Omega-3 fish oil supplements could backfire without this key enzyme

Fish oil’s cancer-fighting reputation may hinge on a little-known gene. Researchers discovered that omega-3s like EPA and DHA help curb colorectal cancer only when the enzyme ALOX15 is present. Without it, fish oil sometimes increased tumor growth in mice—especially DHA. The results suggest that not all supplements work the same way, and genetics could determine who truly benefits.