The association between iron and vitamin D status in Arab adolescents.

Objective: Both vitamin D and Fe micronutrient deficiencies are common in Saudi Arabia but the association between them is unclear. The present study aimed to determine whether Fe indices are associated with vitamin D status and other metabolic markers in Arab adolescents.

Design: Single-centre, cross-sectional study gathering anthropometrics, glucose and lipid profile. Serum 25-hydroxyvitamin D (25(OH)D), Fe, total iron-binding capacity (TIBC), transferrin saturation (%) and other parameters were measured.

Setting: Vitamin D School Project Database, King Saud University (2014-2016).

Participants: Arab adolescents aged 10-17 years randomly selected from the Vitamin D School Project Database (170 Saudi students; 100 girls, seventy boys).

Results: Among Fe indices, only TIBC was found to be significantly and inversely associated with 25(OH)D (r = -0·20; P < 0·01) and only in girls (r = -0·20; P < 0·05). Among cardiometabolic parameters, serum Fe was associated with TAG in boys (r = 0·36; P < 0·01) and inversely associated with HDL-cholesterol in girls (r = -0·29; P < 0·05). Age was the most significant predictor of serum Fe for all participants, accounting for 5 % (R2 = 0·05; P = 0·004) of variance perceived. Serum 25(OH)D and age, on the other hand, were the most significant predictors for TIBC, accounting for 10·1 % (R2 = 0·10; P < 0·001) of variance perceived.

Conclusions: Among healthy Arab adolescents, the association between vitamin D and Fe indices, particularly TIBC, is modest, inverse and sex-dependent. Larger studies with inclusion of markers such as hepcidin and ferritin, vitamin D metabolites and endogenous sex hormones may provide a clearer view of this complex association.