It’s often promoted to protect the heart, boost mood, reduce inflammation and support overall health. But how much of this is backed by science, and when might fish oil supplements actually be worth ...

Fish oil has mild anti-inflammatory effects. In people with inflammatory arthritis (such as rheumatoid arthritis), omega-3s can reduce joint tenderness and morning stiffness.

Healthy fats are essential—but doctors flag potential side effects to keep in mind if you're taking them in supplement form.