“That’s great news to hear,” Harbeson said.
It is further evidence of a remarkable balance for good health maintained between bacteria in the gut, diet, and the body, the GRU researchers said.
It has long been established that eating a diet high in fiber helps to protect against colon inflammation and cancer but exactly how that happens was not known, the GRU researchers said. Writing in a study in the journal Immunity, the researchers look at the relationship between the “good” bacteria in the colon fermenting fiber to create a chemical called butyrate.
“Because without fiber, this bacteria cannot make butyrate,” said Dr. Vadivel Ganapathy, a Regents’ Professor and chair of the Department of Biochemistry and Molecular Biology and co-author of the study. “And the fiber alone, without the good bacteria, cannot make the butyrate. So you need both.”
Two previous studies, one from Japan and one from Memorial Sloan-Kettering Cancer Center, noted the ability for butyrate to act on immune cells but did not identify the receptor, Ganapathy said. The GRU team found a receptor in the cells lining the colon called Gpr109a that appeared to react to the butyrate and lead to less inflammation. Also, mice bred to lack this receptor were more prone to colon inflammation and colon cancer, he said.
This was the first work in an animal model to prove that, Ganapathy said. But in addition to butyrate, the receptor appears to have another role and another name, said Dr. Nagendra Singh, a member of the Cancer Immunology, Inflammation and Tolerance Program at Georgia Regents University Cancer Center and lead author of the study.
“The receptor is also called Niacin Receptor 1 because it is newly discovered and still scientists haven’t come to a conclusion about how to name it,” he said. Working again in mice, the GRU team found niacin could calm inflammation by working through that receptor. That inflammation is important in the development of colon cancer, Singh said.
“We know that it is a lot more inflammation-driven than most of the other cancers,” he said.
Niacin, or vitamin B3, is found in many foods such as eggs, lean meats, dairy, nuts and legumes and is used to fortify breads and cereals, according to MedlinePlus Medical Encyclopedia. But the level in the diet is not sufficient to activate the receptor in the colon to get the beneficial effect, Ganapathy said. Millions of people are already taking a much higher dose, however, as a way to boost their HDL or “good cholesterol” levels and that dose might do the trick, Ganapathy said.
“It would be very nice to do that kind of epidemiological study to prove our point that it is possible that the people who are taking niacin as a drug to increase the good cholesterol may get another benefit that they do not know about and that is it might decrease the colitis, the colonic inflammation, and the colon cancer,” he said.
Based on what he found in his own work, Ganapathy said he has started taking 500 milligrams a day of niacin.
In another mouse model of a hereditary disease that causes polyps throughout the intestines, the niacin doses either stopped the growth or shrank the polyps and “it decreases even when the mice are not eating enough fiber,” Singh said. For Harbeson, 62, who has had a couple of polyps show up on colonoscopies in the past, that is more good news.
“That’s amazing,” he said.
Niacin supplementation then could be a way to aid people who already have the inflammation or lack fiber in their diet for some reason, Ganapathy said. The interplay of bacteria, diet and body brings up one of the more interesting paradoxes of the human body, where bacteria that would be attacked as foreign in the bloodstream are tolerated in the colon and play an integral part in its health, Ganapathy said.
“There are billions of bacteria in the colon. But our immune cells do not consider these bacteria as enemies,” he said. “
The puzzle is how is it our immune system does not see these bacteria as a foreign antigen but somehow they seem to work together in a friendly manner. Now it looks like the butyrate produced by this bacteria is the messenger to the host immune system to tell them, ‘We are not enemies. We are friends. So do not attack us.’ This is good for the normal symbiotic relationship.”
The problems come when that system is disrupted and researchers are still studying whether niacin could be the answer to help restore it in some cases, Singh said.
“Can we use it as a treatment? We don’t know yet,” he said. “But we are exploring it.”