Researchers are continuing to find links between vitamin D levels and critical processes throughout the body, including, several studies indicate, intestinal health.
This inexpensive vitamin, actually considered a hormone, may alleviate Crohn’s symptoms in some patients. In addition, because there is a genetic component to the illness, taken prophylactically, vitamin D may prevent Crohn’s' siblings and offspring from manifesting the disease.
Vitamin D and Crohn’s Disease
Crohn’s is a chronic condition characterized by inflammation and ulcers (open sores) along the innermost layer of the digestive tract. Crohn’s can appear along the entire gastrointestinal tract (from the mouth to anus), although the majority of cases involve the small intestine or the first part of the large intestine. The cause of the disease is largely unknown; although genetic and environmental factors may play a role.
Vitamin D, in its active form (1,25-dihydroxyvitamin D), is a hormone that binds to receptors in the body's cells. Despite the name, vitamin D is actually a secosteroid hormone that targets over 2000 genes. Vitamin D has been shown to have a positive effect on bone health, immunity, cancer prevention and inflammation. Taken orally, vitamin D is absorbed with fat through the intestinal walls and is stored in the fat cells of the liver, skin, brain and bones in amounts sufficient for many months.
While not readily available in foods, vitamin D is made in large quantities when sunlight strikes bare skin, which is why a deficiency is more common in the winter. A number of other factors contribute to low D, including malabsorption, common in people with an inflammatory bowel disease. The production of vitamin D in the body is blocked by anything which blocks ultra violet light including skin pigment, smog, fog, sunscreen, windows and hats.
Studies Link Vitamin D Deficiency to Crohn’s and Inflammatory Bowel Diseases
Researchers in a 2009 study report that, "Western studies indicated that up to 65 per cent of patients with Crohn’s disease have low serum 25-hydroxy vitamin D concentrations, and 45 per cent of these patients have metabolic bone disease." The scientists found vitamin D levels significantly lower among patients with Crohn’s disease as compared to age and sex matched controls. Further, D levels in patients with Crohn’s disease were lower in those with severe disease activity and less sun exposure.
Most recently in a 2010 study, Dr. John White and his team found evidence to suggest that sufficient vitamin D may counter the effects of Crohn’s disease.
White was initially studying the effects of D on cancer; however, results consistently pointed to D's effect on the immune system, specifically the innate immune system that acts as the body's first defense against microbial invaders. As a result, Dr. White began investigating the potential link to Crohn’s. "It's a defect in innate immune handling of intestinal bacteria that leads to an inflammatory response that may lead to an autoimmune condition," White explains.
Several studies showed a link between vitamin D and inflammatory bowel diseases, including a 2006 finding out of Ireland where researchers found a high proportion of Crohn’s patients had some level of vitamin D deficiency during late-wintertime. The researchers suggest use of regular low-dose supplemental vitamin D, particularly by patients with small intestinal involvement, cessation of smoking, adequate, but responsible, exposure to summer sunlight as well as maintaining a body mass index in the normal range may help maintain adequate vitamin D levels during wintertime.
Vitamin D and Innate Immunity
Vitamin D's role in intestinal health involves the beta defensin 2 gene, a gene coding for an important defense molecule of the body. Defensins are part of the arsenal of weapons used by the human immune system. Patients with Crohn’s disease of the colon (colonic CD) have a lower level of beta-defensins in the mucous membranes.
Beta defensin encodes an antimicrobial peptide and the NOD2 gene that alerts cells to the presence of invading microbes. If NOD2 is deficient or defective, it can't attack invaders in the intestinal tract.
An international research team with the Robert Bosch Hospital in Stuttgart and the German Cancer Research Center in Heidelberg discovered a possible cause of the chronic inflammations. They believe Crohn’s patients have one copy less of of this protective beta-defensin 2 gene.
Scientists found that a lower number of gene copies are associated with reduced production of the endogenous antibiotic, which explains the known low defensin level. They believe this causes the protective intestinal mucous membrane to become so porous that bacteria can attach to and invade the mucous membrane, which leads to the typical inflammatory hot spots of Crohn’s disease.
Implications for Vitamin D and Inflammatory Diseases
The impact of such findings have important implications for Crohn's patients, explains Dr. White. "Siblings of patients with Crohn’s disease that haven't yet developed the disease might be well advised to make sure they're vitamin D sufficient. It's something that's easy to do, because they can simply go to a pharmacy, health food store, or online and buy vitamin D supplements. The vast majority of people would be candidates for vitamin D treatment."
"This discovery is exciting, since it shows how an over-the-counter supplement such as vitamin D could help people defend themselves against Crohn’s disease," says Marc J. Servant, a professor at the Université de Montréal's Faculty of Pharmacy and study collaborator.
Although researchers now believe most people are likely low in D, patients with Crohn's disease or other inflammatory bowel disease may be particularly vulnerable to a deficiency.
Sources:
White, JH et al., "Direct and indirect induction by 1,25-dihydroxyvitamin D3 of theNOD2/CARD15-beta defensin 2 innate immune pathway defective in Crohn’s disease," The Journal of Biological Chemistry, January, 2010.
Gilman J, Shanahan F, Cashman KD, "Determinants of vitamin D status in adult Crohn’s disease patients, with particular emphasis on supplemental vitamin D use," European Journal of Clinical Nutrition," 2006 Jul.
"Crohn’s Disease: One Gene Copy Too Few Leads To Weakened Defense," Medical News Today. Accessed April 15, 2010. http://www.medicalnewstoday.com/articles/47508.php
Vitamin D Council, "Inflammatory Bowel Disease" Article Links. Accessed April 15, 2010.
Laura Owens - Laura Owens has a B.S. in Psychology from Rollins College & U of FL. She is a freelance writer with expertise in motivation & wellness.
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