OMEGA-3 FATTY ACID SUPPLEMENTATION IN PHYSICALLY ACTIVE INDIVIDUALS.

Introduction

The long-chain omega-3 fatty acid (LC n−3 FA) are polyunsaturated fatty acids associated with cognitive, health and performance improvements [1]. The extent to which their parent LC n−3 FA, the “nutritional essential” alpha-linolenic-acid (ALA,18:3n−3) is converted into the “physiologically essential” LC n−3 FA, in particular, eicosapentaenoic acid (EPA, 20:5n−3) and docosahexaenoic acid (DHA,22:6n−3) is very limited (0.2 to 21%) [2] and by no means sufficient to provide the functional benefits associated with EPA and DHA in the human body [3].

EPA and DHA are crucial cell membrane components impacting the lipid content and function of the skeletal, cardiac, or neural tissues [4]. Thus, to assure the necessary incorporation of EPA and DHA into tissue membrane phospholipids along with proper circulating LC n−3 FA status, sufficient diet intake is required. Nonetheless, there is no consensual recommendation for LC n−3 FA intake, except for ALA (e.g., women need 1.1 and men 1.6 g/day) [5]. Current advice from different government bodies and health organizations ranges from 1.4 to 2.5 g/d of LC n−3 FA, with EPA+DHA representing between 140 to 650 mg/d [2] being the recommended average total LC n-3 FA daily intake of ~500 mg for the adult population.

The adequate dietary intake of LC n-3 FA has been associated with functional improvement, impacting mainly on (i) the central nervous system, (ii) the cardiovascular system, (iii) systemic inflammation and (iv) skeletal muscle efficiency [6].

Particularly EPA has been associated with attenuated systemic inflammation and more efficient post-exercise recovery by promoting muscle blood flow. DHA is abundant in the retina, testis, spermatozoids, and brain, being one of the primary structural components of the neuronal cell membrane [1]. Additionally, regular physical activity may induce changes in the muscle phospholipids by increasing the proportion of DHA content and consequently providing trained athletes with a “superior” LC n−3 FA status compared with the sedentary population [6].

ALA is abundant in several vegetable oils, such as chia, perilla and linseed oil and in smaller amounts in walnut oil. EPA and DHA are natural constituents of seafood including, algae, crustaceans, and fish, and to a much lesser extent in dairy and meat (the diet of the animals influences the LC n–3 FA content). Both dietary intake (e.g., eating fish or supplements) and exercise training may change LC n−3 FA status [1]. Nonetheless, it is worth mentioning that the habitual manufacturing food process and environmental issues may significantly reduce the natural concentration of LC n−3 FA in some commercially available products (e.g., fish or eggs) [7].

Effects of LC n−3 FA supplementation to support health and adaptation to exercises in physically active individuals.

LC n−3 FA supplementation, particularly the physiologically essential EPA and DHA has been studied for their effects on the brain, cardiovascular health, muscular performance, and recovery from injury [4].

Due to the anti-inflammatory effects, LC n-3 FA could play a role in recovery from vigorous training sessions, exercise-induced muscle damage or attenuate the severity of post-exercise delayed onset of muscle soreness status [6].

EPA and DHA supplementation has been associated with anabolic effects by promoting muscle protein synthesis and anti-inflammatory actions in young and older individuals [8]. Recent investigations advocate for the LC n-3 FA supplementation, particularly DHA, to reduce the severity of head trauma in athletes subject to repetitive head impacts (e.g., American Football players) and to favour mood, sleep quality, episodic memory, cognition, and reaction time efficiency in physically active individuals [1].

In summary, the available evidence seems to support the increase of dietary LC n-3 FA intake via food (e.g., fatty fish) or supplements, as a pragmatic strategy to enhance cognition protection and physical performance, attenuate the exercise-induced inflammation as well as to speed up post-exercise recovery [1]. Nonetheless, it is worth highlighting that the reported positive effects of fish oil supplementation could be achievable only by ingesting dietary sources such as salmon, sardines or linseed oil.

 Supplementation protocols and quality of the commercialised products

A minimum period of two weeks of regular supplementation with 3 to 5 g/day of fish oil (providing more than 60%, ideally 85-90% of EPA+DHA) is necessary to permit detectable increases in muscle LC n-3 FA lipid composition and promote health [9]. Nonetheless, longer supplementation periods involving four to twelve months would be necessary to increase EPA and DHA content in the red blood cell membrane [10]. The sum of EPA and DHA expressed as a percentage of total fatty acids in erythrocytes represents the Omega 3 index, a recogniser marker of L C n-3 FA status associated with many health indicators and outcomes in the general population [10].

To promote muscle accretion and functional capacity the ingestion of 4 g/day of fish oil supplements containing 1.86 g of EPA and 1.50 g of DHA (EPA-to-DHA ratio ~1.25) has been recommended [8]. This intake is approximately equivalent to the L C n-3 FA content of 200–400 g of freshwater fatty fish (e.g., salmon, herring, and sardines).

