Previous research has suggested that a diet rich in fiber may reduce the risk of colon inflammation and cancer. But new research suggests that niacin, also known as vitamin B3, may also help protect against these conditions.
The research team, including co-author Dr. Vadivel Ganapathy of the Medical College of Georgia at Georgia Regents University, says their findings help explain why a diet high in fiber can reduce the risk of colon-related health conditions and suggests that niacin - supplements already used to regulate cholesterol - can keep the colon healthy for people who have low-fiber diets.
To reach their findings, recently published in the journal Immunity, the investigators conducted a mouse study.
But on giving niacin to mice who had no healthy colonic bacteria - because it had been destroyed by antibiotics - the researchers found the vitamin pushed immune cells into an anti-inflammatory mode.
Immune cell receptor activated by fiber digestion
To explain the mechanisms of the study findings, co-author Dr. Nagendra Singh, of the Cancer Center at Georgia Regents University, begins by noting that good bacteria in the colon flourish on fiber.
The digestion of fiber leads to the production of butyrate - a short-chain fatty acid. Previous research by Dr. Singh revealed that butyrate activates the Gpr109a receptor.
But he says that this only seems to happen in the colon and that a high-fiber diet significantly increases butyrate levels in this area.
Butyrate triggers the Gpr109a receptor in immune cells - macrophages and dendritic cells - in the colon.
Dr. Singh explains that these immune cells produce anti-inflammatory molecules and transmit signals to T cells - white blood cells that play a major role in the immune system - which also causes the T cells to produce anti-inflammatory molecules.
Additionally, epithelial cells that line the colon are triggered by butyrate to produce cykotines - soluble proteins that help wound healing.
Dr. Singh notes that this process is crucial when in comes to healing intestinal inflammation that is found in medical conditions such as Crohn's disease and ulcerative colitis.
Niacin has colon-protecting properties
Dr. Ganapathy says that in order for a person's colon to be protected, they need to have the Gpr109a receptor alongside a high intake of fiber to produce butyrate, which activates the receptor.
But Dr. Singh notes that their findings suggest high doses of niacin may have a similar effect, which is good news for individuals who have a diet low in fiber.
"We think mega-doses 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."
The researchers say they are looking to carry out clinical trials to determine whether niacin supplements may help reduce the risk of intestinal inflammation and colon cancer in patients already using them for cardiovascular health.