Sioux Falls, SD—Alzheimer’s patients may need higher omega-3 intakes to see benefits than previously thought, according to a study published inThe Lancet.

The study looked at 33 men and women from Los Angeles aged 55 and older who had a family history of Alzheimer’s disease, although they didn’t have it themselves, according to a press release on the topic. They had generally sedentary lifestyles, ate little to no fatty fish, and hadn’t taken omega-3 capsules for at least three months prior to the study. 15 of the participants carry the APOE4 gene, which is linked to inflammation in the brain and known to increase Alzheimer’s risk by a factor of four or more.

The treatment group was required to take 2,152mg of DHA for six months, and were instructed to otherwise limit their polyunsaturated fatty acid intake. The control group was given placebo capsules containing corn/soy oil. Both groups took daily vitamin B complex supplements, which help the body process omega-3s.

Participants were seen at screening, baseline, and at the end of the study six months in. Researchers looked for changes in plasma and cerebrospinal fluid (CSF) levels of DHA and EPA, and how those correlated with APOE status—E4 or not—and CSF levels of a biomarker of brain amyloid deposition. The researchers also performed cognitive function tests.

At the study’s conclusion, the treatment group had a 200% increase in blood plasma DHA levels compared with the placebo group—but DHA in the CSF only went up 28%. The percentage increase for DHA who didnotcarry a copy of the APOE4 gene tended to be higher than for those who were carriers. Those who did not carry the APOE4 gene variant also showed an increase of EPA in their CSF three times greater than that seen in the APOE4 carriers.
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The press release notes that previous clinical trials have had disappointing results when testing the direct effects of omega-3 supplementation on Alzheimer’s disease. The increase in DHA in the CSF in this study, while much lower than the increase in DHA in blood plasma, is higher than has been seen in any other trial, suggesting that 1 gram of omega-3s is not enough for preventative purposes; 2 grams, as used in this trial, is necessary.

Another takeaway: EPA levels went up, although only DHA was supplemented, suggesting that DHA can to some extent raise both DHA and EPA levels in the body.

William Harris, Ph.D., Founder and CEO of OmegaQuant, explained in the press release that the low increase in CSF DHA is caused by the blood-brain barrier, which only allows certain compounds in, and makes it harder for some nutrients to reach the brain. “Therefore, future research should strongly consider whether a dose of 2 grams daily of omega-3 is enough to find benefit for a disease like AD or whether even higher doses should be administered,” Dr. Harris said. “This may be  especially true for those who have known risk factors for AD, such as carrying the APOE4 gene variant. It appears that these people may be less able to transfer DHA from the blood to the brain than those who don’t carry the gene.”

Researchers plan to repeat the study on 300 participants over a two-year period to test these “intriguing” results, according to the press release.