The Dose-Response Effect of Docosahexaenoic Acid on the Omega-3 Index in American Football Athletes.

PURPOSE: American-style football (ASF) players are at increased risk for head injuries and cardiovascular disease. n-3 polyunsaturated fatty acids are cardioprotective, and emerging evidence suggests benefits for protection against head injuries. However, fundamental knowledge of n-3 polyunsaturated fatty acid dosing in athletes such as ASF players remains poorly understood. Therefore, this study investigated the dose-response effect of docosahexaenoic acid (DHA) supplementation in red blood cells (RBC) and as the Omega-3 Index (O3I), in collegiate ASF players throughout a competitive season. METHODS: Sixty-nine ASF players were randomly assigned placebo (corn oil), or 2, 4, or 6 g·d -1 of DHA supplement. Blood samples were collected at eight time points (T1-T8) over 27 wk. RBC were extracted and analyzed by gas-liquid chromatography. Compliant players who had samples collected at all time points were analyzed. A repeated-measures ANOVA was conducted to assess the dose-response effect of DHA over time, and between-group differences at individual time points were assessed by one-way ANOVA followed by Tukey post hoc test. RESULTS: A significant dose and time interaction was found, and all supplement groups had significantly greater DHA in RBC compared with placebo from T2-T8 ( P < 0.05). Athletes receiving 6 g·d -1 of DHA had the greatest O3I, relative to other groups, and the O3I reached steady state by 15 wk. The 6 g·d -1 group surpassed >8% on the O3I at approximately twice the rate of the 4 g·d -1 group (8 vs 15 wk). CONCLUSIONS: Our findings provide important fundamental knowledge demonstrating a dose-response incorporation of DHA into RBC membranes up to 6 g·d -1 . Furthermore, 6 g·d -1 of DHA can be used to rapidly achieve a desired O3I (>8%) in athletes in only 8 wk.

A Season of American Football Is Not Associated with Changes in Plasma Tau.

American football athletes are routinely exposed to sub-concussive impacts over the course of the season. This study sought to examine the effect of a season of American football on plasma tau, a potential marker of axonal damage. Nineteen National Collegiate Athletic Association (NCAA) football athletes underwent serial blood sampling over the course of the 2014-2015 season at those times in which the number and magnitude of head impacts likely changed. Non-contact sport controls (NCAA men's swim athletes; n = 19) provided a single plasma sample for comparison. No significant differences were observed between control swim athletes and football athletes following a period of non-contact (p = 0.569) or a period of contact (p = 0.076). Football athletes categorized as starters (n = 11) had higher tau concentrations than non-starters (n = 8) following a period of non-contact (p = 0.039) and contact (p = 0.036), but not higher than swimmers (p = 1.000 and p = 1.000, respectively). No difference was noted over the course of the season in football athletes, irrespective of starter status. Despite routine head impacts common to the sport of American football, no changes were observed over the course of the season in football athletes, irrespective of starter status. Further, no difference was observed between football athletes and non-contact control swim athletes following a period of non-contact or contact. These data suggest that plasma tau is not sensitive enough to detect damage associated with repetitive sub-concussive impacts sustained by collegiate-level football athletes.

Effect of Docosahexaenoic Acid on a Biomarker of Head Trauma in American Football.

PURPOSE: American football athletes are exposed to subconcussive impacts over the course of the season resulting in elevations in serum neurofilament light (NFL), a biomarker of axonal injury. Docosahexaenoic acid (DHA) has been reported to reduce axonal trauma associated with traumatic brain injury in rodent models. However, the optimal dose in American football athletes is unknown. This study examined the effect of differing doses of DHA on serum NFL over the course of a season of American football. METHODS: In a randomized, double-blind, placebo-controlled, parallel design, 81 National Collegiate Athletic Association Division I American football athletes were assigned to ingest either 2, 4, 6 g·d of DHA or placebo. Blood was sampled at specific times over the course of 189 d, coincident with changes in intensity, hours of contact, and likely changes in head impacts. Standardized magnitude-based inference was used to define outcomes. RESULTS: DHA supplementation increased plasma DHA in a dose-dependent manner (2 g·d: 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%). Serum NFL increased to a greater extent in starters (area under the curve, 1995 ± 1383 pg·mL) versus nonstarters (1398 ± 581 pg·mL; P = 0.024). Irrespective of dose, supplemental DHA likely attenuated serum NFL coincident with increases in serum NFL by likely small and moderate magnitude (effect size = 0.4-0.7). CONCLUSIONS: Findings from this study, the first large-scale study examining potential prophylactic use of DHA in American football athletes, include identification of optimal dose of DHA, suggesting a neuroprotective effect of DHA supplementation.

Serum Neurofilament Light in American Football Athletes over the Course of a Season.

Despite being underreported, American football boasts the highest incidence of concussion among all team sports, likely due to exposure to head impacts that vary in number and magnitude over the season. This study compared a biological marker of head trauma in American football athletes with non-contact sport athletes and examined changes over the course of a season. Baseline serum neurofilament light polypeptide (NFL) was measured after 9 weeks of no contact and compared with a non-contact sport. Serum NFL was then measured over the course of the entire season at eight time-points coincident with expected changes in likelihood of increased head impacts. Data were compared between starters (n = 11) and non-starters (n = 9). Compared with non-starters (mean ± standard deviation) (7.30 ± 3.57 pg•mL-1) and controls (6.75 ± 1.68 pg•mL-1), serum NFL in starters (8.45 ± 5.90 pg•mL-1) was higher at baseline (mean difference; ±90% confidence interval) (1.69; ± 1.96 pg•mL-1 and 1.15; ± 1.4 pg•mL-1, respectively). Over the course of the season, an increase (effect size [ES] = 1.8; p < 0.001) was observed post-camp relative to baseline (1.52 ± 1.18 pg•mL-1), which remained elevated until conference play, when a second increase was observed (ES = 2.6; p = 0.008) over baseline (4.82 ± 2.64 pg•mL-1). A lack of change in non-starters resulted in substantial differences between starters and non-starters over the course of the season. These data suggest that a season of collegiate American football is associated with elevations in serum NFL, which is indicative of axonal injury, as a result of head impacts.