If you take fish oil supplements for the health benefits of omega-3 fatty acids, you better make sure they're fresh or you may be doing your body more harm than good. Fish oil can quickly go rancid, which can cause free radicals in your body.
To avoid taking oxidized fish oil, buy a high-quality oil and check the expiration date on the bottle. Even if the oil has not expired, try tasting the encapsulated oil either by chewing it or simply stick a needle into the gel cap to take a small taste. If it's rancid, you'll know it.
If the oil tastes fresh, then store it in a refrigerator. You should repeat the taste test almost weekly until the bottle is empty to ensure freshness.
Research has found that the essential polyunsaturated fatty acids in fish oil promote cardiovascular health, protect against stoke and heart attack, improve brain function, and help fight certain cancers, inflammation and depression.