[Note: to read the full text of this report on a trial finding that fish oil supplementation was reducing salivary cortisol & swapping fat body mass for lean mass, click here.]
Background: To determine the effects of supplemental fish oil (FO) on resting metabolic rate (RMR), body composition, and cortisol production in healthy adults.
Methods: A total of 44 men and women (34 ± 13y, mean+SD) participated in the study. All testing was performed first thing in the morning following an overnight fast. Baseline measurements of RMR were measured using indirect calorimetry using a facemask, and body composition was measured using air displacement plethysmography. Saliva was collected via passive drool and analyzed for cortisol concentration using ELISA.
Following baseline testing, subjects were randomly assigned in a double blind manner to one of two groups: 4 g/d of Safflower Oil (SO); or 4 g/d of Fish Oil (FO) supplying 1,600 mg/d eicosapentaenoic acid (EPA) and 800 mg/d docosahexaenoic acid (DHA).
All tests were repeated following 6 wk of treatment. Pre to post differences were analyzed using a treatment X time repeated measures ANOVA, and correlations were analyzed using Pearson's r.
Results: Compared to the Safflower Oil group, there was:
• A significant increase in fat free mass following treatment with Fish Oil (FO = +0.5 ± 0.5 kg, SO = -0.1 ± 1.2 kg, p = 0.03), a significant reduction in fat mass (FO = -0.5 ± 1.3 kg, SO = +0.2 ± 1.2 kg, p = 0.04),
• And a tendency for a decrease in body fat percentage (FO = -0.4 ± 1.3% body fat, SO = +0. 3 ± 1.5% body fat, p = 0.08).
• No significant differences were observed for body mass (FO = 0.0 ± 0.9 kg, SO = +0.2 ± 0.8 kg), RMR (FO = +17 ± 260 kcal, SO = -62 ± 184 kcal) or respiratory exchange ratio (FO = -0.02 ± 0.09, SO = +0.02 ± 0.05).
• There was a tendency for salivary cortisol to decrease in the FO group (FO = -0.064 ± 0.142 ?g/dL, SO = +0.016 ± 0.272 ?g/dL, p = 0.11).
• There was a significant correlation in the FO group between change in cortisol and change in fat free mass (r = -0.504, p = 0.02) and fat mass (r = 0.661, p = 0.001).
Conclusion: 6 wk of supplementation with FO significantly increased lean mass and decreased fat mass. These changes were significantly correlated
Source: Journal of the International Society of Sports Nutrition, Oct 8, 2010;7:31. PMID: 20932294, by Noreen EE, Sass MJ, Crowe ML, Pabon VA, Brandauer J, Averill LK. Department of Health Sciences, Gettysburg College, Gettysburg Pennsylvania, USA. [Email: firstname.lastname@example.org]