By Craig Weatherby
Human brains consist largely of fat, and the most abundant fat is omega-3 DHA … which, along with EPA, is one of the two major omega-3s in seafood.
We need DHA and EPA to survive and thrive. While people can make both from the plant-source omega-3 called ALA, our bodies convert a mere one to 10 percent into DHA and EPA.
The idea that omega-3 DHA from seafood is essential to key brain functions and helps optimize brain health enjoys ample evidence.
Does dietary DHA enhance seniors' brain health?
Most of several epidemiological studies – and all of the few brain-scan studies – indicate that diets higher in omega-3s or fish aid brain health and reduce the risk of Alzheimer's.
But the most recent evidence review found no clear proof that omega-3 supplements aid brain function in cognitively healthy older people (Sydenham et al. 2012).
To date, only two randomized, controlled trials have measured the effect of omega-3 supplements on cognitive function in older, healthy people.
Of these trials, only one found a benefit, in the subgroup carrying a variant of the ApoE gene that's linked to a much higher risk for cardiovascular disease and Alzheimer's (ApoE-ε4).
What about younger brains?
There's been some skepticism that increased DHA intake from fish or pills could yield cognitive benefits in younger healthy adults.
Now, UK scientists report the results of a similar trial, with similarly positive outcomes (Stonehouse W et al. 2013).
Few Americans consume enough omega-3s, and most consume far too many omega-6s from vegetable oils, which compete for space in our cell membranes.
If the new findings prompt more people to take healthy daily doses of fish oil, that could yield broad, substantial societal and personal benefits.
UK clinical trial affirms omega-3 DHA benefits for young and middle-aged brains
Scientists from the UK's University of East Anglia and Northumbria University recruited 176 healthy adults aged between 18 and 45 for a well-designed trial (randomized, placebo-controlled, double-blind).
The volunteers' diets were relatively low in DHA, so the results may not apply to people who routinely consume ample amounts.
(Global health agencies recommend getting 250-500mg of omega-3s daily from fish or supplements, with about half, or 125-250mg, being DHA … to put this in perspective, see our Seafood Nutrition Chart
. For more info on omega-3 intake advice, see our Omega-3 Facts & Sources
The participants were randomly assigned to take either omega-3 DHA supplements (1.16 grams DHA per day) or placebo capsules, for six months.
Before and after the trial period, they took a series of computer tests to check for any changes in seven key measures of brain function: episodic memory, working memory, attention, reaction times for episodic and working memory, and processing speed.
Compared with the placebo group, the entire DHA group showed improvements in two areas:
There were some gender-specific variations in the outcomes:
For example, working memory reaction times for men in the DHA group dropped by a robust 20 percent, compared with men in the placebo group (0.2 seconds faster than before the trial).
As the authors wrote, “These memory-related cognitive domains are the building blocks of more-complex cognitive functions or behaviors that are common in everyday life. Thus, young healthy adults may cognitively benefit from an increased consumption of DHA.” (Stonehouse W et al. 2013)
Gene-related differences seen
The UK team also examined the influence of a person's ApoE genotype in particular.
No link was detected between the volunteers' ApoE-variant profile and their cognitive performance.
However, while all the men benefited from DHA in terms of attention and working memory reaction times, the effects were considerably greater in the ApoE4-variant carriers.
We surely do need more controlled trials to detail the effects of DHA in people or varying gender, ethnicity, age, and diet pattern (e.g., habitual omega-3 and omega-6 intake).
As the UK group said, “More-robust randomized control trials that … take into account the habitual intake of long chain omega-3s [DHA and EPA] are needed to confirm the findings of this study …” (Stonehouse W et al. 2013).
But it's already clear that getting ample amounts of omega-3 DHA is a smart brain insurance policy.
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