Lutein dietary sources

Dietary intake data from a number of studies in North America and the United Kingdom indicate that intake of lutein from natural sources is in the range of 1 to 2 mg/day (approximately 0.01 to 0.03 mg/kg body weight per day). Simulations considering proposed levels of use as a food ingredient resulted in an estimated mean and 90th percentile of intake of lutein plus zeaxanthin of approximately 7 and 13 mg/day, respectively. Formulations containing lutein and zeaxanthin are also available as dietary supplements, but no reliable estimates of intakes from these sources were available. 

The addition of carotenoids to the diet of different animals is commonly used as a method to incorporate certain carotenoids into products that wUl be obtained from such animals. For instance, (3-carotene is added to cattle foodstuff to increase the concentration of provitamin A in milk. In poultry, alfalfa and maize respectively are used as lutein- and zeaxanthin-rich sources, pigments that are incorporated for the pigmentation of the skin and, in particular, egg yolk. The red and yellow coloring of the feathers of certain birds is due to the presence of dietary carotenoids. In the case of salmon, the red color of the flesh is due to pigmentation with dietary astaxanthin and canthaxanthin, which can be introduced artificially in animals bred on fish farms. 

The main dietary carotenoids are lycopene (linear, no substitutions), fl-carotene and a-carotene (ring closure at both ends, no substitutions), P-cryptoxanthin (ring closure at both ends, substitution in the 3 position), lutein (ring closure at both ends, substitutions in the 3 and 3 positions) and canthaxanthin (ring closure at both ends, [O] substitutions in the 4 and 4 positions). In some tissues, particularly flower petals, the hydroxylated carotenoids may also be present as mono- or di-acyl esters, most commonly with C16 fatty acids. Further oxidation of the terminal ring may occur to produce the mono- and di-epoxides. For an exhaustive list of carotenoids, the Key to Carotenoids (Straub 1987) is a recommended reference source. 

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