Older people who eat healthy, with more fruits and vegetables, nuts and fish in their diets, may be less likely to experience declines in thinking and memory over time, according to a new international study.
“It is likely that a healthy diet has effects on cardiovascular risk factors and cardiovascular disease, and that this is an important mechanism for reducing the risk of cognitive decline,” said lead author from McMaster University in Hamilton, Ontario, Canada, and the National University of Ireland in Galway.
Since the study was observational, the findings can only say that a healthy diet was associated with a reduced risk of cognitive decline; they cannot prove there is a causal relationship.
The researchers used data from two multinational randomized trials that included more than 27,000 men and women age 55 and older who had a history of coronary, cerebral or peripheral artery disease or high-risk diabetes and who were followed until death, stroke, heart attack or hospitalization. Half the participants were followed for less than five years.
Participants filled out a 20-point food frequency questionnaire at the beginning of the trials and completed a mini-mental state exam at least twice during their respective trials.
Of the 27,000 total participants, almost 17 percent experienced marked cognitive decline based on their mental state exams.
The researchers used the food frequency questionnaire to estimate how “healthy” people’s dietary habits were, awarding higher scores to frequent consumption of foods like vegetables, fruits, nuts, soy proteins and fish.
The top fifth of people with the healthiest diets were about 24 percent less likely to experience cognitive decline during the study than the bottom fifth with the worst diet scores.
Those with the healthiest diet tended to be more active, were less likely to smoke and had lower body mass index.
About 14 percent of people in the healthiest diet category had cognitive decline compared to 18 percent of those in the least-healthy category after taking physical activity, high blood pressure and cancer history into account.
All study participants were at high risk for cardiovascular disease, so the results may not be generalizable to the broader population.
Source: Neurology, online May 6, 2015.
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