Association between anaemia and vitamin D insufficiency among 6- to 12-month-old infants: implications for clinical practice.

Background: Anaemia and vitamin D insufficiency (VDI) are among the most common nutritional problems. Anaemia screening is routinely performed; however, screening for VDI is not usually recommended.

Objectives: To study the association between anaemia and VDI and identify the risk factors for VDI.

Methods: We conducted a cross-sectional study of 120 infants aged 6-12 months attending a well-child clinic at Songklanagarind Hospital between December 2020 and November 2021. Sociodemographic data and 24-h food records were also collected. Blood samples were obtained for complete blood count and 25-hydroxyvitamin D [25(OH)D] levels. Logistic regression analysis was used to determine risk factors for VDI.

Results: The mean 25(OH)D level was 22.2 ± 8.9 ng/mL in anaemic infants and 27.2 ± 9.6 ng/mL in non-anaemic infants (P value 0.01). The median (IQR) Hb level was 11.1 g/dL (10.3, 11.4) in the VDI group and 11.4 g/dL (11, 12.1) in the non-VDI group (P value 0.002). The proportion of breastfed infants was higher in infants with anaemia (80%) (P < 0.001) and VDI (85.3%) (P < 0.001). Sunlight exposure <15 min/day (odds ratio [OR] 3.84; 95% confidence interval [CI]: 1.23-12.00; P = 0.020) was a risk factor, and vitamin D intake (OR 0.37; 95% CI: 0.20-0.74; P = 0.004) was a protective factor for VDI.

Conclusion: Infants with anaemia, short duration of sunlight exposure, breastfeeding, low vitamin D intake, and low iron intake were more likely to be vitamin D insufficient. However, after adjustment in the multivariate analyses, only sunlight exposure and vitamin D intake were significantly associated with vitamin D insufficiency.