We've all heard how too much salt is bad for our hearts -- associated with high blood pressure, heart attack and other health risks. But a new study shows it could be bad for our brain functioning, too.
The study looked at adults ages 67-84 years over the course of three years. Researchers found that those who consumed the most salt and didn't exercise did worse on tests on cognitive function than those who ate the least salt and exercised the most. The results are published in the journal Neurobiology of Aging.
"High" salt intake was defined as 3,090 milligrams, or just a bit more than a teaspoon of salt a day, which, for reference, is equivalent to that in three-and-a-half Big Mac burgers, the Daily Mail reported. However, some people in the study consumed three times that much salt in a day.
Fortunately, researchers also found that keeping salt intake to a minimum seems to be good for brainpower -- people in the study who ate the least salt didn't show any signs of cognitive decline, as indicated by their results on the tests, over the three-year study period.
The study shows that "you do have some control, and lifestyle is key" when it comes to protecting your brain as you age, study researcher Carol Greenwood, of the Baycrest Kunin-Lunenfeld Applied and Evaluative Research in Toronto, told ABC News.
The reason? Salt seems to have a negative effect on blood vessels, including the ones in our brains, researchers said. And other research shows that blood vessel damage seems to play a role in dementia.
Though a low-salt diet did seem to play a role in protecting against cognitive decline, physical activity was the main factor, ABC News reported. Even high salt consumers who reported high levels of physical activity were protected from cognitive decline over the study period, according to the study.
"It stands to reason that people who are more active, and fitter, and thus healthier overall, would better 'withstand' the potential harms of excess sodium than those lacking this immunizing benefit," Dr. David Katz, director of the Prevention Research Center at Yale University, told ABC News. However, Katz cautioned, the finding only finds an association -- not a causal relationship -- between salt and cognitive decline.
Recent news has also linked high salt consumption and low potassium consumption with a more than doubled risk of heart attack, compared with people who consume equal amounts of salt and potassium.
In addition to heart disease and cognitive decline, too much salt has also been linked to kidney disease and osteoporosis, said Dr. Joel Fuhrman, a HuffPost contributor and family physician who specializes in nutritional medicine.
Katz compiled a list of foods high in sodium that you might not expect. Check it out: