Omega-3s: EPA, DHA, and What Human Trials Actually Show

Written by the MetricFit Research Team | October 11, 2026

Fish oil is the second most popular supplement after multivitamins. Here is what controlled human research supports.

Established physiology

EPA and DHA contribute to normal heart function (EFSA-authorized, 250 mg/day threshold) and DHA contributes to maintenance of normal brain function and vision. These are nutrient-function claims, not treatment claims.

The trial record

Results differ by population and formulation. REDUCE-IT (2019) showed icosapent ethyl (a purified high-dose EPA drug) reduced cardiovascular events in high-risk patients on statins. In contrast, STRENGTH (2020) with a mixed EPA/DHA product was neutral. The lesson: formulation, dose, and baseline risk all matter.

Practical guidance

• Food first: 1–2 servings of oily fish per week aligns with most dietary guidelines.
• If supplementing, check the EPA+DHA content per serving (not “fish oil” grams) and choose products with third-party oxidation testing.
• People on anticoagulants should discuss fish oil with a physician — bleeding risk at high doses is debated but not zero.