Clinical trial finds no brain benefit in people over 70, but even the authors took the results with a grain of salt; most evidence links higher omega-3 intake to better brain health
by Craig Weatherby
It’s easy to become confused by conflicting results from nutrition research.
For example, most people have the impression that omega-3s from fish enhance brain health and performance.
But the British authors of a new, two-year clinical trial found no evidence that fish oil improved the mental performance of healthy people aged 70 to 79.
- Two-year clinical trial found no difference between fish oil and placebo for brain performance in healthy people aged 70 to 79.
- The study authors said that two years may not be enough to detect any brain benefits among healthy people in this age range.
- The lack of any mental decline in the control group also suggests that the highly similar test group also had no significant mental decline for fish oil to reduce.
- Most but not all of the many epidemiological studies, and several clinical trials, link higher omega-3 intake to better brain health.
- There is ample lab and animal evidence that omega-3s affect the brain in ways that support cognition and memory.
A negative outcome in a trial testing fish oil in healthy older people is not exactly surprising, given that people’s brains decline slowly over many decades and cannot be expected to improve measurably in two years.
In fact, that’s just what the trial’s lead author, Dr. Alan Dangour, said in a press release:
“It is important to keep in mind that poor cognitive function can take many years to develop and although this is the longest trial of its kind ever conducted, it may be that it was not long enough for any beneficial effects to be detected among this healthy cohort [group] of older people” (LSHTM 2010).
And his team’s conclusion notes a key fact that makes the finding seem fairly insignificant… namely, that people in the control group showed no mental decline:
“The lack of decline in the control [placebo group] and the relatively short [study] period may have limited our ability to detect any potential beneficial effect of fish oil on cognitive function…” (Dangour AD et al. 2010).
Why does it matter that the control group showed no mental decline after two years?
The study design eliminated any significant differences between the healthy older people randomly assigned to take fish oil capsules and the healthy older people assigned to take placebo capsules (i.e., the control group).
Therefore, it seems safe to presume that there was no measurable mental decline in either group over the two-year study period… so it’s likely that there was no measurable mental decline for the omega-3s to reduce.
Some clinical trials and most epidemiological studies detect brain benefits
Importantly, other clinical trials have detected brain benefits in older people who’ve taken fish oil, as we reported in “Omega-3 Seen to Preserve Memory in Healthy People
,” “Omega-3s Boost Aging Brains in Clinical Trial
,” and “Fish Oil May Halt Memory Decline in Alzheimer's
The new trial’s negative findings are also contradicted by the positive indications obtained from most epidemiological studies, in which researchers look for links between various foods or food factors (such as omega-3s) and people’s brain health.
In fact, some of the same researchers behind today’s study published an epidemiological study last year that linked higher fish intake to better brain health (Albanese E et al. 2009).
To read some of our reports on positive epidemiological studies, see “Better Senior Brain Function Linked to Fish
,” “Brain Benefits of Fish (and Veggies) Gain Support
," and “Mental Decline Slowed by Omega-3s
While epidemiological studies cannot prove a cause-effect relationship between fish oil and brain performance, the sheer volume of positive evidence from such research seems to support the folks saying, “fish is brain food.”
And as we’ve reported, there’s ample laboratory evidence suggesting that omega-3s should work against age-related mental decline:
Let’s review the details of the study, which was authored by a team based at the London School of Hygiene and Tropical Medicine.
New trial detected no fish-oil benefit… but also saw no brain decline to deter
A British team led by Dr. Alan Dangour enrolled 867 participants aged 70-79 years for a two-year clinical trial designed to test the effects of fish oil on brain performance.
The trial participants all had good cognitive health at the start of the study, and were randomly assigned into two groups.
One group took fish oil capsules for two years, while the other group took placebo capsules (The fish oil capsules provided 200mg EPA and 500mg DHA per day, and the placebo pills contained olive oil).
The volunteers’ cognitive functions were assessed at the start and end of the study by trained research nurses, using a series of paper and pencil tests of memory and concentration.
After two years, the participants in the fish oil groups had significantly higher levels of omega-3 fatty acids in their blood than those participants receiving placebo capsules.
However, cognitive function did not change in either group, and there was no evidence that the consumption of omega-3s produced any benefit for cognitive function.
All in all, the bulk of evidence still supports the idea that gher-than-average omega-3 intake is good for brains at all stages of life.
- Albanese E, Dangour AD, Uauy R, Acosta D, Guerra M, Guerra SS, Huang Y, Jacob KS, de Rodriguez JL, Noriega LH, Salas A, Sosa AL, Sousa RM, Williams J, Ferri CP, Prince MJ. Dietary fish and meat intake and dementia in Latin America, China, and India: a 10/66 Dementia Research Group population-based study. Am J Clin Nutr. 2009 Aug;90(2):392-400. Epub 2009 Jun 24.
- Dangour AD et al. Effect of 2-y n–3 long-chain polyunsaturated fatty acid supplementation on cognitive function in older people: a randomized, double-blind, controlled trial. Published April 21, 2010; doi:10.3945/ajcn.2009.29121
- London School of Hygiene & Tropical Medicine (LSHTM). Fish oil supplements provide no benefit to brain power. April 21, 2010. Accessed at http://www.eurekalert.org/pub_releases/2010-04/lsoh-fos042110.php