Carotenoids chronic dosing

The measurement of carotenoid absorption is fraught with difficulties and riddled with assumptions, and it is therefore a complex matter. Methods may rely on plasma concentration changes provoked by acute or chronic doses, oral-faecal mass balance method variants and compartmental modelling. 

In contrast to retinoids, carotenoids were considered non-toxic, even when taken chronically in large amounts, until recently, when it was found that ethanol interacts with carotenoids, interfering with their conversion to retinol. In baboons, the consumption of ethanol together with beta-carotene resulted in more striking hepatic injury than consumption of either compound alone (98). This interaction occurred at a total dose of 7.2-10.8 mg of beta-carotene per Joule of diet. This dose is common in people who take supplements and is the same order of magnitude used in the Beta-Carotene and Retinol Efficacy Trial (CARET) (30 mg/day) (99) and in another study (20 mg/day for 12 weeks) (100). The amount of alcohol given to the baboons was equivalent to that taken by an average alcohohc. The well-known toxicity... 

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