Salt sensitivity: Sorting out the science

Eating too much salt usually boosts blood pressure, but not in everyone. Understanding the genetic basis of these differences may improve treatment of high blood pressure.

Do you know someone who eats lots of salty food — pizza, pickles, pretzels, and the like — but has naturally low blood pressure? That person may be salt-resistant, which means his or her blood pressure doesn't rise very much in response to a diet high in salt (sodium chloride). In contrast, other people are salt-sensitive, which means their blood pressure rises by 5 points or more if they switch from a low-sodium to a high-sodium diet.

Unfortunately, there isn't an easy test to determine who is salt-sensitive, says endocrinologist Dr. Gordon Williams, professor of medicine at Harvard Medical School. "Still, we know that Americans eat far more salt than they actually need, so it makes sense to advise everyone cut back on salt," he says.