Some of the vitamins that are commonly used by this segment are vitamin B3, vitamin K, vitamin E, and vitamin A and its derivatives, such as retinol, retinaldehyde, oxoretinoids, and retinyl esters
The diet provides retinol as retinyl esters or as provitamin carotenoids, and majority of them are stored within the hepatic lipid droplets (Blaner et al.
CRBP II binds specifically to retinol or retinal, and the CRBP II-retinal and CRBP II-retinol complexes serve as substrate not only for the conversion of retinal into retinol, but also for the conversion of retinol into retinyl esters (Suruga et al.
Topical beta-carotene penetrated well into human and mouse epidermis and induced a 10-fold (human) and a threefold (mouse) increase of epidermal retinyl esters
, which demonstrates that topical beta-carotene is converted into retinyl esters
by human and mouse epidermis and thus appears as a precursor of epidermal vitamin A.
Retinoids allowed for use in cosmetic products include retinol and retinyl esters (for example, retinyl palmitate).
The most likely explanation is the presence of retinyl esters as an impurity in the retinol raw material.
In addition, the concentrations of retinyl esters
after ingestion of a fat-rich meal containing vitamin A have been used as markers of the presence of apo B-48-containing RLPs of intestinal origin.
Anthropometric measurements and blood pressure were assessed upon enrollment, and blood samples were analyzed for the antioxidant nutrients retinol, retinyl esters, carotenoids, vitamin C and vitamin E, as well as glucose, lipids, C-reactive protein, and other factors.
Having higher serum carotenoids or vitamin C was associated with a lower adjusted risk of metabolic syndrome in men and women, while retinol and retinyl esters were associated with a protective effect only in men.
Retinol and retinyl esters
are already present in skin where they account for more than 99% of the total cutaneous retinoids, but retinaldehyde and ATRA are present at the limit of detection.
Heaney referred specifically to a recent study based upon the National Health and Nutrition Examination Survey (NHANES III) data conducted by investigators at the Centers for Disease Control and Prevention (CDC) which found no association between retinyl esters
, a marker of high vitamin A intake, and bone density problems.
Because the former determination is difficult to obtain by immunological techniques due to the identity of apolipoprotein B48 with the amino terminus of apolipoprotein B100 (a marker for lipoproteins secreted by the liver), several investigators have decided to determine retinyl esters
after a fatty meal containing high doses of retinyl palmitate as a marker of chylomicrons and chylomicron remnants (10-15).