Written by Joyce Smith, BS. DHA supplementation during football season significantly decreased the serum level of neurofilament (NFL), a sensitive biomarker of brain cell injury due to head impacts occurring in football players over the course of a football season.
Neurofilament light chain protein (NFL) is a sensitive marker of brain cell (neuron) injury in patients suffering from traumatic brain injury. Repetitive head injuries damage the neurofilaments of brain cells which are released into the blood stream and can be used as a biomarker to assess the extent of brain injury.1 American football is associated with the highest incidence of concussion 2 or mild traumatic brain injury (mTBI), the term commonly used when referring to team sports. 3
Studies have shown that supplementing with docosahexaenoic acid (DHA) reduced the brain cell damage in rats when given to them before subjecting them to head injuries.4 Researchers hypothesized that American football players would need higher doses of supplemental DHA because of their larger size and physical activity; therefore, would supplementing with DHA decrease serum NFL in players over the football playing season. To test their theory, they conducted the following study 5 to investigate the effects of supplementing with varying doses of DHA (2, 4, and 6 gram doses) on plasma fatty acids and serum NFL, in 130 American football athletes over the course of a football season. Football season consisted of 189 days: 57 days of off-season conditioning, 23 days of preseason camp, and 109 days of competitive season. Researchers would observe whether serum NFL, a biomarker of head trauma, would increase with an increase in the number and severity of head impacts.
Football players were selected for this study by position (quarterback, offensive line, etc.) and then further randomized into one of the following four treatment groups: 2 grams DHA daily (n=30), 4 grams daily (n=37), or 6 grams daily (n=36) or a placebo (n= 26). The DHA used in this study was DHA oil derived from Schizochytrium sp containing 35 – 45% DHA by weight. The placebo consisted of Wesson oil and contained less than 0.1% DHA.
Players were also instructed to limit foods high in DHA to two servings per week during the study. Supplements were given to players only on the days when they reported to the training facility which were the 5, 7, and 5- day weeks for summer training, preseason camp, and competitive season respectively. Baseline blood samples were taken at Baseline –after 9 weeks of off season summer conditioning with no contact; Precamp– at the end of summer training before preseason training camp; Postcamp and during Competitive season on the Monday following a Saturday game where head impacts were most common. [Starters were those players who were on the most active and winning teams and who took the majority of head injuries (approximately 20 – 40+ per game)]
How did supplemental DHA affect plasma DHA over the course of the football season?
- Supplementing with DHA significantly increased plasma DHA levels from baseline to end of the season in the 6,4, and 2 gram treatment groups as follows: 99.6% increase at the 6 gram dose and lesser increases at the 4 gram dose (P=0.006) ; and at the 2 gram dose (P=0.001).
- Supplemental DHA also significantly increased plasma EPA in the 6 gram group P<0.001.
How did serum NFL change over the course of the season?
Serum NFL increased substantially over the course of the season in participants categorized as starters compared to with non-starters. In fact, serum NFL increased with the number and severity of head impacts as well as the hours of contact.
- During Postcamp the increase in serum NFL was small in starters (P=0.001) compared to baseline ; however, when the competitive season began there was an almost 100% increase in serum NFL (P<0.001) which coincided with conference play. An additional increase in serum NFL occurred as the competitive season progressed and remained elevated at the end of the competitive season (P<0.001).
- Nonstarters had most contact during time from Precamp to Postcamp (P=0.043) and when comparing starters to nonstarters; the increase in serum NFL was substantial (P=0.024).
How did DHA supplementation affect serum NFL?
Non-starters had no change in serum NFL and were excluded from further analysis. Compared to baseline, supplemental DHA likely (92.3%) attenuated serum NFL during Postcamp (P=0.070) at which time a substantial increase in serum NFL was observed in starters.
A second substantial increase in serum NFL was observed in starters during conference play. During this time, DHA supplementation resulted in a likely (87.1%) lowering effect compared to placebo (P=0.144).
This effect continued through to the end of the football season when a likely 98.9% reduction in serum NFL was observed in starters (who supplemented with DHA) compared to placebo (P=0.012)
Interestingly, the 2-gram dose of DHA appeared to produce the most decrease in NFL compared to placebo. It was only at the end of the study time that a likely (91.0%) substantial decrease in NFL was observed in those taking 4 grams of DHA. Because the number of starters in each treatment group varied, comparing the groups for “most effective” DHA dose was impossible.
This is the first study to show that DHA supplementation may potentially lower the increase in serum NFL players; therefore suggesting a neuroprotective effect of DHA. However, future studies are needed to determine its use as a potential prophylactic agent.
Source: Oliver, Jonathan M., Margaret T. Jones, K. Michele Kirk, David A. Gable, Justin T. Repshas, Torie A. Johnson, Ulf Andreasson, Niklas Norgren, Kaj Blennow, and Henrik Zetterberg. “Effect of docosahexaenoic acid on a biomarker of head trauma in American football.” Med Sci Sports Exerc 48, no. 6 (2016): 974-982.
Copyright © 2016 American College of Sports Medicine
Posted September 14, 2017.
Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.
References:
- Siedler DG, Chuah MI, Kirkcaldie MT, Vickers JC, King AE. Diffuse axonal injury in brain trauma: insights from alterations in neurofilaments. Frontiers in cellular neuroscience. 2014;8.
- Daneshvar DH, Nowinski CJ, McKee AC, Cantu RC. The epidemiology of sport-related concussion. Clinics in sports medicine. 2011;30(1):1-17.
- DeKosky ST, Blennow K, Ikonomovic MD, Gandy S. Acute and chronic traumatic encephalopathies: pathogenesis and biomarkers. Nature Reviews Neurology. 2013;9(4):192-200.
- Schober ME, Requena DF, Abdullah OM, et al. Dietary docosahexaenoic acid improves cognitive function, tissue sparing, and magnetic resonance imaging indices of edema and white matter injury in the immature rat after traumatic brain injury. Journal of neurotrauma. 2016;33(4):390-402.
- Oliver JM, Jones MT, Kirk KM, et al. Effect of docosahexaenoic acid on a biomarker of head trauma in American football. Med Sci Sports Exerc. 2016;48(6):974-982.
