Serum concentrations of retinol and retinyl esters in adults in response to mixed vitamin A and carotenoid containing meals.

Abstract

Previous studies using spectrophotometric methods for vitamin A analysis concluded that fasting prior to blood collection is not necessary for determining vitamin A status of children or young adult subjects. We measured the effect of mixed vitamin A and carotenoid containing meals with less than 3, 50, and 100% of the recommended dietary allowance (RDA) for vitamin A on serum concentrations of retinyl esters, retinol, and carotenoids in elderly and young adults after an overnight fast. Retinyl ester concentrations rose significantly in both age groups with a numerically higher rise over baseline in the elderly subjects: 6.0 +/- 0.9 micrograms/dl for elderly (p less than 0.001), 5.0 +/- 0.5 micrograms/dl for young (p less than 0.001) at 50% RDA; 9.0 +/- 1.3 micrograms/dl for elderly (p less than 0.001) and 6.8 +/- 1.6 micrograms/dl for young (p less than 0.05) at 100% RDA. We conclude that in both young and elderly adults, but especially in the elderly, fasting conditions are necessary for the accurate assessment of vitamin A status if spectrophotometric methods are used for measuring vitamin A.

Acute effect of dietary stanyl ester dose on post-absorptive α-tocopherol, β-carotene, retinol and retinyl palmitate concentrations

“…Serum retinol concentrations were unchanged after retinol ingestion, a finding observed previously (Rasmussen et al 1991). Retinyl palmitate concentrations rose markedly and similarly in chylomicrons after both test meals, which together with the unaltered triacylglycerol and cholesterol concentrations and AUC suggest that chylomicron formation is not altered by stanyl esters.…”

Plasma levels of retinoids, carotenoids and tocopherols in patients with mild obstructive sleep apnoea

“…It appears that there are cellular mechanisms by which OSA patients have reduced levels of retinoids. Plasma levels of retinyl palmitate may increase after a meal containing a large amount of provitamin A 39 and fasting levels of retinyl ester are significantly increased with the intake of vitamin A supplement 40 . However, since vitamin A (retinol) levels in plasma of both OSA patients and control subjects are similar, differences from controls are not likely due to differences in dietary intake and the specific isomers may be homeostatically controlled.…”