Christine Palumbo, M.B.A., R.D.

Environmental Nutrition Newsletter

Does everyone need to reduce their sodium levels, or only those who are sensitive to this mineral? This long simmering controversy rages on.

While the U.S. Dietary Guidelines, National Heart, Lung and Blood Institute, National High Blood Pressure Education Program and most medical organizations say we should all reduce the sodium in our diets, some researchers pooh-pooh that idea. It's their contention that only those who are "salt sensitive" need be concerned.

What is salt sensitivity?

Salt sensitivity means that your blood pressure will respond when you change your dietary salt intake, explains Paul W. Sanders, M.D., F.A.C.P., director of the Nephrology Research and Training Center at the University of Alabama at Birmingham. It appears that some of us have salt sensitivity and react directly to salt intake, while others do not.

Are you salt sensitive?

So, how do you know if you're sensitive to salt? Unfortunately, a practical, reliable test for salt sensitivity has yet to be developed, although researchers are currently seeking to establish one. While scientists have much to learn about the mechanisms of salt sensitivity, they have identified various factors that can place you at higher risk for it, such as increased age, genetic variations, how well your kidneys excrete waste, and even race--salt sensitivity rates are higher among African-Americans.

According to a 1996 article in the journal Hypertension, 26 percent of people with normal blood pressure and 51 percent of people with high blood pressure were found to be salt sensitive.

"About a quarter of otherwise healthy adults are salt sensitive and likely are unaware that they respond to increases in dietary salt intake with an increase in blood pressure," says Sanders.

Research is uncovering new information that indicates salt sensitivity carries its own risks that go beyond high blood pressure. One study reported in the 2001 issue of Hypertension found that salt-sensitive subjects with normal blood pressure had similar death rates as people with high blood pressure. Salt sensitivity has also been linked recently with increased risk for cardiovascular events and metabolic syndrome (a cluster of conditions that increase risk for heart disease and diabetes.)

As we wait to more fully understand this emerging field of science, experts suggest that salt-sensitive people can take practical approaches to managing their condition, such as limiting sodium and monitoring blood pressure levels.

Cutting back sodium brings benefits for all. Whether you're salt sensitive or not, you've probably heard that you should limit your dietary sodium to 2,300 mg per day. Yet, as many as 75 percent of Americans consume more than the suggested maximum, according to Thomas Frieden, M.D., M.P.H., director of the U.S. Centers for Disease Control and Prevention (Atlanta, GA).

Even more compelling, the American Heart Association published new guidelines this year calling for all Americans to reduce their daily intake of sodium to just 1,500 mg. This was previously the recommended limit for people at higher risk for cardiovascular disease.

A wealth of information suggests that lower sodium intakes benefit health. If Americans, as a whole, cut a modest amount of salt from their daily diet, there would be an estimated 155,000 fewer heart attacks and strokes annually, according to a study published in January, 2010 in the New England Journal of Medicine. This could be as beneficial to your health as quitting smoking, losing weight, and using medications to reduce elevated cholesterol and hypertension.

According to another study published in April 2009 in PloS Medicine, overall sodium reduction may be as effective in preventing death as dietary strategies like eliminating trans fats and increasing fruit and vegetable consumption. And reducing sodium to about 2,000-2,600 mg per day improved cardiovascular health and reduced the rate of heart attacks and stroke by 25 percent, despite only small reductions in blood pressure, as was reported in a 2007 study in the British Medical Journal.

Research even suggests that lowering your salt intake can reduce the risk of gastric cancer, end-stage kidney disease, left ventricular hypertrophy, congestive heart failure, osteoporosis, and bloating.

But sodium restriction for all still sparks controversy in the research world.

"This is still a highly contentious field. There has been suggestion that the salt-resistant individual might not benefit from salt reduction, since his/her blood pressure can sometimes increase on a low salt diet," says Sanders. "But when considering dietary salt intake, it's not just about the blood pressure. There are direct effects of salt intake on vascular function that are independent of blood pressure and might contribute to the excess mortality observed with increased salt intake."

EN's bottom line on sodium intake

Until there is a simple diagnostic test developed for salt sensitivity, the weight of evidence leans in favor of reducing your sodium intake as much as possible. As Sanders suggests, "The days of ignoring the beneficial effects of reduced salt intake should be behind us. Salt is an acquired taste that can be modified, and the health of Americans will benefit from even modest reductions in salt intake."

There are two complementary ways you can lower your sodium intake: Select and prepare foods with little or no salt, and reduce the amount of sodium you get from processed and prepared foods. With about 75 percent of our dietary sodium intake coming from processed and prepared foods, try our tips to skim salt from your diet.

 

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Health - A Sensitive Issue: Salt Restriction