The Journal of Nutrition · 8 authors, 4 centres
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Using compartmental modeling and retinol isotope dilution, total body vitamin A stores were found to be similar in 22 young people with sickle cell disease (HbSS) and 20 healthy peers despite lower plasma retinol in the SCD group. Eight weeks of daily vitamin A supplementation at doses up to 2.6 times the Recommended Dietary Allowance did not significantly increase total body stores in the SCD subjects.
This study used population-based compartmental modeling of composite plasma [13C10]retinol response data and retinol isotope dilution (RID) to quantify vitamin A total body stores (TBS) and retinol kinetics in 22 young people with SCD-HbSS, 20 healthy peers, and the SCD-HbSS subjects after 8 weeks of daily vitamin A supplementation. Model-predicted group mean TBS for SCD-HbSS subjects was 428 μmol, and RID-predicted TBS at 3 d postdosing was 389 μmol; mean TBS in healthy peers was 406 μmol, with no significant differences between groups. RID-predicted TBS was not significantly affected by vitamin A supplementation at either dose. The model predicted that 92% of total body exchangeable vitamin A was in the larger extravascular pool. Limitations include small sample sizes, the absence of kinetic studies after intervention or in healthy subjects, and the use of SCD-HbSS-derived FaS values for RID predictions in healthy peers. These findings indicate that despite suboptimal plasma retinol concentrations, vitamin A stores were adequate and comparable to healthy peers, and short-term supplementation did not increase stores.
