From Our 2009 Archives
DASH Diet Combats Mental Decline
Low-Fat, High-Fiber Diet Curbs Memory Loss
Reviewed By Louise Chang, MD
Known as the Dietary Approaches to Stop Hypertension (DASH) diet, the plan emphasizes fruits and vegetables, nuts and legumes, whole grains, and low-fat dairy products. Sodium, sweets, and red meats are to be consumed sparingly.
In a new study, the greater a person's adherence to the DASH diet, the slower the rate of mental decline, reports Heidi Wengreen, PhD, RD, assistant professor of nutrition at Utah State University in Logan, and colleagues.
It's not surprising that the diet worked: The DASH eating plan has been proven to lower blood pressure, and high blood pressure is a known risk factor for Alzheimer's disease and dementia, says Ron Munger, PhD, a professor of nutrition at Utah State who also worked on the study.
"Over the years, researchers have tried to slow cognitive decline using single nutrients and supplements, with mixed results. [That's because] the total diet is greater than the sum of its parts," he tells WebMD.
Vegetables, Nuts, Whole Grains Help
The study involved 3,831 people 65 and older with no signs of dementia.
At the start of the study, they filled out a 142-item food questionnaire asking what they ate and how often they ate it. Based on their adherence to the components of the DASH diet, the participants were divided into five groups, or quintiles.
A standard test that measures overall cognitive function, including memory, attention span, and problem solving, was given at the outset and four other times over an 11-year period.
The researchers found that those in the highest quintile had the best cognitive functioning at the beginning of the study and the least decline in mental skills over time.
The best foods at curbing mental decline: vegetables, whole grains, low-fat dairy products, and nuts and legumes, Munger says.
The findings were presented at the Alzheimer's Association 2009 International Conference on Alzheimer's Disease.
Not Easy to Follow
The DASH diet isn't easy to follow, he acknowledges. It calls for a total of eight to 10 servings of fruits and vegetables a day, for example, and "only about 25% of Americans eat even five servings a day," Munger says.
"The good news is there's lots of room for improvement," he says.
Also, the study doesn't prove that the diet slows mental decline. It could be the diet itself or some other lifestyle factor shared by people who eat well that is responsible for the protective effect.
On the other hand, DASH is proven safe and effective and lowers blood pressure, so there's no reason not to follow it, Munger says.
Each day that you follow the eating plan "helps you to preserve a little bit of cognitive function that otherwise would have been lost," says Maria Carrillo, PhD, director of medical and scientific relations at the Alzheimer's Association.
"And it's cumulative, so ultimately there's a big difference," she tells WebMD.
SOURCES: Alzheimer's Association 2009 International Conference on Alzheimer's Disease, Vienna, Austria, July 11-16, 2009. Heidi Wengreen, PhD, RD, assistant professor of nutrition, Utah State University, Logan. Ron Munger, PhD, professor of nutrition, Utah State University, Logan. Maria Carrillo, PhD, director of medical and scientific relations, Alzheimer's Association, Chicago.
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