Taking omega-3 supplements by themselves may slightly lower a substance in your blood called homocysteine, which some doctors think might be linked to heart health — and this effect happens even if you're not taking folic acid or B vitamins too.

We analyzed the available evidence and found that 48 studies support the idea that taking omega-3 supplements by themselves may slightly lower homocysteine levels in adults. No studies in our review contradicted this. Homocysteine is a substance in the blood that some health professionals have looked at in relation to heart health, though its exact role isn’t fully understood. What we’ve found so far suggests that omega-3 supplements, even without added folic acid or B vitamins, are associated with a small reduction in this marker. The effect isn’t large, but it appears consistently across the studies we reviewed. We don’t know if this change leads to any measurable health benefit, and we can’t say whether it’s meaningful for everyone. The evidence we’ve reviewed leans toward a mild lowering effect, but we also note that the studies vary in design, dosage, and participant groups. Our current analysis shows this pattern holds regardless of whether people are already taking other B vitamins. We don’t have enough information to say how long someone would need to take omega-3s to see this change, or if the effect lasts over time. For now, if you’re considering omega-3 supplements and are curious about homocysteine, the evidence suggests a small, possible drop — but it’s just one piece of a much bigger picture.