The new data – published in Neurology– suggests that a diet lacking in omega-3 fatty acids could cause the brain to age faster and lose some of its memory and thinking abilities. The researchers, led by scientists at the University of California at Los Angeles (UCLA),USA, revealed that middle-aged and elderly adults who regularly consume foods rich in omega-3 fatty acids could slow the mental decline that leads to dementia – noting that those with the highest blood levels of DHA and EPA were more likely to perform well on tests of mental functioning and to experience less age-related brain shrinkage.
The authors said that whilst previous research linking dementia risk with the omega-3 fatty acids had looked at in blood plasma, which reflects how much people had eaten in the past few days, their current work estimated the amount of omega-3 participants had consumed over the last few months by looking at how much had built up in red blood cells.
"People with lower blood levels of omega-3 fatty acids had lower brain volumes that were equivalent to about two years of structural brain aging," explained study author Dr Zaldy Tan of UCLA.
In particular, Tan and his colleagues concluded that low DHA levels in red blood cells “are associated with smaller brain volumes and a ‘vascular’ pattern of cognitive impairment even in persons free of clinical dementia.”
In the new study, over 1,500 dementia free participants – with an average age of 67 – underwent MRI brain scans. The group were also tested to measure mental function, body mass, and the omega-3 fatty acid level in their red blood cells was sampled.
Tan and his colleagues found that people with DHA levels in the lowest 25% of the participants (the bottom quartile) had lower brain volume compared to people who had higher DHA levels. They said that the brain volume was enough to make people in the bottom quartile’s brains appear two years older than those of people in the top three-quarters.
The researchers added that participants with levels of all omega-3 fatty acids in the bottom quartile also scored lower on tests of visual memory and executive function, such as problem solving and multi-tasking and abstract thinking.
Brain scans also showed signs of less blood supply in the brains of people with the lowest omega-3 levels. Tan suggested that this may mean DHA plays a role in promoting general health of blood vessels in the brain in a similar way to how the omega-3’s are suggested to be aid heart health.
The new study adds further weight to previous research that suggests beneficial health effects of omega-3 fatty acids on the brain.
Last year Dr Rob Winwood of DSM Martek Biosciences explained to NutraIngredients how up to 15% of the brain by dry weight was made up of pure DHA. “One of the things we know is as you get older you lose DHA from the brain – so it would seem to make some sense that you might want to replace it,” he suggested.
Volume 78, Number 9, Pages 658-664, doi:10.1212/WNL.0b013e318249f6a9
“Red blood cell omega-3 fatty acid levels and markers of accelerated brain aging”
Authors: Z.S. Tan, W.S. Harris, A.S. Beiser, R. Au, J.J. Himali,et al