Four months of supplementation with 2.5 grams or 1.25 grams of omega-3s led to decreases in levels of pro-inflammatory cytokine interleukin-6 (IL-6) of 10 and 12%, respectively, compared with a 36% increase in the placebo group.
Chronic inflammation is brought about by an over-expression or lack of control of the normal protective mechanisms, and it has been linked to a range of conditions linked to heart disease, osteoporosis, cognitive decline and Alzheimer's, type-2 diabetes, and arthritis.
“Our data suggest that n-3 PUFAs can reduce inflammation in overweight, sedentary middle-aged and older adults, and thus could have broad health benefits,” wrote researchers from Ohio State University in Brain, Behavior and Immunity.
“Although the n-3 PUFAs cannot take the place of good health behaviors like exercise, individuals who are at risk because of established inflammatory diseases or conditions may profit from their use.
“These data provide a window into the ways in which the n-3 PUFAs may impact disease initiation, progression, and resolution.”
However, Harry Rice, PhD, VP of regulatory and scientific affairs for GOED, the omega-3 trade association, questioned the conclusions of the researchers.
"While there is little doubt in my mind that the long-chain O-3s are anti-inflammatory, I question whether the present research advances our knowledge or understanding of the topic.
"Specifically, I'm concerned that the results from this small, 4-month supplementation trial, that took 4 1/2 years to conduct, were inflated because the placebo increased both TNF-alpha and IL-6? Unfortunately, the authors did not address this in the discussion," said Dr Rice.
The Ohio State researchers, led by Professor Jan Kiecolt-Glaser, recruited 138 adults with an average age of 51. Ninety-one percent of the participants were overweight and 47% were obese. They were randomly assigned to receive placebo or 1.25 or 2.5 grams per day of omega-3
The daily doses of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were 868.75 milligrams and 145mg, respectively, in the low-dose group, and 2085 mg and 348 mg, respectively, in the high-dose group.
“We chose the 7:1 EPA/DHA balance because of evidence that EPA has relatively stronger anti-inflammatory and antidepressant effects than DHA,” explained Kiecolt-Glaser and her co-workers.
After four months of supplementation, results indicated significant reductions in IL-6 levels, compared with placebo.
Levels of the cytokine tumor necrosis factor-alpha (TNF-alpha) also decreased by 0.2% and 2.3% in the low- and high-dose groups, respectively. The placebo group's TNF-alpha increased by an average of 12%.
"This is the first study to show that omega-3 supplementation leads to changes in inflammatory markers in the blood in overweight but otherwise healthy people. In terms of regulating inflammation when people are already healthy, this is an important study, in that it suggests one way to keep them healthy,” said Kiecolt-Glaser.
The researchers also sought to determine whether omega-3 fatty acids could reduce depression symptoms, but participants had relatively few symptoms to begin with so no significant reductions were seen.
The study was supported by grants from the National Institutes of Health (NIH). The supplements were supplied by OmegaBrite, a company based in Waltham, Mass.
Source: Brain, Behavior, and Immunity
Published online ahead of print, doi: 10.1016/j.bbi.2012.05.011
“Omega-3 supplementation lowers inflammation in healthy middle-aged and older adults: A randomized controlled trial”
Authors: J.K. Kiecolt-Glaser, M.A. Belury, R. Andridge, W.B. Malarkey, B. Seuk Hwang, R. Glaser