Omega-3 and cognition
2 papers in the library, strongest Moderate.
Graded Moderate · Chance assigned 360 older adults to four groups, including a dummy pill, for a full year; but everyone came from a single district in China.
Papers 2
- Vitamin D Plus Omega-3 Lifted Thinking Scores Over a YearModeraten = 3602026NutrientsOlder adults with mild cognitive impairment, meaning a noticeable dip in thinking skills, scored better on intelligence tests after a year of vitamin D and the omega-3 fat DHA. The gain was largest when people took both together. Each one on its own also did better than a dummy pill. The trial ran in Tianjin, China, with 360 people aged 65 or older who lived at home. They were split at random into four groups: 800 units of vitamin D3 a day, 1 gram of DHA, both, or capsules of corn oil. In total, 355 stayed to the end. After twelve months, the combined group's overall test score was almost 13 points higher than the dummy group's. Certain inflammation markers in the blood fell in all three active groups. No side effects were reported. The researchers suspect a protein called gasdermin D plays a part, as it is involved in an inflammatory form of cell death. By their calculation, though, its drop explained only about 8 percent of the effect. All participants came from one district, and diet and exercise were not fully accounted for. Whether the results hold elsewhere is still open.
- DHA Reaches the Brain but Brings No Edge in Thinking TestsModeraten = 3652026EBioMedicineA daily two grams of the omega-3 fat DHA does reach the nervous system. Researchers saw it in spinal fluid, the liquid that surrounds the brain and spinal cord. After six months, the ratio of DHA to another fatty acid there had risen. Yet after two years, people scored no better on thinking tests than those on a dummy pill. Brain volume showed no clear difference either. The trial ran at the University of Southern California with 365 people aged 55 to 80. None had dementia. All ate little DHA and had at least one dementia risk factor. They were chosen at random to take DHA capsules or look-alike capsules of corn and soybean oil. Almost half carried APOE ε4, a gene variant that raises Alzheimer's risk. In them, DHA reached the spinal fluid just as well. The trial has limits. Some 38 percent dropped out, mostly because of COVID-19. Participants were also fairly young, well educated and mentally sharp, which may hide small effects. The authors conclude that research should now focus on how the brain handles DHA rather than on more supplement trials.
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