There is an expansive body of science backing the potential human brain benefits of both fish oil’s fatty acids and blueberry’s anthocyanin—a family of compounds that give fruits their red, purple, or blue hues, argued researchers from the Department of Psychiatry & Behavioral Neuroscience at the University of Cincinnati Academic Health Center.
Hence, they wanted to see if there were any significant improvements when study participants consumed both fish oil and blueberry supplements. But at the end of the trial they concluded, “combined fish oil and blueberry therapy was not associated with cognitive or functional enhancement.”
The conclusion does not discount the positive effects seen among study participants assigned to either just the fish oil supplement group or just the dried blueberry group.
“Enhancement of perceived functional capability suggests that fish oil-treated and blueberry-treated participants experienced meaningful improvement of cognitive capability, a notable finding, given that subjective cognitive complaints were an inclusion criterion for study participation,” they reported.
Their report was published in the April issue of Neurobiology of Aging. Researchers from the Cincinnati Children’s Hospital Medical Center and the Kentville Research and Development Centre in Nova Scotia, Canada, were also part of the study.
The National Institute of Health provided a grant to complete the study. Lead researchers in the study, Robert K. McNamara and Robert Krikorian, both affiliated with the University of Cincinnati, have received funding from nutraceutical and ingredient companies before, such as DSM Nutritional Products. They declared no conflict of interest.
Study design
This was a randomized, double-blind, parallel groups, placebo-controlled trial. Researchers recruited participants aged 62 to 80 from the Cincinnati, OH area who had mild, self-perceived cognitive decline with aging.
They did not include applicants who had a diagnosed cognitive impairment (like dementia) or have already taken medication or supplements to aid their cognitive health.
A total of 76 participants completed the study, randomly divided into the following groups: Fish oil (17 participants), blueberry (19), blueberry and fish oil (20), or placebo (20). The total study period lasted 24 weeks.
Supplementation and analyses
The fish oil capsules were provided by the Inflammation Research Foundation based in Massachusetts. Each contained 400-mg EPA and 200-mg DHA. Participants were instructed to take two capsules with breakfast and two with dinner. The placebo fish oil capsule was filled with corn oil.
The blueberry powder was made of freeze-dried and powdered blueberries provided by the US Highbush Blueberry Council in California and the Wild Blueberry Association of North America in Maine. The placebo was a proprietary mixture provided by the US Highbush Blueberry Council, made as similar as possible with a different nutrient profile (for example, fiber was not included in the placebo).
Participants were instructed to take a dose equivalent to a cup of blueberries a day, a dose based on previous studies on the fruit’s cognitive benefits. In addition, participants were asked to limit and document the consumption of other anthocyanin-rich fruits and seafood in their daily diets.
Participants visited the lab to take cognitive performance questionnaires, urine tests for anthocyanin levels, and red blood cell tests for fatty acid profile.
‘Surprising’ results
The researchers found that the EPA and DHA composition increased in the fish oil groups, while total urinary anthocyanin metabolites did not differ between the groups.
However, they did find that urinary levels of glycoside and native food forms increased only in the blueberry-supplemented groups.
From the cognitive test results, the researchers learned that two groups—fish oil with blueberry placebo group and the blueberry with fish oil placebo group–each reported fewer cognitive symptoms. The blueberry group showed improved memory discrimination, leading the researchers to conclude that “supplementation improved cognition.”
“These effects are of interest in the context of a sample of cognitively unimpaired older adults with subjective cognitive complaints and indicate that meaningful cognitive benefit contributed to improved functional capability,” the authors argued.
They added that the absence of a beneficial effect of the two ingredients combined is “surprising.”’
“Particularly in the context of benefit associated with each of the individual treatments,” they wrote. “It is unclear what factors might have contributed to this lack of effect, although one consideration is that daily, long-term supplementation with the combined treatments may have subverted a beneficial response in some way.”
Source: Neurobiology of Aging
Published online ahead of print, https://doi.org/10.1016/j.neurobiolaging.2017.12.003
Cognitive response to fish oil, blueberry, and combined supplementation in older adults with subjective cognitive impairment
Authors: Robert K. McNamara, et al.