Effects of Short Term Omega-3 Supplementation on Body Composition, Food Intake, and Lipid Proﬁle in Elite Athletes: A Double-Blind Randomized Controlled Trial

1. Abstract Previous studies consistently showed a key role for omega-3 fatty acids in decreasing fat mass (FM) in animal models. Also, increased omega-3 stimulates fat loss in individuals who experience obesity, diabetes and metabolic syndrome. However, it is not known whether omega-3 supplementation make similar effects in healthy individuals with low FM. This study aimed to investigate the effects of omega-3 on changes in body composition, food intake, and lipid proﬁle in healthy athletes. In this double-blind placebo-controlled RCT, 36 healthy athletes were allocated into omega-3 or placebo groups. Physical activity (global physical activity questionnaire), dietary intake (24-h food recall), anthropometric status, and lipid proﬁle were measured at baseline and after 3-weeks. 35 volunteers completed the trial. The weight did not signiﬁcantly change at the end of the study. Body fat% decreased signiﬁcantly HDL-C, and energy and protein intakes in athletes. Further studies are recommended to determine the effect of different doses of omega-3 on adipose tissue and blood lipids in athletes with low FM. Clinical Trial Registration: The present study was prospectively registered at the Iranian Registry of Clinical Studies on December 19, 2019 (ID: 20190625044008N1).


Abstract
Previous studies consistently showed a key role for omega-3 fatty acids in decreasing fat mass (FM) in animal models. Also, increased omega-3 stimulates fat loss in individuals who experience obesity, diabetes and metabolic syndrome. However, it is not known whether omega-3 supplementation make similar effects in healthy individuals with low FM.
This study aimed to investigate the effects of omega-3 on changes in body composition, food intake, and lipid profile in healthy athletes.
In this double-blind placebo-controlled RCT, 36 healthy athletes were allocated into omega-3 or placebo groups. Physical activity (global physical activity questionnaire), dietary intake (24-h food recall), anthropometric status, and lipid profile were measured at baseline and after 3-weeks. 35 volunteers completed the trial. The weight did not significantly change at the end of the study. Body fat% decreased significantly at the end of the study in the omega-3 group (p=0.003), but intergroup differences were not significant (p=0.77). FM decreased and fat free mass (FFM) increased in omega-3 groups (p<0.05). HDL-C increased (omega-3 group p=0.001; placebo group p=0.01; after adjustment for baseline values p=0.78). Also, in the omega-3 group, energy intake (p=0.0007) and protein intake (p=0.04) increased after intervention, but after baseline adjustments they were not significant.
In conclusion, 3-week omega-3 supplementation seems to be not effective in decreased FM, increased

Introduction
Nutritional supplements improve health indicators in the general population and especially in athletes.
According to the International Olympic Committee, athletes use dietary supplements for various reasons such as remain in good health, intake of specific nutrients that is beneficial for their sports, replacement of micro and macronutrient deficiencies, and provide the energy balance that might be difficult to achieve through food intake alone [1]. One of these nutritional supplements that widely used in recent years are omega-3 fatty acids that claimed to be useful for accelerate recovery, decreased appetite, change the expression of metabolic-related genes, increased muscle protein synthesis, and decreased fat mass (FM) [1][2][3].
Many studies showed nutrients have a direct effect on body composition [4][5][6][7]. As body fat percentage is a marker of health and it is determinant in athletic performance, measurement of the effect of nutrients on FM could be remarkable. As noted, one of these nutrients is omega-3 [8-10].
Omega-3s are essential nutrients for humans, that foods that should be yield from the diet or through supplementation [11][12][13][14][15][16]. It is recommended that adult's intake 500 mg per day of EPA and DHA by consuming 2 servings of fish per week [17]. Although fish consumption increased in recent decades, the intake of essential fatty acids from foods contributes to the provide a small amount of daily requires [18].
So, the American Heart Association recommends supplementation for adults not eating enough oily fish Omega-3 is beneficial for human health; regulate blood lipids, increased cognition, improve immunity, and neuromuscular function [19][20]. Although some animal studies found omega-3 intake through the diet may reduce body weight, body fat accumulation, and particularly visceral fat, the effectiveness of omega-3 supplementation as a complementary method in weight loss is not definitive [5,21,22]. Also, previous human studies showed in obesity, diabetes, metabolic syndrome, and some cancers omega-3 could alter body composition [5,23]. On the other hand, omega-3 enhanced the expression of metabolism related genes such as PPAR gamma that enhanced fat oxidation [24,25]. Some studies demonstrated as omega-3 increased appetite and food intake, so it could increase weight. Though weight increased; fat storage decreased and fat free-mass (FFM) increased.
Results in healthy adults are contradictory [3,26]. The studies suggest omega-3 is more effective in weight gain rather than weight loss, had different Placebo and supplements must be similar in terms of color, shape, and size. Gelatin capsule supplements and placebo will be stored at room temperature.
Therefore, subjects and investigators will not be known for the treatment assignments in the study.
Participants and researchers were all blinded to participant group members throughout the study.
Subjects assigned to the omega-3 (n=18) and placebo 2) The omega-3 group with low and moderate MET receiving supplements of omega-3.
3) The placebo group with high MET receiving placebo two soft gel capsules per day, each capsule containing one g of edible paraffin oil; provided by Zahravi Pharmaceutical, Co., Tabriz, Iran.
4) The placebo group with low and moderate MET receiving paraffin soft gel capsules.

