February 4th, 2011
By: S.L. Baker
Besides protecting from cancer, obesity, autoimmune diseases and cardiovascular problems, vitamin D helps build strong bones. And scientists have found this health building vitamin has a remarkable impact on the immune system, too. Vitamin D, it turns out, is necessary for the production of anti-microbial peptides, substances that fight off infection-causing bacteria, fungi, and viruses when these pathogens try to move into organs and through mucous membranes.
In fact, previous research has shown adequate vitamin D can help prevent colds and flu as well as serious lung infections, including tuberculosis. Now Swedish researchers from the Karolinska Institute and Karolinska University Hospital in Stockholm have evidence that higher vitamin D levels offer especially strong protection against another common health problem — urinary tract infections (UTIs).
In their new study, just published in the journal PLoS One, the scientists wrote: “In the light of the rapidly growing problem of resistance to common urinary tract antibiotics, we suggest that vitamin D may be a potential complement in the prevention of UTI. 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.”
The research team pointed out that the urinary tract is frequently exposed to infection-causing agents and has a built-in, rapid defense system. When pathogens threaten, an antimicrobial peptide known as cathelicidin is expressed if a person has a healthy immune system. The peptide is secreted by bladder epithelial cells and protects the urinary tract from an infection.
So what role does vitamin D play? The Swedish study found that vitamin D actually induces cathelicidin in the urinary bladder — but only when a boost in the antimcrobial peptide is needed in the face of a threatening infection. The researchers found this out when they analyzed bladder tissue biopsied from postmenopausal women to check for expression of cathelicidin before and after the research volunteers took supplements of vitamin D (in the form of 25-hydroxyvitamin D3) for three months. When the bladder cells were infected with the UTI-causing germ E. coli, the scientists observed a significant increase in cathelicidin expression after vitamin D supplementation.
This means vitamin D has a huge advantage over mainstream medicine’s widely prescribed antibiotics for urinary tract infections. That’s because when UTIs are treated with antibiotics, the drugs can harm beneficial bacteria in the gut and wreak havoc in the body. But vitamin D only produces germ-killing peptides at the site of an infection when needed, leaving “friendly bacteria” totally unharmed.
“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 [friendly] microbes elsewhere in the body,” the scientists stated in their paper.