The problem with taking fish oil supplements is that even in the presence of adequate E, any EPA and DHA taken without adequate vitamin A (real preformed A, not beta carotene) elevates lipid peroxide levels. OTOH, a clean, high-vitamin cod liver oil is a vastly superior source of omega 3s because depending on which study you look at, CCLO either actually depresses lipid peroxide levels or at least doesn't elevate them.
Interesting. I've been looking for a source of vitamin A as well as my diet does not include any food that are fortified with it. And the vitamin D won't hurt either.
What is you opinion on a high quality fish (not cod) oil, taken with a bevy of antioxidant supplements? That is what I currently do.
Depends on what antioxidants you're taking. Different ones have different functions in the body, and both sufficient E
and A are required to prevent PUFA oils from raising lipid peroxide levels. I take a bunch of different antioxidants too, but I make sure to get plenty of A and D. Here's an excerpt from an
excellent article a friend of mine wrote which touches on the subject.
While antioxidants protect against lipid peroxidation, consumption of polyunsaturated fatty acids (PUFA) raises lipid peroxides. PUFA levels can be low on a vegetarian diet if oils like olive oil or saturated coconut oil are staples, but cod liver oil, an animal product, is the only polyunsaturated oil that has been shown to provide essential fatty acids without raising lipid peroxide levels.
Polyunsaturated plant oils rich in essential fatty acids such as soybean oil,52 corn oil53 and the omega-3-rich perilla oil54 all raise lipid peroxide levels. It is not only heated polyunsaturated oils that raise lipid peroxides. Even fresh, unoxidized perilla oil stored at –20C and fresh, unoxidized, purified DHA and EPA—the omega-3 PUFAs found in fish oil and cod liver oil,—stored at –80C, mixed into the diets of rats immediately before feeding, raised lipid peroxide levels in tissues considerably—even when rats were fed adequate vitamin E.54
Cod liver oil, on the other hand, has been shown to inhibit lipid peroxidation. One study found that cod liver oil depressed drug-induced lipid peroxidation in mice under the same conditions by which soybean oil increased lipid peroxidation.52 Another study found that feeding cod liver oil entirely abolished the increased level of lipid peroxidation found in diabetic rats.55 In both studies, the depression of lipid peroxidation was related to a sparing effect on glutathione peroxidase activity, which was also the case in rats saved from a lethal dose of dioxin by vitamin A supplementation, suggesting that the protective effect of cod liver oil is due to its high vitamin A content.
And the relevant citations.
52. Ohtake, et al., "Effects of dietary lipids on daunomycin-induced nephropathy in mice: comparison between cod liver oil and soybean oil," Lipids, Vol. 37 No. 4 (2002) 359-366.
53. Diniz, et al., "Diets rich in saturated and polyunsaturated fatty acids: metabolic shifting and cardiac health," Nutrition, 200 (2004) 230-234. ff
54. Saito and Kubo, "Relationship between tissue lipid peroxidation and peroxidizability index after a-linolenic, eicosapentaenoic, or docosahexaenoic acid intake in rats," British Journal of Nutrition, 89 (2003) 19-28.
55. Hunkar, et al., "Effects of cod liver oil on tissue antioxidant pathways in normal and streptozotocin- diabetic rats," Cell Biochem Funct. Vol. 20 No. 4 (2002) 297-302.
Unless you have some specific reason for avoiding high-vitamin CLO, I'd recommend CLO over fish oil.