LETTER TO THE EDITOR – MARCH 1999

In the article on vitamin A and bone mineral density, a figure of 7500 IU of vitamin A is given. Does this mean real vitamin A (from animal sources such as fish oil) or does it include beta- carotene (from vegetable sources which is metabolized into vitamin A in the human body)? If even beta-carotene is a problem, is there some equivalent ratio (such as 2 beta-carotene = 1 IU of vitamin A) or does the IU measurement already take this into account (1 IU beta-carotene = 1 IU vitamin A)?

Peter S., Princeton, NJ

Editor: The vitamin-A intake reported in the abstract was mainly from cod liver oil; however, margarine and low-fat milk products are also fortified with vitamin A in Sweden. No increased risk for hip fracture was found even at the highest intakes of beta-carotene; this is perhaps not surprising as beta- carotene is only converted to vitamin A as needed. Vitamin A activity is measured in Retinol Equivalents (RE) with 1 mg of pure vitamin A corresponding to 1000 RE or 5000 IU. In theory it takes 6 mg of beta-carotene to equal 1 mg of vitamin A so 5000 IU of vitamin A equals 30,000 IU of beta-carotene.