Fish Oil Again For The Win!

Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults

Eric E Noreen email, Michael J Sass email, Megan L Crowe email, Vanessa A Pabon email, Josef Brandauer email and Lindsay K Averill email

Journal of the International Society of Sports Nutrition 2010, 7:31doi:10.1186/1550-2783-7-31
Published: 8 October 2010
Abstract (provisional)

Background

To determine the effects of supplemental fish oil (FO) on resting metabolic rate (RMR), body composition, and cortisol production in healthy adults.

Method

S: 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: 4g/d of Safflower Oil (SO); or 4g/d of FO supplying 1,600mg/d eicosapentaenoic acid (EPA) and 800mg/d docosahexaenoic acid (DHA). All tests were repeated following 6wk 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 SO group, there was a significant increase in fat free mass following treatment with FO (FO= +0.5 +/- 0.5kg, SO= -0.1 +/- 1.2kg, p=0.03), a significant reduction in fat mass (FO= -0.5 +/- 1.3kg, SO= +0.2 +/- 1.2kg, 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 +/- 0.9kg, SO= +0.2 +/- 0.8kg), RMR (FO= +17 +/- 260kcal, SO= -62 +/- 184kcal) 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 +/- 0.142ug/dL, SO= +0.016 +/- 0.272ug/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: 6wk of supplementation with FO significantly increased lean mass and decreased fat mass. These changes were significantly correlated with a reduction in salivary cortisol following FO treatment.