Omega-3s are essential fatty acids—EPA, DHA, and ALA—with key roles in heart, brain, and eye health. EPA and DHA come mainly from fatty fish like salmon and sardines, while ALA is plant-based and converts poorly in the body. For supplements, choose sustainably sourced fish oil with at least 500 mg of EPA and DHA and minimal additives.

When it comes to supplements, many people take labels at face value—but there’s often more to the story. A little digging is sometimes...