Vitamin D deficiency appears to be more common in children with recurrent UTI, and vitamin D supplementation significantly increased serum vitamin D levels and was associated with a reduction in recurrent UTI frequency based on a pre-post comparison within the patient group.
Key Findings
Results
Vitamin D deficiency was significantly more prevalent in children with recurrent UTI compared to healthy controls, despite mean serum levels not differing significantly between groups.
Mean serum vitamin D levels in the patient group were 15.89 ± 6.76 ng/mL vs. 19.96 ± 10.08 ng/mL in controls, a non-significant difference (p = 0.16)
Vitamin D deficiency prevalence was 88.9% in the patient group vs. 36.8% in the healthy control group (p = 0.002)
The study included 18 school-aged children with recurrent UTI and 19 healthy children in a prospective case-control design
Results
Vitamin D supplementation significantly increased serum vitamin D levels in children with recurrent UTI.
Serum vitamin D levels increased from 15.89 ± 6.76 ng/mL before supplementation to 19.96 ± 8.77 ng/mL after supplementation (p = 0.04)
The proportion of patients with vitamin D deficiency decreased significantly from 88.9% to 38.9% following supplementation (p = 0.004)
Pre-post comparison was conducted within the patient group of 18 children
Results
The median number of UTI episodes declined significantly in children with recurrent UTI following vitamin D supplementation.
The median number of UTI episodes declined from 2.0 to 1.5 episodes (p = 0.014)
This finding is based on a pre-post comparison within the patient group
No control group comparison for UTI episode frequency was reported
Conclusions
The authors concluded that correcting vitamin D deficiency may be a simple and effective method for preventing recurrent UTI in school-aged children.
The study design was a prospective case-control study with a within-group pre-post supplementation comparison
The study was registered in 2021 (registration number 2021/605, 09.09.2021)
The sample sizes were small: 18 children in the patient group and 19 in the healthy control group
What This Means
This research suggests that children who experience repeated urinary tract infections (UTIs) are much more likely to have low vitamin D levels compared to healthy children — nearly 89% of children with recurrent UTIs had vitamin D deficiency, versus about 37% of healthy children. Importantly, average vitamin D blood levels were similar between the two groups, meaning the difference was driven by how many children fell below the deficiency threshold rather than the average level alone. When children with recurrent UTIs were given vitamin D supplements, their blood vitamin D levels rose significantly, the proportion with deficiency dropped from about 89% to 39%, and the number of UTI episodes they experienced declined from a median of 2.0 to 1.5 episodes.
This research suggests there may be a link between vitamin D status and susceptibility to recurrent UTIs in children, possibly because vitamin D plays a role in supporting the immune system's ability to fight infections in the urinary tract. However, the study is small — with only 18 children in the UTI group and 19 healthy children — and the reduction in UTI episodes, while statistically significant, was modest. There was no placebo control group for the supplementation phase, so it is difficult to rule out other factors contributing to the change in UTI frequency.
This research suggests that checking vitamin D levels in school-aged children with recurrent UTIs and addressing deficiency through supplementation could potentially be a straightforward supportive strategy worth further investigation in larger, controlled trials.
Check Your Own Numbers
Upload your bloodwork. We'll cross-reference your results against this study and 4,700 others.
Özçift B, Kantar A. (2026). Is vitamin D the missing link in recurrent urinary tract infections in children? A prospective study.. World journal of urology. https://doi.org/10.1007/s00345-026-06509-8