Omega-3 capsules are usually fish oil, krill oil or algal oil for vegetarians. The NIH fact sheet says higher intakes of EPA and DHA lower triglycerides, and eating fatty fish as part of a healthy diet is linked to better heart health. Check EPA plus DHA per capsule rather than just 1000 mg fish oil. Common side effects include fishy burps and stomach upset. If you take blood thinners such as warfarin, ask a doctor before using high doses. Eating oily fish twice a week is still the simplest way to get omega-3.