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.