Estimation of absorption, retention, and urinary elimination of a single oral high‐dose vitamin A (HD‐VA) supplement or a single oral dose of stable isotope‐labeled (SI‐labeled VA), in 3–4 y old Zambian boys

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A recent survey indicates that HD‐VA supplements have no apparent effect on vitamin A (VA) status of Zambian children <5 y of age. We assessed absorption, retention, and urinary elimination of a single HD‐VA supplement (60 mg), or a smaller dose of SI‐labeled VA (5 mg), used to measure vitamin A pool size, in 3–4 y old Zambian boys (n=8), by co‐administering a tracer dose of 14C‐labeled VA (25 nCi) with the HD‐VA or SI‐labeled VA, and collecting 24‐hr stool and urine for 3 and 7 consecutive days respectively, and 24‐hr urine at 4 later time points.Accelerator mass spectrometry was used to measure the cumulative excretion of 14C in stool 2‐d after dosing to estimate absorption, and in urine 3‐d after dosing to estimate retention. The urinary elimination rate (UER) was estimated by plotting 14C in urine vs. time, and fitting an exponential equation to the data; the 2nd coefficient of the final exponential term was used as an estimate of the UER.Estimated absorption, retention and UER of the HD‐VA supplement were 92.0 ± 5.5%, 84.7 ± 4.9%, and 1.8 ± 1.2 %/d respectively (n=4). Estimated absorption, retention, and UER of the SI‐labeled VA were 88.4 ± 4.6%, 82.2 ± 4.6%, and 1.9 ± 0.5 %/d , respectively (n=4). These estimates did not differ in boys who received the HD‐VA supplement or the smaller dose of SI‐labeled VA