Quote:The importance of a diet rich in fish oils - now a billion dollar food-supplement industry -- has been debated for over half a century
And the medical / nutritional debates will continue to flip-flop about it for another half-century because studies in this [broader] area of scientific investigation have become infamous for their unreliablity both pro and con regarding their examined targets.
Ourselves as "this particular person" is not the generalized human being having a generalized effect or non-effect or bad / beneficial reaction which abstract data outputs conclusions about. We are instead discrete bodies experiencing our own actual specific circumstances and empirical consequences in response to something. Joe Schmo claims that _X_ does nothing to thin his blood, while I bleed like a hemophiliac from the most minor cut if I take an excessive number of softgels / capsules a day.
There is definitely some bad fish oil out there that is contaminated with heavy metals and toxic chemicals, poorly effective due to destructive processing methods, etc. Some of it isn't even really marine-source oil at all, doesn't even contain EPA and DHA.
Sometimes the pharmaceutical industry is indirectly funding and ghost-writing research to bump off an over-the-counter rival. Sometimes it's the supplement industry employing lab workers or financially tweaking lab work to yield exaggerated claims.
Simply failing to advise test-subjects to take a supplement with food can skewer the results due to either decreased absorption and/or beneficial association with those other nutrients. Prescribing a low, ineffective dosage can help achieve negative results, too (CoEnzyme Q-10 never did anything for my mother's endurance of a heart problem till she obstinately got up to 400 milligrams a day [plus] amount after over a month's time). On the opposite side, some supplements in tests are intentionally corrupted with cheap amounts of actual medicinal agents to spike the results favorably.