‘Bad’ fat bad for the brain
MedWire News: A high dietary intake of saturated fatty acid (SFA) may be associated with worsening cognitive function later in life, report researchers.
On the other hand, a high intake of monounsaturated fatty acid (MUFA) seems to be linked to improved cognitive aging, they say.
"When looking at changes in cognitive function, what we found is that the total amount of fat intake did not really matter, but the type of fat did," said lead author Olivia Okereke from Brigham and Women's Hospital, Boston, Massachusetts, USA) in a press statement.
As reported in the Annals of Neurology, Okereke and team analyzed data for a subset of older (>65 years) participants from the Women's Health Study (WHS), a randomized, placebo-controlled trial of aspirin and vitamin E supplements for prevention of heart disease and cancer.
Six thousand women completed cognitive function tests by telephone interviews, which were held in 1998 and again in 2000 and 2002, giving an average testing span of 4 years. The Telephone Interviews for Cognitive Status (TICS) was used to examine general cognitive function while the East Boston Telephone Memory Test was used to assess verbal memory.
Category fluency was evaluated by asking the participants to name as many animals as they could in 1 minute. The women's "global" cognition was estimated by averaging scores for the different cognition tests.
All of the women had already completed a 131-item food frequency questionnaire 5 years previously, on recruitment, and this was used in the current study to categorize the women into quintiles by SFA, MUFA, and polyunsaturated fatty acid (PUFA) intake, for regression analysis.
The study revealed that lower SFA and higher MUFA intakes were significantly associated with more favorable global cognition and verbal memory scores over time.
Linear trends of time by interaction with fat quintile showed significantly worse trajectories for global cognition score and verbal memory score with a higher versus lower SFA fat intake.
In addition, women in the highest versus lowest quintile for SFA intake were 60−70% more likely to have the worst change in cognitive performance (defined as the bottom 10% of the distributions of the global or verbal memory change scores) over the 4-year period.
By contrast, those in the highest versus lowest quintile for MUFA intake were 40−50% less likely to have the worst change in cognitive performance.
Total fat, PUFA and trans fat intakes were not associated with cognitive trajectory, says the team.
"Our findings have significant public health implications," said Okereke. "Substituting the good fat in place of the bad fat is a fairly simple dietary modification that could help decline in memory."
"Dietary patterns that incorporate higher intake of good fats (eg, the Mediterranean diet) should be further addressed in cognitive aging research," conclude Okereke et al.
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By Sally Robertson