In Cystic Fibrosis Patients, Vitamin D Supplements Might Not Prevent Deficiencies

A new study entitled “Vitamin D and Chronic Lung Colonization in Pediatric and Young Adult Cystic Fibrosis Patients” published in the Spanish-language journal Nutrición Hospitalaria, investigated vitamin D levels in the body and its association with chronic lung colonization. The study showed that vitamin D supplements did not improve the vitamin’s insufficiency in young cystic fibrosis patients.

Cystic fibrosis (CF) is a frequently inherited genetic disorder in the Western world, and most CF patients develop respiratory failure due to chronic pulmonary infection. Several factors, including environmental, nutritional, and socioeconomic, may affect the clinical manifestations of cystic fibrosis. Low levels of vitamin D are highly prevalent in CF patients, likely due to the combination of inadequate nutrient absorption, impaired metabolism, and lack of sun exposure. Vitamin D insufficiency is associated with high incidence of bone disease or osteoporosis in CF patients.

In this study, researchers evaluated vitamin D levels in serum samples from 377 cystic fibrosis patients whose ages ranged from 2 months to 20 years. The patients, from several university hospitals in Spain, were evaluated over the course of two years. The researchers found that younger patients had lower levels of vitamin D as well as a higher number of pathogen colonizations. They showed that despite CF patients receiving vitamin D supplements — which are currently recommended for the disease — a high percentage showed insufficient levels of the vitamin. Moreover, they found that age, pancreatic function, type of diagnosis, and lung colonization modulate the levels of serum vitamin D in these patients. Regardless of age, diagnosis by screening or pancreatic status, chronic colonization by Pseudomonas aeruginosa in children and adolescents and by Staphylococcus aureus in infants and preschoolers increased their risk of developing vitamin D deficiency.

The authors, however, are aware of the limitations of their study.  The longitudinal nature of the study makes impossible to know whether vitamin D levels are the cause or consequence of chronic lung colonization in these patients. The multicenter nature of the study, while necessary to obtain a sample size sufficient in low-prevalence diseases as CF, could introduce biases when analyzing the dose and vitamin D levels due to lack of vitamin supplement standardization protocol among the centers. However, all patients received vitamin D doses as expected. The clinical centers were from different latitudes, but the sera vitamin D were collected during the same time period (fall-winter), decreasing but not eliminating the modifying effect of sun exposure on vitamin D levels.

These findings could encourage additional studies into the interplay of vitamin D, cystic fibrosis, and bacterial infections. New discoveries might help physicians develop new best practices for supplements that could better optimize vitamin D levels in CF patients.