AUGUSTA, GA — A receptor already activated with megadoses of niacin to protect the cardiovascular system also might play a key role in preventing colon inflammation and cancer, according to a new study including researchers from the Charlie Norwood VAMC in Augusta, GA.
The National Institutes of Health-funded study, recently featured on the cover of the journal Immunity, helps explain why a high-fiber diet reduces the risk of colon issues and that niacin, or vitamin B3, can help mitigate those, said co-author Vadivel Ganapathy, PhD, chairman of the Department of Biochemistry and Molecular Biology at the Medical College of Georgia at Georgia Regents University, also in Augusta.1
Researchers found that mice lacking the receptor Gpr109a were prone to inflammation and cancer of the colon, added co-author Nagendra Singh, PhD.
When the mice whose healthy colonic bacteria had been wiped out by antibiotics were given niacin, however, the vitamin helped steer immune cells in the colon into an anti-inflammatory mode, according to the researchers.
Results indicate that activation of the receptor Gpr109a in the colon by butyrate, a short chain fatty acid derived from the microbial fermentation of dietary fibers in the colon, prompts immune cells to suppress rather than promote inflammation, a factor in Crohn’s disease and ulcerative colitis, as well as colorectal cancer.
Butyrate also prompts epithelial cells that line the colon to produce cytokines, which aid wound-healing, a critical step for resolving the intestinal inflammation that occurs in inflammatory bowel disease (IBD), according to Ganapathy.
“To protect your colon, you need this receptor, as well as the fiber and butyrate which activate it,” Ganapathy said.
“We think megadoses of niacin may be useful in the treatment and/or prevention of ulcerative colitis, Crohn’s disease, and colorectal cancer as well as familial adenomatous polyposis, or FAP, a genetic condition that causes polyps to develop throughout the gastrointestinal tract,” Singh added.
Previous research from the study authors has shown that fiber depletion increases and meganiacin doses decrease development of polyps in mice with FAP.
1 Singh N, Gurav A, Sivaprakasam S, Brady E, Padia R, Shi H, Thangaraju M, Prasad PD, Manicassamy S, Munn DH, Lee JR, Offermanns S, Ganapathy V. Activation of Gpr109a, receptor for niacin and the commensal metabolite butyrate, suppresses colonic inflammation and carcinogenesis. Immunity. 2014 Jan 16;40(1):128-39. doi: 10.1016/j.immuni.2013.12.007. Epub 2014 Jan 9. PubMed PMID: 24412617.