Sitting in front of the tube munching salty snacks may be bad for your brain-and not just because of the dubious quality of whatever TV shows youre watching. New Canadian research reports that older adults who combined high sodium consumption from dietary salt with low physical activity were at greater risk of cognitive decline.
That combination is whats noteworthy, comments Irwin H. Rosenberg, MD, editor of the Tufts Health & Nutrition Letter. He adds, Its not that salt is bad for your brain-its excess salt, especially if youre sedentary. The difference in cognitive decline between high- and low-sodium intake was seen only in the group with the least physical activity.
Alexandra Fiocco, PhD, of Ryerson University, and colleagues followed 1,262 healthy older men and women, ages 67 to 84. Researchers assessed their diet and levels of activity by initial questionnaires and their cognitive ability with a standardized test at the beginning and annually for three years. Those with sedentary lifestyles and highest salt intake were most likely to show cognitive decline.
While lower sodium intake is associated with reduced blood pressure and risk of heart disease, this is believed to be the first study to extend the benefits of a lower sodium diet to brain health in healthy older adults.
The results of our study showed that a diet high in sodium, combined with little exercise, was especially detrimental to the cognitive performance of older adults, says Fiocco. But the good news is that sedentary older adults showed no cognitive decline over the three years that we followed them if they had low sodium intake.
A high level was defined as more than 3,090 milligrams of sodium a day. Thats more than double the recommended intake of 1,500 milligrams daily for older Americans set by the 2010 federal Dietary Guidelines. But its less than the actual average in the typical American diet-about 3,400 milligrams, three-quarters of which comes not from the salt shaker but from processed foods.
The new studys findings are especially relevant, says senior study author Carol E. Greenwood, PhD, of the University of Toronto, as we know that munching on high-salt processed snacks when engaged in sedentary activities, such as watching TV or playing in front of the computer, is a frequent pastime for many adults.
TO LEARN MORE: Neurobiology of Aging, online first; abstract at dx.doi.org/10.1016/j.neurobiolaging. 2011.07.004.