“Need” is a funny concept. You don’t need to eat seafood. You don’t need an appendix or legs, either.
An article about the Omega-3 Index was published in Whole Foods Magazine. Scanning through the figures, I noticed a few interesting studies.
For example, Association of marine omega-3 fatty acid levels with telomeric aging in patients with coronary heart disease (Farzaneh-Far et al., 2010)
Telomere length is believed to be a biomarker of aging: the shorter your telomeres, the faster you’re aging. In the study, they measured telomere length in white blood cells and EPA+DHA in whole blood at baseline and again 5 years later.
Quartile 1: EPA+DHA = 2.3% of the fatty acids in whole blood.
Quartile 2: 3.3%
Quartile 3: 4.3%
Quartile 4: 7.3%
Potential confounders: quartile 4 was comprised of educated rich white old non-smokers with low levels of inflammation, but the statisticians assure us those variables were controlled for… so there’s that.
They are conditionally essential at best, only if docosahexaenoic acid (DHA) is lacking. We can’t synthesize omega 3 fatty acids, and indeed they do prevent/cure certain manifestations of “essential fatty acid (EFA) deficiency” (Weise et al., 1958), but DHA can do all that and more. Not that I recommend this, but a diet completely devoid of 18-carbon vege oil fatty acids will not produce EFA deficiency in the presence of DHA. (“vege,” rhymes with “wedge”)
The “parent essential oils” are linoleic acid (LA) and alpha-linolenic acid (ALA). The others, which I think are more important and the truly “essential” ones are eicosapentaenoic acid (EPA), arachidonic acid (AA), but mostly just DHA.
The first manifestation of EFA deficiency is dermatitis (Prottey et al., 1975). Some people say LA is necessary to prevent this, but it would be better phrased as “LA prevents dermatitis;” not “LA is necessary to prevent dermatitis.” All of the evidence suggesting LA is essential is in the context of DHA deficiency.
Technically, we can convert a bit of ALA to DHA, estrogen helps, testosterone doesn’t (women have better conversion rates)… and I’d speculate that the reverse is probably easier (DHA –> ALA).