Prevalence and Correlates of Vitamin D Deficiency among Young South African Infants: A Birth Cohort Study

Abstract

Early-life vitamin D deficiency is associated with adverse child health outcomes, but the prevalence of vitamin D deficiency and its correlates in infants remains underexplored, particularly in sub-Saharan Africa. We aimed to investigate the prevalence of vitamin D deficiency and its correlates among young infants in South Africa. This study included 744 infants, aged 6–10 weeks from the Drakenstein Child Health Study, a population-based birth cohort. Infants were categorized into distinct categories based on serum 25(OH)D concentration level including deficient (<50 nmol/L), insufficient (50–74 nmol/L), and sufficient (≥75 nmol/L). Using multivariable Tobit and logistic regression models, we examined the correlates of serum 25(OH)D3 levels. The overall prevalence of vitamin D deficiency was 81% (95% confidence intervals (CI]) 78–83). Multivariable regression analysis showed that serum 25(OH)D3 concentration was independently associated with study site, socioeconomic status, and sex. Birth in winter and breastfeeding were the strongest predictors of lower serum 25(OH)D3 concentration levels. Compared to non-breastfed children, children breastfed were at higher risk of vitamin D deficiency (AOR, 1.96; 95% CI, 1.04–3.67) and breastfeeding for more than one month was associated with greater likelihood of vitamin D deficiency (AOR, 5.40; 95% CI, 2.37–12.32) and lower vitamin D concentrations (−16.22 nmol/L; 95% CI, −21.06, −11.39). Vitamin D deficiency in infants is ubiquitous, under-recognised, and strongly associated with season of birth and breastfeeding in this setting. Nutritional interventions with vitamin D supplementation in national health programs in low- and middle-income countries are urgently needed to improve early-life vitamin D status in infants.

Vitamin D Concentrations in Infancy and the Risk of Tuberculosis Disease in Childhood: A Prospective Birth Cohort in Cape Town, South Africa

“…The study cohort as well as the subcohort tested for vitamin D has been described previously [ 3 , 14 , 15 ]. Briefly, we enrolled pregnant women between 20 and 28 weeks’ gestation attending antenatal care in Paarl, a periurban setting outside of Cape Town, South Africa.…”

“…Data were collected on infant factors relevant to vitamin D and tuberculosis disease risk based on prior studies with this cohort [ 3 , 15 ] as well as the medical literature [ 18 ]. Infant variables included sex, height-for-age z score (HAZ), weight-for-age z score (WAZ), maternal HIV, gestational age, breastfeeding practices in the first year of life, and season of birth.…”

“…To assess whether there was a dose–response relationship between vitamin D concentration, we categorized vitamin D concentrations into tertiles, as used elsewhere and to enable comparison with such studies [ 11 , 12 , 15 ]. We compared incident tuberculosis disease among participants at each tertile level.…”

“…We assessed the odds of a tuberculin conversion at 1 year of age or younger or 2 years of age independently for each vitamin D deficiency cutoff and in each vitamin D tertile. Multivariable models were built including all relevant variables related to tuberculin conversion in this cohort [ 3 , 15 ]. All analyses were performed using Stata (version 14.1; StataCorp, College Station, TX, USA).…”

Association Between Vitamin D Level and Neonatal Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

“…Neonates with younger gestational age tend to suffer from a higher incidence rate, lighter weight, and a higher fatality rate (3). Vitamin D is a fat-soluble steroid derivative that plays very important physiological functions in the human body (4), namely improving the body's absorption of calcium and phosphorus, promoting growth and bone calcification (5), and regulating the body's immune function (6). With more and more in-depth research at home and abroad in recent years, many animal and laboratory studies have found that the lack of vitamin D is also involved in the occurrence of respiratory diseases in children (7)(8)(9).…”