Fish oil is extracted from the bodies of oily fish whereas cod is a non oily fish that stores oil in its liver. Cod liver oil also contains substantial amounts of vitamins A and D. Cod liver oil has been taken for over 50 years as a source of these vitamins but they become toxic in large excess. Many people now take fish oil so that they can get large amounts of omega-3 fatty acids without risking vitamin overdose. The recommended dose of cod liver oil should not be exceeded and care should be taken if it is taken with other vitamin supplements that also contain vitamin A! Pregnant women should not take any supplement containing vitamin A without the advice of their doctor as high doses can harm their babies.
Two portions of oily fish per week can be safely recommended for anyone and is the most natural way of getting enough omega-3 fatty acids and helping to ensure good intakes of vitamins A and D. Moderate doses of cod liver oil have been safely used for decades and would offer the same benefits for people (especially children) who don’t eat oily fish. If adults are taking supplements to reduce the risk of heart disease or to prevent or treat arthritis then they should probably take fish oil so that they can get good amounts of omega-3 fatty acids without taking excessive amounts of vitamins A and D. Pregnant and breastfeeding women are, like everyone else, advised to eat some oily fish to ensure the proper development of their baby’s brain; in this case small supplements of fish oil (not cod liver oil) may be useful if they don’t eat oily fish.
Oily fish include: sardines, salmon, pilchards, trout, mackerel, fresh tuna and herring
Non oily fish include: cod, haddock and most canned tuna.
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