Medoro, A., Buonsenso, A., Centorbi, M., Calcagno, G., Scapagnini, G., Fiorilli, G., & Davinelli, S. (2024). Omega-3 Index as a Sport Biomarker: Implications for Cardiovascular Health, Injury Prevention, and Athletic Performance. Journal of functional morphology and kinesiology, 9(2), 91. https://doi.org/10.3390/jfmk9020091
This article takes a deep dive into omega-3 fatty acids—EPA and DHA—and explains why they matter so much for athletes. The main focus of this review is on the omega-3 index (O3I), a blood-based marker that shows how much EPA and DHA are built into red blood cell membranes. The authors argue that O3I is a practical and promising tool for understanding cardiovascular health, injury risk, recovery, and performance in both elite and recreational athletes.
Why do omega-3s matter in the body?
Omega-3 and omega-6 fatty acids are essential building blocks of cell membranes. They help control how flexible membranes are, how cells communicate, and how inflammation is regulated. Because humans can’t make the starting materials for these fats on their own, diet plays a huge role in determining how much ends up in tissues.
Omega-6 fats (like arachidonic acid) tend to produce compounds that promote inflammation, blood clotting, and vasoconstriction—important in small amounts, but problematic when they dominate. Omega-3 fats (EPA and DHA), on the other hand, produce molecules that reduce inflammation and actively help the body resolve it. Since both omega-3s and omega-6s use the same enzymes, having enough omega-3s in the diet helps keep this system balanced.
Training—especially intense or high-volume training—changes how fats are used for energy and how they’re incorporated into cell membranes. Over time, this can lower EPA and DHA levels, potentially shifting athletes toward a more inflammatory state if intake isn’t adequate.
What does the omega-3 index actually measure?
The omega-3 index reflects the percentage of EPA and DHA in red blood cell membranes. Red blood cells are used because they’re stable and represent long-term intake rather than short-term diet changes. That makes O3I a reliable, “low-noise” marker.
In general:
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Below 4% → higher cardiovascular risk
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Around 8% or higher → protective
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Athletes are often encouraged to aim for 8–11%
So what’s the problem? Many athletes—across endurance, team, and strength/power sports—fall well below this range, even when they’re otherwise very fit.
Cardiovascular health
Even though athletes are active, cardiovascular risk doesn’t simply disappear—especially in sports with larger body mass, intense workloads, or long careers. The article reviews evidence showing that higher O3I levels are linked to better heart health, including improved heart rate control, better blood flow, reduced inflammation, and lower risk of arrhythmias.
Supplementation studies consistently show that omega-3 intake raises O3I in a dose-dependent way. Athletes who start with low omega-3 levels tend to improve the most. Some evidence suggests that recreational or non-elite athletes may respond faster than elite athletes, possibly because elite athletes already operate near physiological limits.
Injury prevention and brain health
Omega-3s also play a big role in managing inflammation after training and injury. Higher EPA and DHA levels are associated with lower levels of inflammatory markers, less muscle damage, and better recovery. By influencing key pathways like NF-κB, omega-3s help prevent inflammation from becoming excessive or chronic.
One especially interesting area is brain protection in contact sports. DHA is a major structural fat in the brain, and head impacts can reduce DHA levels. Studies in American football players show that omega-3 supplementation increases O3I and blunts rises in neurofilament light—a marker of repetitive head trauma. This suggests omega-3s may help protect the brain over a long season.
Lower O3I has also been linked to higher rates of tendon problems and running-related injuries, making it a potential marker for identifying athletes who may be more injury-prone.
Performance and recovery
Omega-3s may support performance by improving how efficiently muscles and the cardiovascular system work. The strongest evidence is in endurance sports, where higher O3I is linked to lower oxygen cost during exercise, reduced submaximal heart rate, better running economy, and, in some cases, higher VO₂max.
Effects on strength and power are less clear. Omega-3s may enhance muscle protein synthesis and anabolic signaling, but this benefit seems limited when athletes already consume enough protein or are highly trained.
When it comes to muscle soreness and fatigue, results are mixed. Some studies show less delayed-onset muscle soreness and faster recovery—especially in people with higher O3I—while others find no meaningful effect. Differences in dosage, study length, training status, and timing likely explain these inconsistencies.
Practical Implications of Omega-3s for Athletes
1. Most athletes likely need more omega-3s than the general population
Training increases fatty acid turnover and can lower EPA and DHA levels over time. Many studies show athletes commonly sit below the protective O3I threshold (~8%), even when otherwise healthy. Although exact cut-offs for athletes aren’t fully established, evidence consistently points to ≥8% O3I as a meaningful target for cardiovascular protection and recovery support. Dietary intake alone often isn’t sufficient, especially during heavy training or competition periods.
2. Omega-3 supplementation can support heart health—even in “fit” athletes
High fitness does not eliminate cardiovascular risk. Omega-3s improve heart rate control, blood flow, and markers linked to arrhythmias and sudden cardiac events. Particularly relevant for football players, endurance athletes, and athletes with high training loads or large body mass. Omega-3s should be viewed as cardiovascular insurance, not just a recovery aid.
3. Contact-sport athletes may benefit from DHA for brain protection
DHA is highly concentrated in the brain and is depleted following repetitive head impacts. Supplementation has been shown to blunt increases in markers of brain injury. Athletes in contact and collision sports such as football, rugby, and hockey, should prioritize DHA-rich supplementation, especially during their competitive season. Omega-3s should be considered as part of a long-term brain health strategy, not just post-TBI care.
4. Higher O3I may reduce injury risk and support recovery
Higher omega-3 status is linked to lower inflammation, reduced muscle damage, and fewer tendon-related injuries. It may also help control excessive inflammation without blocking normal adaptation. Omega-3s can support training consistency by reducing injury risk rather than directly “boosting performance.” Again, it can be particularly useful during high-volume or high-intensity training blocks.
5. Endurance athletes may see the most performance benefit
Evidence is strongest for endurance-related outcomes: lower oxygen cost, lower submaximal heart rate, improved running economy, and sometimes improved VO₂max. Omega-3 supplementation is more likely to improve efficiency rather than peak power or maximal strength. Small physiological gains can matter a lot over endurance races.
6. Strength and power athletes: benefits are less clear
Omega-3s may enhance muscle protein synthesis signaling, but benefits seem limited when protein intake is already optimal or in highly trained athletes. Omega-3s shouldn’t replace adequate protein and calories. Use them primarily for health, recovery, and inflammation management, not as a guaranteed strength booster.
7. Supplementation takes time
Omega-3s need time to incorporate into cell membranes. Acute dosing won’t deliver immediate benefits. Expect 2–4 weeks for measurable changes in O3I. Start supplementation before intense training blocks or competition seasons. One-size-fits-all dosing is less effective than O3I-guided strategies.
Omega-3s aren’t just “recovery supplements.” For athletes, they’re a health, durability, and efficiency tool. Using the omega-3 index to guide intake can help reduce cardiovascular risk, protect the brain, lower injury rates, and support endurance performance—especially when training demands are high.
