Post by theshee on Apr 24, 2010 23:33:03 GMT 10
Claims that fish oil supplements preserve cognition should not be swallowed hook, line, and sinker, researchers said.
In a randomized, placebo-controlled trial of nearly 900 septuagenarians, the omega-3 fatty acid supplements had no effect on cognition, according to Alan Dangour, PhD, of the London School of Hygiene and Tropical Medicine, and colleagues.
Over a two-year period, there was no difference in cognitive decline in either the fish oil or placebo arm of the study, the longest yet conducted, Dangour and colleagues said online in the American Journal of Clinical Nutrition.
"There is no evidence of an important benefit for memory or concentration," Dangour said in a statement.
Still, he cautioned that cognitive function can take years to decline, "and although this is the longest trial of its kind ever conducted, it may be that it was not long enough for any true beneficial effects to be detected among this healthy cohort of older people."
The findings come from the so-called OPAL study (for Older People And omega-3 Long-chain polyunsaturated fatty acids), which enrolled 876 healthy and cognitively sound people in Britain, ages 70 through 79.
They were randomized to get either an olive oil placebo or the combination of 200 milligrams of eicosapentaenoic acid and 500 milligrams of docosahexaenoic acid daily for two years.
Eicosapentaenoic and docosahexaenoic acid are omega-3 long-chain polyunsaturated fatty acids, commonly found in oily fish. They have been associated with cognitive benefits in observational studies, but there was no evidence of a positive effect in a recent six-month randomized trial, the researchers said.
"Current evidence of a benefit for cognitive health is not convincing," the researchers said.
In the current study, participants were tested on a range of cognitive tasks at the beginning of the trial and after 24 months, the researchers said.
The primary outcome was recall of a 16-word list from the California Verbal Learning Test, but the researchers also tested immediate and delayed recall, spatial memory, processing speed, reaction time, and executive function, among other things.
After 24 months, Dangour and colleagues found, participants getting the fish oils had more of them in their blood (at P<0.001 for both comparisons) than did those in the placebo arm.
At the same time, placebo participants had higher serum concentrations of two omega-6 fatty acids as well as two components of olive oil.
But there were no significant differences between the groups on the California Verbal Learning Test, they researchers said.
After adjustment for baseline cognitive function, age, sex, and age at leaving full-time education, the average difference between the fish oil and placebo arms in the total number of words recalled over three trials in the California Verbal Learning Test was minus 0.5 words.
The average difference in recall after a 20-minute delay was 0.1 words.
There was also no significant difference in any of the other cognitive function tests, the researchers said.
Adverse events were minor -- typically annoyances as flatulence, belching, abdominal discomfort, and loose stools -- and were not significantly different between the groups, the researchers found.
The study had support from the UK Food Standards Agency and UK National Health Service Research and Development. The authors did not report any conflicts.
Primary source: American Journal of Clinical Nutrition
Source reference:
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 trial1-3" Am J Clin Nutr 2010; DOI: 10.3945/ajcn.2009.29121.
In a randomized, placebo-controlled trial of nearly 900 septuagenarians, the omega-3 fatty acid supplements had no effect on cognition, according to Alan Dangour, PhD, of the London School of Hygiene and Tropical Medicine, and colleagues.
Over a two-year period, there was no difference in cognitive decline in either the fish oil or placebo arm of the study, the longest yet conducted, Dangour and colleagues said online in the American Journal of Clinical Nutrition.
"There is no evidence of an important benefit for memory or concentration," Dangour said in a statement.
Still, he cautioned that cognitive function can take years to decline, "and although this is the longest trial of its kind ever conducted, it may be that it was not long enough for any true beneficial effects to be detected among this healthy cohort of older people."
The findings come from the so-called OPAL study (for Older People And omega-3 Long-chain polyunsaturated fatty acids), which enrolled 876 healthy and cognitively sound people in Britain, ages 70 through 79.
They were randomized to get either an olive oil placebo or the combination of 200 milligrams of eicosapentaenoic acid and 500 milligrams of docosahexaenoic acid daily for two years.
Eicosapentaenoic and docosahexaenoic acid are omega-3 long-chain polyunsaturated fatty acids, commonly found in oily fish. They have been associated with cognitive benefits in observational studies, but there was no evidence of a positive effect in a recent six-month randomized trial, the researchers said.
"Current evidence of a benefit for cognitive health is not convincing," the researchers said.
In the current study, participants were tested on a range of cognitive tasks at the beginning of the trial and after 24 months, the researchers said.
The primary outcome was recall of a 16-word list from the California Verbal Learning Test, but the researchers also tested immediate and delayed recall, spatial memory, processing speed, reaction time, and executive function, among other things.
After 24 months, Dangour and colleagues found, participants getting the fish oils had more of them in their blood (at P<0.001 for both comparisons) than did those in the placebo arm.
At the same time, placebo participants had higher serum concentrations of two omega-6 fatty acids as well as two components of olive oil.
But there were no significant differences between the groups on the California Verbal Learning Test, they researchers said.
After adjustment for baseline cognitive function, age, sex, and age at leaving full-time education, the average difference between the fish oil and placebo arms in the total number of words recalled over three trials in the California Verbal Learning Test was minus 0.5 words.
The average difference in recall after a 20-minute delay was 0.1 words.
There was also no significant difference in any of the other cognitive function tests, the researchers said.
Adverse events were minor -- typically annoyances as flatulence, belching, abdominal discomfort, and loose stools -- and were not significantly different between the groups, the researchers found.
The study had support from the UK Food Standards Agency and UK National Health Service Research and Development. The authors did not report any conflicts.
Primary source: American Journal of Clinical Nutrition
Source reference:
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 trial1-3" Am J Clin Nutr 2010; DOI: 10.3945/ajcn.2009.29121.