Predictors of vitamin D status in undernourished and well-nourished children 6-59 months-old, in the JB Marks municipality of South Africa

Abstract

Objective: to investigate the predictors of vitamin D (vitD) status of undernourished and well-nourished children aged under five years in the North West Province of South Africa.
Design: this cross-sectional study assessed sociodemographic data, nutritional supplement intake, vitD-rich food consumption, and sunlight exposure via a structured questionnaire. Venous blood samples were collected to evaluate vitD, iron, and inflammatory markers.
Setting: the maternal and child wellness departments of six community clinics in the JB Marks Municipality.
Participants: 121 undernourished and 51 well-nourished children, 6–59 months old.
Results: The prevalence of serum 25(OH)D < 30 ng/ml was 20.3%, 19.9%, and 21.6% in the total, undernourished, and wellnourished groups, respectively. The total mean 25(OH)D concentration was 38.41 ± 9.64 ng/ml. Age showed a negative association trend with 25(OH)D in the well-nourished group (β: −0.172, 95% CI −0.353, 0.010, p = 0.063), while household income was inversely associated with 25(OH)D (β = −1.86, 95%CI = −2.99, −0.733, p = 0.001) in the total group. Among the undernourished children, iron-deficiency anaemia (IDA) was associated with almost five times greater odds for 25(OH)D < 30 ng/ml (OR: 4.646, 95% CI 1.339, 16.123, p = 0.016). Intake of vitD supplements, therapeutic foods, multivitamins, and formula milk was associated with significantly higher 25(OH)D concentrations and was adjusted for in subsequent analyses. Additionally, consumption of eggs more than once a month was associated with higher 25(OH)D levels in the wellnourished children aged 24–59 months. Nutritional status, inflammation, and sunlight exposure were not associated with
25(OH)D concentrations.
Conclusion: vitD insufficiency exists in both the undernourished and the well-nourished. Age, egg consumption, and IDA should be considered in the correction of vitD insufficiency in children.
Trial registration: Pan African Clinical Trial Registry identifier: PACTR202110646172601.