Lower respiratory tract infection, also known as pneumonia, is an infection that inflames air sacs in one or both lungs, potentially leading to the lungs filling with fluid. Symptoms include cough with phlegm, fever, chills and difficulty breathing. Pneumonia affects nearly 120 million children worldwide annually and accounts for 1.8 million deaths in children under the age of five annually.
Research has found that most respiratory infections during winter have been reported when sun exposure is the least available and therefore, vitamin D production is lowest. Furthermore, studies have discovered a correlation between lighter skin pigmentation and fewer acute respiratory infections. Scientists believe that vitamin D’s vital role in the immune system is responsible for these findings.
In a recent meta-analysis, Dr. Kana Ram Jat hypothesized that vitamin D deficiency is a risk factor for the development of pneumonia in children. The meta-analysis evaluated 12 observational studies: 3 cohorts, 2 cross-sectional and 7 case control studies on the relationship between vitamin D status and pneumonia in children.
Here is what Dr. Jat found:
- Of the 2,279 children, 29.7%, 21.1% and 37.0% were considered vitamin D deficient, vitamin D insufficient and vitamin D sufficient, respectively.
- Children with pneumonia were over three times as likely to be vitamin D deficient in comparison to healthy controls.
- Children with pneumonia had significantly lower vitamin D levels than healthy children, with an average difference of 3.5 ng/ml.
- There was a 13-fold higher prevalence of rickets in children with pneumonia than in healthy children (p < 0.001).
- One cohort revealed that there was significantly more treatment failure in children with very severe pneumonia who had rickets as compared to children without rickets (OR 1.38, 95% CI 1.13-1.69, p = 0.031).
- A study from Japan found a significant association between vitamin D deficiency and need for supplementary oxygen and ventilator management in children admitted with pneumonia.
Dr. Jat concluded,
“Mean vitamin D levels were lower in children with LRTI compared to controls.”
She went on to state,
“[Pneumonia] is responsible for considerable under-5 mortality in children, therefore if correction of vitamin D deficiency by supplementation has indeed a significant impact on prevention and treatment, such a simple intervention would be a major public health measure.”
The strengths and limitations of this meta-analysis go hand in hand. The study consisted of a large number of participants, which increases the validity and power of the findings. Though, its main limitation rests in the heterogeneity (differences) of the included studies.
The study summarizes current research evaluating the relationship between vitamin D status and pneumonia in children, and in doing so, leads us to wonder if widespread vitamin D supplementation will reduce the risk of pneumonia and death in children. However, one cannot answer this question until a large randomized controlled trial (RCT) with adequate daily dosing for a long duration is conducted.
The problem with doing a large RCT to see if vitamin D prevents childhood pneumonia is that the scientists would have to have a placebo group that are identified as deficient and kept deficient for the course of the study. More and more university ethics committees are finding that to be unethical.
Tovey, A. & Cannell, JJ. New meta-analysis finds vitamin D children with pneumonia have significantly lower vitamin D levels. The Vitamin D Council Blog & Newsletter, 2016.