Americans spend a lot of money on fish oil purchases -- more than $1 billion per year on over-the-counter fish oil supplements (and that doesn't even count the jar of peanut butter plus omega-3 fatty acids you keep in your pantry) [source: LeWine].
Fish oil will probably not make any discernible impact on your child's intelligence, or protect against Crohn's disease or mental illness including major depression. Many of us take fish oil capsules believing the omega-3 fatty acids will reduce our risk of developing heart disease; while some studies suggest that fish oil supplements may have heart-healthy benefits, conflicting recent research finds its heart benefits may be bunk. Or at the very least, inconclusive or biased. Studies are finding that patients with cardiovascular disease do not have any reduction in their risk of having a(nother) heart attack, nor does fish oil lower their risk of stroke, congestive heart failure or any other cardiovascular condition after taking supplements for a minimum of one year.
While fish oil doesn't live up to the hype that surrounds it, it's also not a snake oil remedy – research shows promise that adding it to your diet helps protect against colorectal cancer. The best way to get your daily intake of fish oil isn't with supplements. Eat fish. (For you non-meat eaters, flax is a good substitute.)