Researchers from the University of Sheffield and Obsidian Research Ltd in the UK found that, while the DHA supplements did not statistically reduce body weight, compared to the control group receiving oleic acid-rich oil, the loss of body weight did “approach statistical significance”.
“Clinically relevant weight loss is 5% initial body weight, and in the present study, 39% of the subjects in the DHA group achieved this, compared with 7% in the [oleic acid-rich oil] group,” wrote the researchers in Nutrition Research .
“Although the between-treatment differences in those who achieved 5% initial body weight were not statistically significant, our results compare favorably with a clinically approved treatment (orlistat) for obesity, where 33% of subjects lost 5% initial bodyweight over a 1-year period.”
Charlotte Harden and her co-workers recruited 40 overweight and obese women to participate in their double-blinded, randomized, parallel study, with 27 women completing the full 12-weeks. The women were randomly assigned to receive 45% oil-in-water emulsions, containing predominantly DHA or oleic acid.
Results showed that women in the DHA group consumed significantly less energy, and fewer grams of carbohydrate and fat than the control group.
While no statistically significant differences were obtained for body mass and composition, there was trend toward significance in the DHA group, said the researchers.
Commenting on the potential mechanisms, Harden and her co-workers said that omega-3s may be acting on the expression of genes, with other studies reporting that the fatty acids may down-regulate the expression of genes involved in the growth of fat cells in fat tissue, as well as up-regulating gene expression for fatty acid oxidation.
DHA may also be modulating appetite by stimulating satiety hormones, they said, or via pathways to decrease the reward associated with food intake.
“Additional, longer-term, and adequately powered studies using subjects of both sexes are needed,” they wrote. “Other factors that should be considered include the following: the choice of n-3 PUFA–free emulsion, the BMI category of subjects, and ways of improving the compliancy and accuracy of dietary assessment.”
Source: Nutrition Research
Published online ahead of print, doi: 10.1016/j.nutres.2013.10.004
“Long-chain polyunsaturated fatty acid supplementation had no effect on body weight but reduced energy intake in overweight and obese women”
Authors: C.J. Harden, V.A. Dible, J.M. Russell, et al.