Features August 2013 Issue

Making Sense of the Salt Debate

Is 2300 mg of sodium a day safe for everyone, or do some people need to consume less? Leading doctors disagree about how low we should go.

High blood pressure (hypertension) is a risk factor that contributes to heart attack, stroke and kidney disease. A diet low in sodium (the main ingredient in salt) can help prevent hypertension. The question is, how little sodium should you consume?
For decades, it has been known that blood pressure starts to rise when sodium consumption exceeds 2,300 mg/day. This has led most U.S. and European societies to set the upper limit of sodium consumption at 2,300 mg/day.

But new recommendations suggesting that people at increased risk due to hypertension, diabetes, chronic kidney disease, age (over 51) or race (African-American) should lower their sodium intake to 1,500 mg/day has ignited a firestorm of controversy among physicians. Some agree with the recommendation. Others, like Cleveland Clinic hypertension expert Joseph Nally, MD, express concern with the quality of the evidence for a very low sodium diet.

“There’s no doubt that higher sodium intake confers risk, but there’s little clear-cut scientific evidence supporting a very low salt diet,” he says. “When my colleagues and I suggest a low-salt diet, we advise 2,000 to 2,300 mg of sodium a day.”

How the conflict began
In 2010, the Department of Agriculture reviewed studies on salt consumption that had been performed since the recommended level of 2,300 mg/day was established in 2005. They concluded that 2,300 mg/day was sufficiently low for the general population, but recommended that patients at risk for kidney disease, heart disease and stroke should lower their sodium intake to 1,500 mg/day. The American Heart Association firmly supported this recommendation.

The Institute of Medicine (IOM) responded by reviewing the same studies. However, they found little evidence that sodium intake ranging from 1,500 to 2,300 mg/day were beneficial, and some evidence suggesting very low sodium intake may be harmful in people with diabetes, kidney disease or cardiovascular disease. Because they felt none of the evidence in favor of benefit or harm was strong enough to indicate that at-risk patients need a different sodium intake than the general population, they recommended that the established established, recommended sodium intake of 2,300 mg/day remain in place until additional well-run studies support a different conclusion.

Sodium and you
With the American Heart Association and Department of Agriculture in one corner of the ring, and the prestigious IOM in the other, doctors are unsure how little sodium is safe for at-risk patients to consume. “There’s even more concern that people will think sodium consumption doesn’t matter,” says Dr. Nally. “These IOM recommendations should not be interpreted that people do not need to limit their dietary sodium intake.”
Nothing could be further from the truth. The relationship between sodium intake and your health is vital.

If you have hypertension, eating a low-salt diet can make your blood pressure medication more effective.

The final word
So how little sodium should you consume? According to Dr. Nally, the IOM report has the answer.

“Moderate salt intake—2,300 mg/day—is recommended for the general public as well as for those at increased risk. There is not enough high-quality scientific evidence to recommend a lower sodium threshold at this time,” he says.

Doctors acknowledge that lowering sodium intake to 1,500 mg/day is very difficult to achieve, but 2,300 mg/day may not be easy either.

“The average American consumes 3,400 mg/day of sodium. This means most Americans should restrict their dietary sodium,” says Dr. Nally.

As for the future, no one can be sure these recommendations won’t change someday, and further debate will ensue. But studies will have to be done differently to draw a different conclusion.

“In the past, studies only looked at the effects of sodium on blood pressure. Future studies should look for the impact of lower sodium intake on cardiovascular disease and stroke,” says Dr. Nally.


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