I disagree... Essential fatty acids are only needed in small quantities. When we start consuming them in massive amounts...
PUFAs and HUFAs, when consumed in large quantities are associated with some fairly ugly epidemiology.
Everything is associated with some fairly ugly outcomes when consumed in excessive amounts. Drink 10 liters of water a day and you will wreck your kidneys. Yet no sane person would ever drink such a toxic amount of water. It may be a bit easier to overdose on fish oil, but to achieve the average Japanese tissue levels of omega 3 HUFAs an estimated ~1.7% of total daily calories or 3.7gr of EPA and DHA would be required for the avarage American with a caloric intake of 2000 kcal.[1]
This is, of course, because the avarage American consumes
way too much linoleic acid from refined vegetable oils. The avarage Japanese attains this tissue levels (~60% of HUFAs) with "only" about 0.38% of calories as EPA and DHA, which translates to 830mg, because less dietary omega 6 fatty acids compete with the omega 3s.
Once again, we have to look at the dose-response curve for every fatty acid (or at least for every group of resonably closely related fatty acids) seperately in order to determine their optimum intake levels and carefully consider epidemiological evidence from differing dietary patters around the world.
The dietary patterns associated with the highest rates of cenetarians and the lowest rates of cancer, cardiovascular disease and other age related and chronic diseases are those of the Japanese and certain Mediterranean regions. Both have in common a relatively high intake of omega 3s, with a significant amount of long-chain EPA and DHA, and a relatively low intake of omega 6s (a ratio of >= 1:4 compared to the American ratio of << 1:10). The traditional crete diet is about 10% higher in fat than the avarage Japanese diet (26%) but remarkably most of that difference is made up by monounsaturated fatty acids.[2][3]
I certainly don't recommend mega dosing of fish oil (except for those having hypertriglyceridaemia) but I think almost every westerner could benefit from 0.5 to 1gr of supplemental EPA and DHA in addition to regular fish consumption, especially given the difficulty of avoiding omega 6s in our contemporary food environment.
Still, decreasing our intake of the latter to less than 10% of total calories should be at least as much of a priority as increasing omega 3s, An ideal distribution might be something like 5% SFAs, 10-20% MUFAs, 5% omega 3s and 5% omega 6s, with ~10% of the omega 3s as EPA and DHA.
[1] J. R. Hibbeln et al.
Healthy intakes of n−3 and n−6 fatty acids: estimations considering worldwide diversity.
Am J Clin Nutr June 2006 vol. 83 no. 6 1483S-1493S.
[2] M. Sugano, F. Hirata.
Polyunsaturated fatty acids in the food chain in Japan.
Am J Clin Nutr January 2000 vol. 71 no. 1 189S-196S
[3] A. P. Simopoulos.
The Mediterranean Diets: What Is So Special about the Diet of Greece? The Scientific Evidence.
J. Nutr. November 1, 2001 vol. 131 no. 11 3065S-3073S
Edited by timar, 30 November 2013 - 01:49 AM.