Vitamin D deficiency in infants is a recognized cause of rickets. Recently, evidence has emerged linking it with lower respiratory tract infections, food allergy, diabetes, schizophrenia and various other extra skeletal health effects. Exclusively breastfed infants are especially vulnerable to vitamin D deficiency due to their dependence on previous trans-placental transfer of vitamin D from the mother, dietary vitamin D from breast milk and cutaneous synthesis of vitamin D on exposure to sunlight. The worldwide epidemic of Vitamin D deficiency in pregnancy and the low content of vitamin D in breast milk underlie the high risk of deficiency in exclusively breastfed infants. Data regarding the magnitude of vitamin D deficiency among exclusively breastfed infants in Kenya is needed to inform supplementation policies.
This study aimed to determine the prevalence of vitamin D deficiency in exclusively breastfed infants and to evaluate its relationship between PTH in this population.
This was a cross sectional study that included three to six month old exclusively breastfed infants at the Aga Khan University Hospital, Nairobi.
Ninety-eight infants were enrolled in the study and their serum 25(OH) D, calcium, phosphate and PTH measured. Data on sunlight exposure and maternal vitamin D supplementation was also collected.
Prevalence of vitamin D deficiency when using 20 ng/ml cut-off, was 24 % (95% CI 14.9%-32.0%). A further 32% of the infants had insufficient levels of vitamin D and 45% of the infants were replete. There were no cases of secondary hyperparathyroidism with vitamin D level above 40ng/ml and one case had an elevated PTH with vitamin D level above 30ng/ml. Using 30ng/ml as the “presumed normal” cut-off for this population, the prevalence of vitamin D deficiency doubled to 55%. Only four mothers received vitamin D supplementation during breastfeeding and all their infants were vitamin D replete. Less than 5% of the study population had skeletal signs of rickets.
Prevalence of Vitamin D deficiency is high in this very young population despite the abundnce of sunshine in this geographical region. A policy on vitamin D supplementation is recommended in this population to mitigate the impact of vitamin D deficiency especially on chronic non-communicable diseases.