For most omnivores, the aggregate omega-3:omega-6 ratio, which will be dominated by the shorter chain alpha-linoleic acid (ALA) and linoleic acid (LA), is probably misleading. The immediate precursors competing for conversion to signaling eicosanoids are the longer chain eicosapentanoic acid (EPA) and arachidonic acid (AA), and as males and post-menopausal women have little elongase activity converting ALA to EPA and LA to AA, their effective balance of these long-chain precursors will be largely dictated by their dietary intake of EPA and AA, rather than that of the shorter essential fatty acids. Premenopausal women (as well as male-to-female transexuals taking estrogen) have much more elongase activity, presumably to ensure adequate EPA, DHA, and AA for pregnancy and lactation.
Practically, all dietary EPA and AA will be from animal products, with EPA dominating the balance of the two in wild caught cold-water fish, a rough balance in grass-finished meats, and AA dominating in all other animal products due to grain feeding in modern animal agriculture. From the limited elongase perspective, pescetarian diets focusing on wild caught cold-water fish (with no other animal products) appear the most attractive option for ensuring a high EPA:AA ratio.
See also:
Personally, I eat no animal products, avoid high LA refined oils and processed foods that contain them, and take a high-potency EPA+DHA supplement. My pool of eicosanoid precursors is dominated by EPA. And health wise, I'm fine, and seem to experience fewer systemic inflammation related symptoms (from sore joints to ED/aka mid-stage atherosclerosis) than others my age. I believe the inflammatory tone of our innate immune system that was adaptive when parasites and open wound trauma were commonplace is overkill in our more hygenic and less violent modern state.
Edited by Darryl, 08 February 2016 - 05:45 PM.