Effect of Docosahexaenoic Acid on a Biomarker of Head Trauma in American Football.
Level 2 - randomized trial
Individual randomized double-blind placebo-controlled trial
PubMed 26765633 · doi:10.1249/MSS.0000000000000875
What was done
In a randomized, double-blind, placebo-controlled parallel design, 81 NCAA Division I American football athletes were assigned to receive 2, 4, or 6 g/day of DHA or a placebo for 189 days. Blood was sampled across the season during varying contact intensities to measure plasma DHA and serum neurofilament light (NFL), a biomarker of axonal injury. Standardized magnitude-based inference was used to analyze outcomes.
What was found
DHA supplementation increased plasma DHA dose-dependently (mean difference from baseline ± 90% CL: 2 g/d = 1.3 ± 0.6%; 4 g/d = 1.6 ± 0.7%; 6 g/d = 2.8 ± 1.2%). Starters had higher serum NFL area under the curve than nonstarters (1995 ± 1383 pg·mL vs 1398 ± 581 pg·mL; P = 0.024). Irrespective of dose, DHA supplementation attenuated serum NFL increases with small to moderate magnitude (effect size = 0.4 to 0.7).
Why it matters
This study provides randomized controlled trial evidence that prophylactic DHA supplementation can reduce a blood biomarker of axonal trauma from subconcussive impacts in contact sports.
Limits
The study measured only a surrogate serum biomarker (NFL) without clinical, neurological, or cognitive functional outcomes. The population was limited to male NCAA Division I football athletes, head impact kinematics were not individually quantified in the abstract, and magnitude-based inference was used rather than standard frequentist hypothesis testing for the primary DHA effect.