD, the executive director of the Center for Science in the Public Interest, a nonprofit group that has called on the Food and Drug Administration to limit the sodium allowed in processed and restaurant foods.

That leaves fit women who are eating a high-quality diet that includes lots of fresh food, like fruits and vegetables, and whole grains in pretty good shape. "You don't need to be as careful about sodium as some people are if you're doing so many other things right," Jacobson says. Plus research suggests that being active may offer a natural defense against sodium's negative effects. "If you're active, you can probably tolerate more salt in your diet than someone who is not," says Carol Greenwood, PhD, a professor of nutritional sciences at the University of Toronto. That means protection against sodium's impact on blood pressure — and maybe even more. In Greenwood's research, older adults who ate high-salt diets showed more cognitive decline than those with lower salt intakes, but not among those who were physically active. They were protected, regardless of how much salt they ate. "A high level of activity protects blood vessels and the long-term health of the brain," she explains.

Bottom line: If you're active and eating a nutrient-rich diet, sodium shouldn't stress you out. "Of all the things you should worry about," Dr. Alderman says, "you can take that one off the table."

What to Do

Exercising and eating a healthy diet are both excellent safeguards against sodium's harmful effects, so you don't need to toss out your saltshaker. Instead, take this sensible approach to sodium.

Determine if you're a "salty sweater."
After your next push-it-to-the-max workout, hang your tank top up to dry, then watch for the telltale white residue. If you see it, you need even more sodium than the typical fit woman. Novice exercisers tend to lose more salt in sweat (over time, your body adapts and loses less). The smartest way to replenish: Have a post-workout snack that contains sodium — pretzels and string cheese or low-fat cottage cheese and fruit — or add salt to healthy foods like brown rice and veggies. You need to supplement during your exercise session — with sports drinks, gels or chews that contain sodium and other electrolytes — only if you are training for a few hours or are an endurance athlete.

Keep tabs on your BP.
Blood pressure tends to gradually increase with age, so even if your numbers are good now, they may not stay that way. Have your blood pressure checked at least every two years. Hypertension has no symptoms, which is why it's often called a silent killer.

Stick with whole foods.
If you're already trying to cut back on processed foods and dine out less, you're automatically lowering your sodium intake. If your blood pressure is slightly high, start comparing products in the same category, such as soups and breads, to see how their sodium stacks up. A few simple switches can help lower your intake.

Find out your family history.
There's a strong genetic component to hypertension, so fit, healthy people can have high blood pressure if it runs in the family. Keep closer tabs on your blood pressure and your sodium intake if hypertension is in your family tree. About a third of the population is sodium sensitive, which means their blood pressure will respond more dramatically to the substance than other people's will (this is more common in African-Americans and in people who are overweight).

Get more potassium.
The mineral is kryptonite to sodium, blunting its powers. A high-potassium diet can help lower blood pressure. And wouldn't you rather eat more bananas and spinach than nibble on plain popcorn? Other star sources include sweet potatoes, edamame, cantaloupe and lentils. While you're at it, up your intake of low-fat dairy and whole grains too. These have shown to be effective in lowering blood pressure.

Originally published in FITNESS magazine, June 2014.