High salt intake risky in people with heart disease

Americans’ salt intake is a major issue among health experts, with controversy lingering over how much salt is too much. A new study suggests that clarification on this question is sorely needed, especially for people with existing heart disease.

The study looked at sodium excretion in the urine -- which is a measure for sodium intake in one’s diet -- of 28,800 adults who were at high risk for heart disease or diabetes or who had heart disease. Sodium and potassium excretion were measured for 24 hours, which was an advantage in this study compared to others that have tried to determine the impact of dietary salt on health.

The researchers, from McMaster University in Hamilton, Ontario, Canada, then analyzed the participants’ cardiovascular problems and deaths four to five years later.

After controlling for other factors associated with cardiovascular problems, they found that higher sodium excretion (more than 7.0 grams per day) was linked to an increased risk of stroke, heart attack and cardiovascular death compared to moderate sodium excretion of 4.0 to 5.9 grams per day.

In addition, low excretion -- less than 3.0 grams per day -- corresponded to an increased risk of cardiovascular death. Low sodium excretion is often linked to conditions that involve fluid retention.

Higher potassium excretion was associated with a reduced risk of stroke. Earlier studies indicate that the ratio of sodium-to-potassium intake, rather than sodium alone, is thought to be an important influence on health outcomes.

Dietary guidelines recommend a sodium intake of no more than 1,500 milligrams (1.5 grams) per day for most adults. But the majority of people consume about 2,300 milligrams per day, according to studies.

More research is needed to refine guidelines for sodium and potassium intake, said the authors of an editorial accompanying the study. But, they wrote, most salt intake comes from processed foods, and that those foods should be avoided. “This shift to a more natural diet would concurrently lead to an absolute increase in dietary potassium content and also lead to an improved sodium-potassium ratio, which may be more desirable than a change of either electrolyte [salt or potassium] on its own.”

The study was published Tuesday in the Journal of the American Medical Assn.

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