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Supplementation of omega−3 with mostly EPA (but not mostly DHA) improves cognitive function


The brain is composed of a significant amount of fat, a large proportion of which consists of the long-chain omega−3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Therefore, it has been suggested that intake of EPA and DHA may improve brain function. This study examined whether omega−3 supplements containing mostly EPA and mostly DHA vary in their effects on cognition.

The study

In this 26-week randomized controlled trial, 310 healthy adults (aged 25–49) with a low intake of oily fish were assigned to take capsules containing one of the following:

  • 900 mg DHA and 270 mg EPA (DHA group)

  • 360 mg DHA and 900 mg EPA (EPA group)

  • Refined olive oil (placebo group)

Both omega-3 supplements were in the form of ethyl esters and were formulated to spontaneously form microemulsions in the stomach for increased absorption when taken without food.

The study participants underwent a battery of cognitive tests that lasted approximately 1 hour. The data from the tests were used to assess cognitive function. The participants also reported their subjective mental fatigue and mood.

An additional study of overnight memory consolidation, which took place over 13 weeks, was conducted in a subsample of 155 participants.

The results

Supplementation with EPA led to improved accuracy on the cognitive tests compared with both the DHA and the placebo groups, improved accuracy of memory compared with the DHA group, and improved speed compared with the placebo group. There were no differences between groups on mental fatigue or mood.

In the substudy of memory consolidation, DHA led to faster reaction time compared with the placebo. There were no other differences between groups.

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