To improve cognition and attenuate head trauma, depression, and anxiety, a higher proportion of DHA with an EPA-to-DHA ratio ranging from 1 (equals amounts) up to 0.12 (8 times more DHA) has been suggested [3].

High-quality fish oil supplements should include more than 60% to 85-90%, of total fatty acid from the LC n-3 FA with a relationship between the content of arachidonic acid to EPA lower than 0.04. Furthermore, the inclusion of vitamin E (-tocopherol) to reduce oxidation of the LC n-3 FA, ensuring product stability and prolonging its shelf life is highly recommended [6].

To improve LC n-3 FA bioavailability fish oil supplements in the form of capsule coatings are advised due to their resistance to gastric acid [3].

In summary, LC n-3 FA supplementation should last at least two weeks, ideally 4 to 12 weeks. The ingestion protocol could consist of a daily intake of 3 to 5 g of a high EPA and DHA concentration divided into two daily doses of 1.5 to 2.5 g each (e.g., the first intake before breakfast and the second in the evening, before dinner).

 Adverse effects

Fish oil supplementation appears to be safe in physically active individuals being the most stated concern related to the purity of the commercialised products. There have been reports of fish oils supplement containing heavy metal contaminants and higher concentrations of saturated fats to the detriment of the expected amount of EPA and DHA [11].

The European Food Safety Authority’s scientific opinion states, “Long-term supplemental intakes of EPA + DHA up to about 5 g/day do not appear to increase the risk of spontaneous bleeding episodes or bleeding complications, or affect glucose homeostasis, immune function or lipid peroxidation, provided the oxidative stability of the LC n–3 FA is guaranteed.” Nonetheless, a higher than recommended daily intake of fish oil (>5 g/d) would not be recommendable in healthy physically active individuals without appropriate professional supervision [6,12].

 Practical advice.

Before suggesting fish oil supplements, a thorough diet analysis and the fatty acid blood profile revealing the omega-3 status is highly advisable. Those following a vegan diet could be at high risk of DHA and EPA insufficient intake. In cases where food choice modifications are not possible, the integration of high-quality fish oil supplements should be considered. Periodical controls of the fatty acid profile are necessary to thereafter adjust diet composition and supplementation protocols.

Author

Dr. Fernando Naclerio
Professor in Strength Training and Sports Nutrition
Centre Lead: Centre for Exercise Activity and Rehabilitation
Institute for Lifecourse Development
School of Human Sciences
University of Greenwich, United Kingdom.
Contact email: f.j.naclerio@gre.ac.uk

References

1       Gonzalez DE, McAllister MJ, Waldman HS, et al. International society of sports nutrition position stand: tactical athlete nutrition. J Int Soc Sports Nutr 2022;19:267–315. doi:10.1080/15502783.2022.2086017
2       Leclercq IA, Molendi-Coste O, Legry V. Why and how meet n-3 PUFA dietary recommendations? Gastroenterol Res Pract 2011;2011. doi:10.1155/2011/364040
3       Schuchardt JP, Hahn A. Bioavailability of long-chain omega-3 fatty acids. Prostaglandins Leukot Essent Fatty Acids 2013;89:1–8. doi:10.1016/j.plefa.2013.03.010
4       Rawson ES, Miles MP, Larson-Meyer DE. Dietary supplements for health, adaptation, and recovery in athletes. Int J Sport Nutr Exerc Metab 2018;28:188–99. doi:10.1123/ijsnem.2017-0340
5       National institute of Health (BIH) Omega-3 Fatty Acids Fact Sheet for Consumers https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/.
6       Lewis NA, Daniels D, Calder PC, et al. Are There Benefits from the Use of Fish Oil Supplements in Athletes? A Systematic Review. Advances in Nutrition 2020;11:1300–14. doi:10.1093/advances/nmaa050
7       Nichols PD, Petrie J, Singh S. Long-Chain Omega-3 Oils–An Update on Sustainable Sources. 2010;:572–85. doi:10.3390/nu2060572
8       Valenzuela PL, Morales JS, Emanuele E, et al. Supplements with purported effects on muscle mass and strength. Eur J Nutr 2019;0:0. doi:10.1007/s00394-018-1882-z
9       Owens DJ, Twist C, Cobley JN, et al. Exercise-induced muscle damage: What is it, what causes it and what are the nutritional solutions? Eur J Sport Sci 2018;15:1–15. doi:10.1080/17461391.2018.1505957
10     Tomczyk M, Jost Z, Chroboczek M, et al.  Effects of 12 Wk of Omega-3 Fatty Acid Supplementation in Long-Distance Runners. Med Sci Sports Exerc 2023;55:216–24. doi:10.1249/MSS.0000000000003038
11     Mason RP, Sherratt SCR. Omega-3 fatty acid fish oil dietary supplements contain saturated fats and oxidized lipids that may interfere with their intended biological benefits. Biochem Biophys Res Commun 2017;483:425–9. doi:10.1016/j.bbrc.2016.12.127
12     Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr 2018;15:38. doi:10.1186/s12970-018-0242-y