Research

Hormonal

High DHA fish oil supplementation (DHA > EPA) improves cardiovascular efficiency during submaximal exercise by lowering heart rate and improving heart rate variability, without negatively affecting endurance performance.

If you are looking to improve cardiovascular efficiency during moderate exercise, high DHA fish oil (where DHA exceeds EPA) may help lower your heart rate for a given workload. This does not necessarily make you faster (endurance performance was unaffected in some studies), but it may make exercise feel easier by reducing cardiac strain. Look for supplements with a DHA:EPA ratio greater than 1:1, dosed between 1-6g daily.

GoodSupportsHIGH confidence
Buckley et al. (2009) showed that... serum TAG and HR reduced during submaximal exercise... high DHA fish oil improved CV efficiency during submaximal exercise. In this study, high DHA fish oil did not affect endurance exercise performance or recovery. Ninio et al. (2008) reported that high DHA fish oil supplementation improved HRV in volunteers by increasing high-frequency power, and it reduced HR at rest and during submaximal exercise.
Samaneh Ghasemi Fard et al. · Critical Reviews in Food Science and Nutrition · 2018

Why this rating

Based on a systematic review of 113 studies, including multiple randomized controlled trials showing consistent improvements in HR and HRV.

Source

How does high DHA fish oil affect health? A systematic review of evidence

Samaneh Ghasemi Fard et al. · Critical Reviews in Food Science and Nutrition · 2018

DOI 10.1080/10408398.2018.1425978

systematic_reviewCited 242×
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DOI resolved against Crossref · corpus check 2026-06-10

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