Background: The variable response to fat-soluble vitamin supplementation in young children with cystic fibrosis (CF), and factors contributing to this variability, remain under-investigated.
Objective: To determine if recommended supplement doses normalize serum vitamins A (retinol), D (25-hydroxy-vitamin D, 25OHD), and E (α-tocopherol), and identify factors predictive of achieving sufficiency, in children with CF in the first 3 years of life.
Design: We studied 144 infants born during 2012-2017 and diagnosed with CF through newborn screening. Serum retinol, 25OHD, α-tocopherol and plasma cytokines interleukin (IL)-6, IL-8, IL-10, and tumor necrosis factor (TNF)-α were measured in early infancy and yearly thereafter. Vitamin supplement intakes and respiratory microbiology were assessed every 1-2 months in infancy and quarterly thereafter.
Results: The prevalence of vitamin D insufficiency (<30 ng/ml) at all ages combined was significantly higher (22%) compared to vitamin A (<200 ng/ml, 3%) and vitamin E (<5 µg/ml, 5%). All children were vitamin A sufficient by age 2 years. Vitamin E insufficiency was rare. Only 42% were early responders of vitamin D and 17% remain insufficient despite high supplement intakes. IL-6 was positively correlated, while IL-8, IL-10, and TNF-α were negatively correlated, with retinol and 25OHD. Multiple regression analysis revealed that supplement dose, season, α-tocopherol, pancreatic insufficiency, respiratory infections and IL-10 were significant predictors of 25OHD.
Conclusion: Diagnosis through newborn screening coupled with supplementation normalized serum retinol and α-tocopherol in almost all infants with CF by age 3 years. However, response to vitamin D supplements in young children with CF occurred later and variably despite early and sustained supplementation.
Keywords: 25-hydroxyvitamin D; children; cystic fibrosis; fat-soluble vitamins; infection; inflammation; vitamin A; vitamin D; vitamin D supplementation; vitamin E.
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