June 16, 2006 -- Giving your salt shaker a makeover may trim your chances of dying of heart disease, high blood pressure, stroke, or diabetes.
That's what researchers in Taiwan found when they studied nearly 2,000 veterans at a retirement home in northern Taiwan.
The scientists included Hsing-Yi Chang, PhD, of Taiwan's National Health Research Institutes. They asked the retirement home's five kitchens to tinker with their recipes a bit for science's sake.
Specifically, Chang's team told two of the five kitchens to replace regular salt with potassium-enriched salt. The potassium-enriched salt swaps about half of regular salt's sodium for potassium.
For comparison, the three other kitchens used regular salt, without extra potassium. Other ingredients, including soy sauce (which is often high in sodium), weren't restricted.
Why focus on salt? While modest amounts of salt may be fine, high-sodium diets may lead to high blood pressure, a major heart disease risk factor. Potassium has been shown to lower blood pressure, Chang's team notes.
Who Ate What
For Chang's study to work, each veteran had to get all his food from the assigned kitchen. That way, the veteran only got potassium-enriched salt or regular salt. Grazing from kitchen to kitchen would muddy the data.
The test kitchens switched their salt gradually over a month. The veterans knew about the experiment, but they didn't know what type of salt was in their food.
A total of 768 veterans ate from the kitchens using potassium-enriched salt. Another 1,213 veterans got their food from kitchens using regular salt.
When the study started, most veterans were at least 65 years old. Their age, weight, and blood pressure were similar, with about 40% having high blood pressure. None was bedridden or had kidney problems. People with kidney problems should not take extra potassium in order to avoid problems such as abnormal heart rhythms.
Fewer Heart Deaths
The veterans were followed for 2.6 years, on average. During that time, 504 veterans died.
Chang's team found that a smaller proportion of veterans in the experimental group died of cardiovascular disease -- caused by high blood pressure, heart disease, heart failure, stroke, or diabetes-- than in the comparison group.
A total of 93 veterans died of cardiovascular disease. Of those veterans, 27 had gotten the potassium-enriched salt (29%); 66 had gotten regular salt (71%).
Deaths from other causes, including cancer and pneumonia, didn't differ between the groups. Medical expenses, especially for cardiovascular hospitalizations, were also lower in the group that had gotten potassium-enriched salt, the study shows.
The researchers checked the veterans' medical records for previous health problems. Adjusting for age and medical history didn't change the results.
Less Salt or More Potassium?
Chang's team isn't sure if the results were more influenced by slashing sodium or by pumping up potassium.
The researchers note that theirs is the first long-term study on the topic, but that their findings line up with results from short-term studies.
The study "showed the potential beneficial effects of potassium-enriched salt in the elderly, a great proportion of whom may be sodium-sensitive," write Chang and colleagues. It's not clear if the results apply to younger people.
The researchers call for more studies that include the general public and to "clarify whether the effect comes from lower sodium intake or from higher potassium intake."