Chris Kresser: I don’t think they’re necessary. As you may know, I’m not sure where we’re at in the nutrition/exposome part of the course, but I don’t often recommend supplementing with fish oil unless you include cod liver oil in that. I recommend eating whole fish because of all the other nutrients that it contains above and beyond the oil, low-mercury species of cold-water fatty fish, and then if you’re not eating organ meat, then some cod liver oil for vitamin A primarily, although it has some D and EPA and DHA. I think that that’s a recommendation that’s safe for virtually all of our patients regardless of what their long-chain fatty acid test results would suggest.
Having said that, if you do want more information about those levels, there are a number of different labs that offer that. The main way that we get it is through the True Health Diagnostics panel, which is a very advanced lipid and metabolic marker panel, and they include the omega-6-to-omega-3 ratio. The Omega Index, I think, is what it’s called. It’s a test that was created by Bill Harris, I believe, who has done a ton of research in that area. I would say that most of the patients that get that test come back with a borderline result. Maybe 50 to 60 percent have what they call a borderline result, so the omega-3-to-omega-6 ratio is not low, but it’s not in the optimal range. Then another maybe 20 to 30 percent have optimal range, and then for another 10 to 20 percent, it’s actually low. That tells me that most people probably can benefit from eating more fish and less omega-6 industrially processed seed oil, but there are some concerning studies which I’m written about on my blog about high-dose omega-3 or fish oil supplementation over a long period of time, which makes me feel a lot safer recommending fish consumption with a small, moderate dose of cod liver oil.