β-Carotene conversion products and their effects on adipose tissue

Recent epidemiological data suggest that β-carotene may be protective against metabolic diseases in which adipose tissue plays a key role. Adipose tissue constitutes the major β-carotene storage tissue and its functions have been shown to be modulated in response to β-carotene breakdown products, especially retinal produced after cleavage by β-carotene 15,150-monooxygenase (BCMO1), and retinoic acid arising from oxidation of retinal. However, the possibility exists that β-carotene in its intact form can also affect adipocyte function. Development of a knock out model and identification of a loss-offunction mutation have pointed out BCMO1 as being probably the sole enzyme responsible for provitamin A conversion into retinal in mammals. The utilisation of BCMO1 ^-/-mice should provide insights on β-carotene effect on its own in the future. In humans, intervention studies have highlighted the huge interindividual variation of β-carotene conversion efficiency, possibly due to genetic polymorphisms, which might impact on response to β-carotene. This brief review discusses the processes involved in β-carotene conversion and the effect of cleavage products on body fat and adipose tissue function.