Is Omega-3 Index useful for fatigue?

The Omega-3 Index measures the percentage of EPA and DHA in red blood cell membranes and reflects long-term omega-3 status. Low levels are linked to higher inflammation (e.g., CRP), which could theoretically contribute to fatigue. However, direct evidence for a causal role of the Omega-3 Index in fatigue is limited. Most data come from observational studies or small intervention trials with mixed results. Some RCTs show modest fatigue reduction in individuals with low baseline omega-3 status, especially in chronic inflammatory conditions. For healthy individuals without deficiency, the benefit is unclear. The Omega-3 Index is a blood biomarker, not a genetic test. Its utility for fatigue is constrained by the multifactorial nature of fatigue (sleep, stress, iron, thyroid, etc.). Optimizing the index to 8–12% may be reasonable but should not be seen as a standalone solution. Evidence: human-moderate (observational, small RCTs). Caveat: no meta-analysis specifically on Omega-3 Index and fatigue.