No improvement in suboptimal vitamin A status with a randomized, double-blind, placebo-controlled trial of vitamin A supplementation in children with sickle cell disease

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3441116/pdf/ajcn964932.pdf



Vitamin A is an essential nutrient in humans required for immune function, growth, development, reproduction, and vision (1). The adverse health effects of vitamin A deficiency (serum retinol <20 μg/dL) are numerous, including an increased risk of morbidity and mortality, reduced resistance to infection, impaired cellular differentiation, and higher rates of anemia, xerophthalmia, and blindness (2). In US children with type SS sickle cell disease (SCD-SS)4, suboptimal vitamin A status (serum retinol <30 μg/dL) is prevalent and is associated with increased hospitalizations and poor growth and hematologic status (3). In addition, the adequacy of vitamin A dietary intake declines with age in children with SCD-SS (4). Collectively, these data suggest that vitamin A supplementation is necessary throughout childhood in those with SCD. However, no study has investigated the supplemental vitamin A dose needed to optimize vitamin A status in this population.


Subjects with SCD-SS aged 2.0–12.9 y were recruited in Pennsylvania from the Sickle Cell Center at The Children's Hospital of Philadelphia (CHOP) and Lehigh Valley Hospital and in New Jersey from the CHOP Voorhees Specialty Care Center and Newark Beth Israel Medical Center. Exclusion criteria included chronic transfusion therapy or a transfusion within the past 2 mo, hydroxyurea therapy, history of stroke, liver enzymes >3 times the reference range, height >2.0 SDs above the age and sex mean (>98th percentile, CDC 2000 reference standards; 5), participation in another intervention study, pregnancy, and other chronic conditions known to affect growth, dietary intake, or nutritional status. In addition, subjects taking daily vitamins or commercial nutritional supplements containing vitamin A were not eligible for the study. However, subjects willing to discontinue supplementation with the approval of their medical care team were eligible after a 2-mo washout period.

Study design

All subjects completed a screening visit, and, if eligible, baseline and 3-, 6-, 9-, and 12-mo visits. The initial recruitment date was 16 November 2004. Before the screening visit, a chart review was completed to document an SCD-SS diagnosis based on electrophoresis and to conduct a preliminary assessment of other inclusion and exclusion criteria. Those eligible completed a screening visit to assess vitamin A; hematologic, hepatic, and inflammatory status; dietary intake; height; and weight. Those meeting all inclusion criteria were invited to participate in the vitamin A supplementation trial. To account for variability, those with a screening serum retinol concentration <34.5 μg/dL were invited to complete a baseline visit. At baseline, all subjects had a serum retinol concentration <30 μg/dL, defined as suboptimal vitamin A status for this study.

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