Lee Swanson Research Update

Urinary Tract Health Gets Boost from Vitamin D

January 2011

Adequate vitamin D levels may boost the body’s immune response and protect against urinary tract infections, says a study from Sweden.

Vitamin D supplementation was found to promote production of an anti-microbial peptide called cathelicidin in the urinary tract, thereby offering local and site-specific protection, according to findings published in Public Library of Science One (PLoS ONE).

"This could make [25-hydroxyvitamin D3 (25D3)] an effective and safe way of activating the endogenous anti-microbial response locally at the site of infection," wrote researchers from the Karolinska Institutet and Karolinska University Hospital in Stockholm. "Determining the vitamin D status of individuals with a history of UTI may be of importance to evaluate their ability to fend off intruding bacteria.

"Supplementation to restore proper vitamin D levels may therefore help in preparing the bladder epithelium to mount a stronger and faster immune response once bacteria enter the bladder."

The new study indicates that the benefits of the sunshine vitamin may extend to urinary tract health—a health category traditionally dominated by cranberry juice and extracts.

The Stockholm-based scientists analyzed vitamin D blood levels in 22 postmenopausal and six pre-menopausal Swedish women. An additional eight women with a median age of 62 were recruited to participate in a supplementation trial (2,000 units per day of 25D3 for 12 weeks). Five women completed the trial.

The Swedish researchers note that 1,25(OH)2D was measured in bladder cell cultures, which indicated that the cells of the bladder are capable of producing the active form of the vitamin.

Results from the supplementation trial showed that 25-hydroxyvitamin D3 was associated with an induction in the expression of cathelicidin when bladder biopsies were exposed to E. coli. No general induction of the anti-microbial peptide was observed during vitamin D supplementation, added the researchers.

"Here we show that oral 25D3 supplementation of healthy postmenopausal women prepares the bladder tissue to fight E. coli infection by increased production of cathelicidin upon bacterial contact," report the researchers. "25D3 is locally converted to 1,25D3 in bladder epithelial cells, binds to vitamin D receptors, which leads to […] synthesis of cathelicidin.

"The increased production in turn enhances the direct antibacterial effect on uropathogenic E. coli," they added.

"In light of the emerging resistance to antibiotics used against UTI, new treatment strategies are needed," report the researchers. "Our data suggest that vitamin D can stimulate an increased production of the anti-microbial peptide cathelicidin. By inducing and activating cathelicidin with vitamin D, a local rather than a systemic effect can be achieved. This could offer selective and site-specific treatment of pathogens without perturbing commensal microbes elsewhere in the body."

PLoS ONE 5(12):e5580, 2010

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