I have to say I don't believe any of the supposed benefits of eating Omega-3 or -6 oils over butter, milk, cheese cream and olive oil, etc.
They're all fats: fatty acids with the COOH acid group at one end. The Omegas happen to have the COOH group at the Omega - arse - end.
Course there are probably trace elements like iodine and phosphorus in fish oils that may be beneficial but humans have been eating both saturated and unsaturated fats for millions of years and they're broken down in exactly the same way in the body.
All natural unsaturated and polyunsaturated fatty acids have their hydrogen double bonds on one side - the cis side.
Trans fats - fats made from oils by hydrogenation with a nickel catalyst - have their double hydrogen bonds on two sides, and cannot be broken down completely by the usual enzymes, so leave bits of fatty acid molecules swanning round our alimentary and vascular systems. Not good...
IMO with fats the important aspect is not so much quantity, it's about ratios between specific types of fat. In respect of this, supplementation is only beneficial if used to correct an out of synch ratio - but then getting the same fats from diet would be equally beneficial.
As for the actual health benefits of having a healthy balance of fats, it's a subtle thing with effects being noticed more in the sense of what doesn't tend to happen to you (lower risk of many potential issues) rather than some sudden wonderful feeling of being the healthiest human alive.
The mechanism of effect that lipids have on health is normally not the fat itself or any bound minerals, but effects on transporter molecules and receptor sites. While certain fats are required for certain structures, and very low intake can cause a deficiency, in most cases even a very low fat diet will provide enough provided it contains enough food to avoid overal malnutrition.
Us western worlders, who generally eat a diet high in processed foods and exercise little, often exerpeince a range of non pathogen related diseases, and many of these problems are closely related to and influenced by eating unbalanced levels of all kinds of nutrients.
We then take a supplement and, whoa things get better, and the supplement gets the label of a wonder supp... but in relaity we are looking at it backwards, and just correcting an issue with diet that would not exist if we ate a diet that was closer to how nature intended.
Very complex subject though, and as genetic differences between individuals considerably influence the magnitude of effect of a particular fatty acid on a particular physiological response, there's actually no sepcific one-size-fits-all approach to the balance of fats that each individual should take for optimum health.
As far as I know there have been over thirty genes so far identified that have polymorphims that each will modify the physiological response to intake of a particular fatty acid or group of fatty acids... the often knocked 'lipid hypothesis' of CVD disease makes a helluva lot more sense suddenly when these genetic factors are incorporated into the otherwise inconsistent theoretical model of disease.
The best approach IMO, since none of us can know our genetic variants without very expensive testing, is to minimise excessive reliance or excessive exclusion of any one particular type of fatty acid, to seek to maintain the very obviously beneficial ratios (as between omega 3 and omega 6) and to avoid artificially altered fats.
