The prevalence of respiratory tract infections (RTIs) and chronic cough in children is widespread and accounts for a large number of paediatrician visits each year. In a 2016 prospective observational study, low serum vitamin D levels were linked with an increased frequency in these conditions, while supplementation reduced the symptoms and frequency by over 50%.
Infants aged 6-86 months were included in this one-year study. Researchers compared the serum vitamin D levels of 98 children with recurrent RTIs, 101 children with chronic cough and 124 healthy symptom-free children.
The children in the RTI and chronic cough groups had deficient mean serum vitamin D levels (11.9ng/mL or 29.7nmol/L and 13.7ng/mL or 34nmol/L, respectively). Whereas, the control group had normal mean levels of 31.9mg/mL (79nmol/L). From their analysis, the researchers showed vitamin D deficiency was associated with increased RTI and chronic cough frequency.
Serum vitamin D levels above 20mg/mL (49nmol/L) were classed as normal, 15-20mg/mL (37-49nml/L) as insufficient, below 15ng/mL (37nmol/L) as deficient and below 5ng/mL (12.5nmol/L) as severely deficient.
Both treatment groups with serum levels lower than 15ng/mL (37nmol/L) were then given 5000IU of vitamin D3 per day for 3 months. Those with levels higher than this received 400IU per day.
At the six-month follow up, the frequency and symptoms in the RTI group decreased by 67.3%; in the chronic cough group there was a 58.4% reduction.
The authors concluded ‘significantly low serum 25(OH)D levels were found in children with RTI and chronic cough. Co-administration of supplementary vitamin D of 5000IU/day for 3 months, together with conventional treatments, may be appropriate in the prophylaxis of RTI and chronic cough. The simple intervention of vitamin D supplementation appears promising in helping to prevent infections and chronic cough in children.’
This effect is not only seen in children, with a recent study analysis showing vitamin D supplementation of 4000IU per day reduced RTI recurrences in susceptible adults, providing a safe and inexpensive therapy. Interestingly, the benefits were seen after 3 months of supplementation, which corresponded with increased serum vitamin D levels, ‘thus strengthening a relationship between 25-OH vitamin D levels and RTIs.’
- Ozdemir B, Koksal BT, Karakas NM, et al. Serum vitamin D levels in children with recurrent respiratory infections and chronic cough. Indian J Pediatr 2016 Jan [Epub ahead of print] [Full Text]
- Bergman P, Norlin AC, Hansen S, et al. Vitamin D supplementation to patients with frequent respiratory tract infections: a post hoc analysis of a randomized and placebo-controlled trial. BMC Res Notes 2015;8:391. [Full Text]