Intervention
All the participants received supplements or a placebo for three weeks. All participants were asked to take

Results
Of the 373 valentines who were screened by phone, 57 met all inclusion/exclusion criteria. However, after a face to face meeting, 21 were excluded due to a BMI>30 (n=11) or refusing to participate further (n=10). 36 participants were recruited with one loss to follow up in the placebo group, respectively, by three weeks. Therefore, a total of 35 participants completed the study (omega-3 group n=18; placebo group n=17).
No adverse effects were reported by any of the participants, retained or lost, at any stage of the trial.  Also, the physical activity level of the participants who completed the trial (n=35) remained unchanged.

Lipid Profile
The two groups had similar lipid profiles at baseline (Table 3). At the three-week follow-up, there were no significant changes, within or between groups, for TG, TC, LDL-C, and LDL-C/HDL-C. After intervention HDL-C was significantly increased in both groups (omega-3: p=0.001; placebo: p=0.013), although, after adjustment for the baseline values, Lipid Profile showed no statistically significant intergroup difference.

Anthropometric Measures
As presented in Table3

Discussion
This study investigated the effects of omega-3 on healthy athletes. More specifically, the present study studies showed 700 mg omega-3 caused weight gain [43,44]. The range of the weight reduction due to omega-3 supplement was 100 g in Krzymińska- Siemaszko study to 7000 g in the study of Munro et al [45,46]. As presented in this study, weight increased by 467g after supplementation in the intervention group, but after consideration of baseline values, the effect of supplementation was not significant.  The expression of genes such as peroxisome proliferator-activated receptor (PPAR) gamma alters the regulation of fat metabolism [48]. There is also a study that suggests omega-3 could improve body fat reduction through change the activity of anabolic and anti-catabolic pathways, which promotes the Volume 1(1): 2020 maintenance of muscles and increased metabolic rate, specifically the mammalian target of rapamycin (mTOR) [49,50].
In our study, in blood lipid profile just significant improvements were observed in the HDL-C after inter-group analysis, although considering betweengroup analyses showed no statistical significance between omega-3 and the placebo group. In agreement with our study, one study showed HDL-C increased after 6-weeks supplementation with 5. Animal studies showed omega-3 consumption can reduce food intake in rodents [58,59]. Human studies in this regard are limited and inconclusive. Safaeiyan increasing dietary omega-3 by increased 3.6% of total energy intake did not have any effect on food intake [61]. Our study showed omega-3 after 3-weeks increased energy and protein intake, but after adjustments, the results were not significant. In agreement with our findings. Elevated appetite could increase food intake. There is evidence suggesting that omega 3 may decrease appetite and increased thermogenesis; the reason would be increased plasma concentrations of adiponectin and leptin [62 -66].
One of the limitations to this study was the low dose

Conclusion
Based on our findings, supplementation with omega-3 in healthy adult men resulted in improving body composition status, including decrease FM, FFM, the body fat percent, and energy and protein intakes.
After baseline adjustments, omega-3 supplementation seems to be not effective in decreased FM, and increased HDL-C, and energy and protein intake in elite athletes. Omega-3 fatty acids supplementation may increase HDL-C that helps to prevent obesity, metabolic syndrome, and hypertriglyceridemia.
Further studies are recommended to determine the effect of different doses of omega-3 on adipose tissue and blood lipids in athletes with low fat mass.  1003170207-1003170207.