Is Fish a Brain Food?

I’ve talked about the best brain-boosting fruits, nuts, spices, and vegetables. What about fish or fish oil for improving cognitive function? A review of dementia risk reduction strategies compiled a list of common attributes of purportedly brain healthy diets. People are encouraged to limit their intake of meat (including poultry), as well as fatty, sugary, and salty processed foods and consume a predominantly plant-based diet rich in fruits and vegetables (especially greens and berries), nuts, whole grains and legumes. But they also tend to encourage people to eat fatty fish.  
 
Recommendations for fish consumption are based on observational data finding, for example, a significantly lower risk of Alzheimer’s in fish eaters (though not necessarily dementia more broadly), a significantly lower risk of dementia in fish oil supplement takers (though not necessarily Alzheimer’s disease specifically), and greater hippocampal, or memory center volume, associated with higher levels of omega-3’s in the blood. Now fish eaters also tend to eat more vegetables and berries, smoke less, exercise more and have higher education levels than non-fish-eaters. And fish oil supplement takers also eat more fruits and vegetables, smoke less, and exercise more than those who don’t, and a also tend to have higher socioeconomic status. To see if the apparent benefits of aquatic omega-3’s from population studies are real and not just due to associated confounding factors, researchers have performed dozens of randomized controlled interventional trials to put it to the test. 
 
There have been three randomized, placebo-controlled trials of omega-3’s for Alzheimer’s disease over 6, 12, and 18 months and they unfortunately failed to show a cognitive benefit. Maybe it’s too late by then? What about preventing cognitive decline or dementia in the first place? The largest comprehensive review of long-chain omega-3s (from algae or fish) for cognitive outcomes (funded by the World Health Organization) found no significant protection from dementia or cognitive impairment and only “clinically unimportant” effects on global cognition. The reviewers conclude “People concerned about their cognitive health should be advised that taking long-chain omega-3 supplements is not helpful for cognition….”  
 
But is it possible there’s a threshold effect? Find out in my video Should We Take DHA Supplements to Boost Brain Function?