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People with high blood pressure are often told to eat a low-sodium diet. But a diet that’s too low in sodium may actually increase the risk for cardiovascular disease, a review of studies has found.

Current guidelines recommend a daily maximum of 2.3 grams of sodium a day — the amount found in a teaspoon of salt — for most people, and less for the older people or those with hypertension.

Researchers reviewed four observational studies that included 133,118 people who were followed for an average of four years. The scientists took blood pressure readings, and estimated sodium consumption by urinalysis. The review is in The Lancet.

Among 69,559 people without hypertension, consuming more than seven grams of sodium daily did not increase the risk for disease or death, but those who ate less than three grams had a 26 percent increased risk for death or for cardiovascular events like heart disease and stroke, compared with those who consumed four to five grams a day.

In people with high blood pressure, consuming more than seven grams a day increased the risk by 23 percent, but consuming less than three grams increased the risk by 34 percent, compared with those who ate four to five grams a day.

The lead author, Andrew Mente, an epidemiologist at McMaster University in Hamilton, Ontario, said that eating less salt does indeed lower blood pressure.

“But low sodium intake may be harmful,” he added. “It’s important not to rely on blood pressure alone, but rather to look at actual clinical events — heart attack, stroke, mortality.”