Salty diet does harm in heart failure

People who've experienced heart failure and eat a high-salt diet are more likely to end up in the hospital, a new study finds.

"High salt intake is particularly dangerous for heart failure patients, even for those who are doing well and are stable on their medications," author Dr. Gary E. Newton of Mount Sinai Hospital in Ontario told Reuters Health.

In the study, people who ate an average of 3.8 grams of sodium per day -- equivalent to nearly 2 teaspoons of salt, and more than twice the maximum recommended by the American Heart Association for healthy people -- were twice as likely to be hospitalized for heart failure within a 3-year window as people who ate fewer salty foods.

Health experts generally suggest that people limit their salt intake, but the scientific evidence to support that recommendation for people with heart failure is generally "scant," Newton said.

The American Heart Association, for one, recommends that healthy people eat less than 1.5 grams of sodium per day. However, on average, Americans consume nearly 3.5 grams per day.

Sodium is dangerous in heart failure because it causes water to be retained in the body, which is already a problem in people with heart failure, who have fluid buildup in their lungs, abdomen, and ankles, Mary Knudson, co-author of "Living Well with Heart Failure," told Reuters Health in an e-mail. As a result, patients often take diuretics, which rid the body of excess fluid and sodium, and are advised to limit their salt intake, Knudson noted.

To investigate what effect a saltier diet might have on heart failure, Newton and his team followed 123 people with stable heart failure, the final stage of cardiovascular disease marked by shortness of breath, fatigue and swelling.

A small percentage of people with heart failure die each year, Newton explained, but many take medication and live with the condition, at which point it becomes chronic. Indeed, approximately 5 million Americans have been diagnosed with heart failure.

Among people with heart failure who ate an average of 3.8 grams of salt per day, nearly half were hospitalized for heart failure over an approximately 3-year period. In contrast, only 12 to 15 percent of the people with lower-salt diets - between 1.4 and 2.4 grams per day on average -- ended up in the hospital during the same time span.

People who ate the highest amounts of salt were also three times more likely to die during the study period, the authors report in the American Journal of Clinical Nutrition.

It's difficult to establish that the excess salt is to blame, Newton said in an interview. For instance, people who ate more salt may have been less healthy overall, eschewing exercise and not getting enough sleep, perhaps. "We don't have proof that it was the salt that was putting them in the hospital."

However, given the effect of salt on the cardiovascular system, it makes sense for people with heart failure to watch their salt intake, Newton added. The current study isn't large enough to establish exactly how much salt is too much, so the safest bet is to limit salt as much as possible, he noted.

Thankfully, people don't need to eat only bland food to avoid salt, Newton noted, because it's not the salt shaker that people have to worry most about. Rather, the bulk of sodium in our diet comes from restaurants and processed foods, such as cold cuts and other processed meats, Newton said.

Rather than hiding the salt shaker -- which would be largely "ineffectual" -- people should check the labels of every food product they buy, Newton said, since salt can sneak in everywhere from vegetable drinks to bread. Cooking more at home, and avoiding cheap restaurants, is another good step, the researcher added.

He also encouraged researchers to perform similar studies to investigate the effects of salt in people with other chronic health problems. "Every disease state really needs its own set of recommendations."

SOURCE: American Journal of Clinical Nutrition, online November 17, 2010.