We actually like high-quality cod liver oil as a dietary supplement, but since our website focuses on food, we did not profile cod liver oil on the site. As you may already be aware, we try to avoid heating oils when cooking, because we believe that there is too much nutrient loss and too many other risky changes that take place when heating oils. If someone insisted on cooking with oils, cod liver oil would be one of the last oils we would recommend for stir-frying or other uses, because it has some of the highest concentrations of delicate omega-3 fatty acids that would get damaged during high temperature cooking.
On the supplement side of things, cod liver oil is usually sold in soft gel capsules, containing about 500-1,000 milligrams of oil per capsule. A 1,000 milligram capsule will usually contain about 100-125 milligrams of DHA (the long-chain omega-3 fatty acid that's so important in our brain and nervous system) and about 50-75 milligrams of EPA (another omega-3 fatty acid that's especially important in cell membrane function and cardiovascular health). There's also a good bit (about 200-250 milligrams) of oleic acid (a monounsaturated fatty acid) per capsule. This combination of omega-3s and monounsaturates makes cod liver oil a fairly unique type of supplement, and there are many circumstances when it would make sense to include it as part of a supplemental regimen. Although a capsule of cod liver oil contains a fairly small amount of vitamin D (three 1,000-milligram capsules would only provide you with about 3-10% of the RDA), it contains a higher amount of vitamin A. In the case of vitamin A, three 1,000-milligram capsules would provide you with about 15-30% of the RDA amount.
Whether you need to take cod liver oil as a supplement depends on your current, individual nutrient needs and the overall composition of your diet. It's definitely incorrect to think about cod liver oil supplements as a replacement for cooked fish on your dinner plate. There are many nutrients present in the fish that are totally absent from the supplement. For example, if the protein found in your fish is an important part of your daily protein intake, replacing the fish with the supplement will leave you with far too little daily protein. It can sometimes be complicated to figure out exactly what dietary supplements you do and don't need, and for this reason we often recommend consulting with a healthcare professional with extensive experience with whole, natural foods and meal planning.
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