Retinol, α- and γ-tocopherol and carotenoids in natural and vitamin A- and E-fortified dairy products commercialized in Spain

Natural and added forms of vitamin A (all-trans-retinol, retinyl esters and β-carotene) and vitamin E (α-tocopherol, γ-tocopherol, tocopheryl acetate) were determined in commercially available dairy products that are frequently consumed. Retinyl esters, β-carotene and α-tocopherol are customarily found in natural dairy products, whereas retinyl and α-tocopheryl acetate occur in most vitamin-fortified products. Lutein, zeaxanthin and γ-tocopherol were found in egg- and oil-containing products, respectively. α-Tocopheryl acetate was found in all vitamin-fortified dairy products analysed, whereas retinyl acetate was only present in fluid milks but not in margarines. Minor amounts of retinyl acetate may occasionally be found in some non-fortified milks, suggesting contamination during processing. In commercially available dairy products in Spain, retinyl palmitate and α-tocopherol contents vary substantially, especially in high fat and vitamin-fortified dairy products. Compared with the label claims in vitamin-fortified products, over-fortification predominates, although over- and under-fortification of both vitamins A and E may occur simultaneously in fluid milks. The wide variation observed in commercially available natural and vitamin-fortified dairy products may be an important source of bias and imprecision in nutritional studies.