I recently heard of a study that concluded that vitamin A was bad for the liver in very high dosages and looking at most fish oils you a substantial amount per capsule. The situation may be of some concern when taking 8-10 a day like myself, anybody have any info on this?
I found this on the Encyclopeida of Human Nutrition in my University’s Database.
Certain types of fish and shellfish are well known as sources of the fat-soluble vitamins A and D; they also can provide significant amounts of some of the B vitamins. Table 5 provides details of the vitamin content of selected fish and shellfish. Vitamin A in the form of retinol is found in large amounts in huss and oysters, as well as in the oil-rich fish such as sprats, herring and mackerel. Eating 100 g of these seafoods would provide around 10-15% of the UK adult reference nutrient intake (RNI) for retinol. The oil-rich pelagic fish are excellent dietary sources of vitamin D3 (cholecalciferol). Though there is no accepted adult RNI for vitamin D, using a value of 10 m g (as may be required for older adults) the oil-rich fish provide 50-200% of such a level per 100 g.
The fish liver oils have much higher levels of the fat-soluble vitamins, and have been used as dietary supplements for over 200 years. The actual levels vary considerably, but halibut liver oil (for example) may contain up to 5000 m g of retinol per gram of oil and up to 120 m g of cholecalciferol. Such levels would be toxic to humans if ingested regularly. Cod liver oil provides generally lower levels, around 100-150 m g of retinol and 1-2 m g of cholecalciferol per gram of oil. Oil used for capsule production tends to be somewhat higher in vitamin concentration, and one capsule (containing 350-500 mg of oil) supplies 100% of the adult RNI for vitamin A. Vitamin E is present in significant amounts in many seafoods, providing around 10-20% of the average daily vitamin E intake of 5-10 mg in a 100 g portion. Since vitamin E requirement is related to the intake of PUFA, it may be considered that the vitamin E present in seafoods is in general sufficient to provide for the additional vitamin E needs that the PUFA content in seafood imposes. However, there is little or no contribution to the vitamin E needs imposed by other dietary sources of PUFA.
Of the water-soluble vitamins, seafoods generally provide little or no vitamin C. The B vitamins are represented to varying extents, with the supply of thiamin, riboflavin and pyridoxine being most significant nutritionally. Consumption of 100 g of most seafoods will supply 10% or more of the adult RNI for these nutrients. Seafoods are especially rich in vitamin B12 , supplying 100% or more of the adult RNI in 100 g.
uh, long and short or it, excessive levels of retinol can cause liver toxicity, but purified fish oils do not contain vit A. Only fish LIVER OILS do. You need not worry.