Controversial studies say low sodium intake may pose risks

August 18, 2014 in Heart Health, Nutrition Topics in the News

Controversial studies say low sodium intake may pose risks

Two new studies published in the New England Journal of Medicine go against conventional wisdom that you should cut back on sodium, but some experts are criticizing the findings.

In one study that looked at death and heart disease, researchers found that low-salt diets may not be as beneficial as many experts believe, and might even pose a hazard.

The other, focused on blood pressure effects, found that people with a moderate salt intake didn't benefit from reducing their consumption as much as people in the high-salt group.

The researchers from McMaster University in Hamilton, Ontario say these studies show that there is an optimal level of sodium intake, and lower is not necessarily better.

A third international study, published in the same journal, supports the conventional wisdom that there's a direct link between less salt and better health, and found no evidence that extremely-low levels of sodium are dangerous.

One thing all three studies confirm: too much salt is bad for you. High amounts contribute to high blood pressure, stroke, heart attack, kidney problems and heart failure.

That third study concluded that high salt intake was responsible for 1.65 million heart disease deaths worldwide in 2010. It's based on computer models, surveys of salt use in 66 countries and 107 published studies.

Worldwide, daily consumption is usually 3 to 6 grams of sodium, which translates to 7.5 to 15.0 grams of salt. That's well above the limit of 1.5 to 2.4 grams of sodium each day recommend by the World Health Organization, the American Heart Association and other organizations.

The analysis uncovered no danger at low levels or below.

According to the McMaster researchers, the relationship between sodium and bod pressure seems is more complicated than previously thought, and the health benefits of lowering salt intake aren’t the same for everyone.

The most dramatic evidence was the study that looked at the link between sodium intake and death, heart attacks and strokes using urine samples to estimate sodium consumption.

The study found that consuming less than 3 grams of sodium per day increased the risk of death or major cardiovascular events by 27 percent compared to people who consumed 4 to 6 grams daily. The optimum sodium level was 3 to 6 grams per day.

But other experts say the weight of the evidence suggests that there is no risk in aggressive salt reduction.

The McMaster University researchers derived their results from a study called the PURE study, which assessed sodium consumption based on a single urine sample collected each morning. According to experts, that is an unreliable method for measuring salt intake. The gold standard is 24-hour urine collection.

The American Heart Association position has not changed in response to the PURE paper; the association recommends less that 1.5 grams of sodium daily.

Source: New England Journal of Medicine, online August 13, 2014.

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