If you have a certain version of a gene called FADS1 (like the T version of rs174537), you might naturally have lower levels of healthy omega-3 fats like EPA and DHA in your blood — and this has been seen in many different groups of people.

What we've found so far is that having the T allele in the FADS1 gene at the rs174537 variant may be linked to lower levels of EPA and DHA in the blood. Our analysis of the available research shows this pattern has been observed across multiple groups of people [1]. We looked at 20 studies or data points that examine how this specific gene variant affects omega-3 fatty acid levels. All 20 support the idea that people with the T allele tend to have lower baseline levels of EPA and DHA—two important omega-3 fats found in fish oils that support heart and brain health [1]. We did not find any studies that contradict this. The FADS1 gene plays a role in how the body processes fats, including converting shorter-chain fats into longer-chain ones like EPA and DHA. The T allele at rs174537 appears to reduce the activity of this gene, which may explain why those who carry it show lower levels of these fats in their blood [1]. Our current analysis suggests the evidence leans toward a consistent link between this genetic variant and reduced EPA and DHA levels. However, we don’t yet know how much this affects long-term health, or whether increasing dietary intake of omega-3s (like from fish or supplements) can fully offset this genetic difference. What this means for you: If you have the T allele, you might naturally have lower EPA and DHA levels. Eating more fatty fish or using omega-3 supplements could be worth considering, but we’re still learning how much that helps for people with this gene variant. This is what we’ve found so far—our understanding may grow as more evidence becomes available.