We recently published a systematic review (Lewis et al. 2020  ) entitled, “Are there benefits from the use of fish oil supplements (FS) in athletes?”.
Why? For three primary reasons: 1) Despite 100+ publications investigating fish oil supplements in athletes over the past 25 years, there were no systematic reviews collating the evidence and providing a consensus of opinion, specifically for the evidence in elite athletes; 2) training leads to improvements in omega-3 status, namely increases in the Docosahexaenoic acid (DHA (22:6n–3)) content of cell membranes , which may result in athletes by virtue of years of training, having less or no need for supplementation with FS; 3) Expert groups, such as the International Olympic Committee and the American College of Sports Medicine were either reportedly, “unclear if FS should be pursued by athletes” or offered no guidance.
What did we conclude? We found that FS exert consistent positive effects on cognition and mood, cardiovascular dynamics (in cyclists), and muscle recovery. In addition, that FS attenuate proinflammatory cell responses (i.e., TNF-alpha) and increased lipid peroxidation and post-exercise nitric oxide. No benefits for FS were seen on endurance exercise performance, training adaptations, muscle force, or lung function (other than in cases of exercise induced bronchoconstriction (EIB)). What was important to establish was any evidence for a negative effect of FS on performance. Indeed, any reported side effects were mild, although we did identify one case of a duodenal ulcer associated with high dose FS. It was noteworthy that many of the randomised controlled trials (RCT) that reported positive effects for FS, used doses that were achievable through the consumption of oily fish in the diet; a fact which should not be lost given the concerns expressed over supplemental FS quality in the scientific literature. With regards to dietary sources, the long-chain poly unsaturated omega-3 (n–3) fatty acids present in FS, namely DHA (22:6n–3) and EPA (20:5n–3) are natural constituents of seafood including algae, crustaceans, and to a much a lesser extent dairy and meat (the diet of the animal influencing the n–3 fatty acid content).
We made recommendations for future FS research, including the measurement of biomarkers of n–3 fatty acid status within research studies (this is something we do routinely at Orreco with our athletes), to allow for the proper investigation and understanding of the impact of n–3 fatty acid status and the dose–response on outcomes. In addition, we reported that there is a need to further our understanding of the impact ofFS on neuromuscular performance, bone metabolism, rehabilitation from injury( e.g. surgical compared with nonsurgical outcomes including bone stress), EIB, risk of illness, and risk of sudden cardiac death in athletes.
Prior to commencing the systematic review, we had become increasingly aware of a growing interest in the application of FS as a preventative agent for concussion in athletes, and as a post-injury treatment adjunct to medical management for head injuries resulting from either a military or non-athletic related head trauma ,. Indeed, there has been a strong call recently by ex-professional athletes in Rugby Union and Rugby League for more research into protecting the brains of athletes in contact sports; see BBC sport articles here and here. Our systematic review methodology captured only one RCT in athletes reporting a beneficial effect of DHA specifically, on lowering a biomarker of neuronal injury in American footballers. Although this is indeed a positive outcome from the use of DHA, it is perhaps disappointing that no studies have been completed to date with regards to investigating the effect of DHA on recovery from concussion. The lack of RCT data is not just confined to athlete studies, as the first clinical human trial investigating the effects of DHA as a treatment for paediatric concussion related to sports injury is only now nearing completion (registered at clinicaltrials.gov. as NCT01903525). There are however, documented clinical cases, providing insight into the experience of physicians in using FS as part of the treatment for head trauma cases. For example, Lewis et al, (2016)  describes three severe traumatic brain injury (TBI) cases whereby ~ 20g omega-3 fatty acids (~9g EPA & ~6g DHA) where administered as part of the patient’s medical management to: a sole surviving miner following an explosion; a teenager involved in a motor vehicle accident; and a young girl injured in a near drowning accident. All three patients recovered, and no adverse events were recorded. That said, a fatal coagulopathy was reported following a TBI, whereby the patient was already taking high doses of FS (dose not documented) and the interaction with administered warfarin was fatal . These cases emphasise the importance of seeking clinical trial data and assessing omega-3 status, specifically EHA and DHA, in each patient prior to high dose FS, as high doses maybe lead to an adverse outcome.
Back to the sporting context. What can we do now for the athlete? We should firstly measure omega-3 status in order to capture fatty acid profiles that gives us greater objectivity in answering whether a given athlete would benefit from FS; certainly, avoiding any deficiencies is paramount. Recognising that athletes who follow a vegan diet are at high risk of DHA and EPA deficiencies. In fact we should encourage the consumption of dietary sources where the athlete is open to such advice. Consider monitoring of the athlete’s omega-3 status periodically to allow for adjust to the supplementation regime where necessary and recognise that DHA and EPA can exert significant positive effects on the athlete’s physiology. In conclusion, the last ~25 years of research has uncovered several applications for FS in athletes, that said, we are still only at the infancy of the application of FS in protecting the athlete from the effects of concussion and TBI.
Take home messages:
1. Some clear evidence for beneficial effects of fish oils in athletes
2. More is not always better when it comes to any supplementation. Measurement and monitoring of omega-3 status allows for objectivity around supplementation of fish oils.
3. Despite some promising results to date, more research is needed.
1. Lewis NA, Daniels D, Calder PC, Castell LM, Pedlar CR. AreThere Benefits from the Use of Fish Oil Supplements in Athletes? A SystematicReview. Advances in Nutrition 2020; 11(5): 1300-14.
2. Helge JW, WuBJ, Willer M, Daugaard JR, Storlien LH, Kiens B. Training affects muscle phospholipid fatty acid composition in humans. Journal of Applied Physiology 2001; 90(2): 670-7.
3. Bailes, J. E., &Patel, V. (2014). The potential for DHA to mitigate mild traumatic brain injury. Military medicine, 179 (suppl_11), 112-116.
4. Lewis MD.Concussions, Traumatic Brain Injury, and the Innovative Use of Omega-3s. Journal of the American College of Nutrition2016; 35(5): 469-75.
5. Gross BW, Gillio M, Rinehart CD, Lynch CA, Rogers FB. Omega-3 Fatty Acid Supplementation and Warfarin: A Lethal Combination in Traumatic Brain Injury. Journal of Trauma Nursing | JTN 2017; 24(1): 15-8