Bacteria in the gut may affect the chance of developing bowel cancer, according to studies in the latest study linking human health to the germs inside.
The gut microbiome – the collection of fungi, bacteria and viruses in our gut – is a thriving research topic, with scientists suggesting that some microbial makeup may be associated with conditions ranging from anxiety to obesity.
But learning about this collection of germs can also be helpful: there is increasing interest in using fecal transplants to treat some cases of Clostridium difficile .
"We are trying to do a lot with regard to cancer prevention. Despite the fact that the microbiome can play, much more is needed and interdisciplinary research is needed to try to help in this area, "said Dr. Kitelin Wade, a researcher at the University of Bristol, who presented the findings at the National Conference Glasgow Cancer Research Institute
The study – yet to be published or reviewed – includes Wade and colleagues, who looked at genetic microbiome and gut data from about 4,000 people in three European projects and examined whether or genetic variants associated with the presence of certain bacteria in the gut, since such genetic variants are spread randomly throughout the population, the approach is a kind of natural experiment.
The team found 13 genetic variants, each related to variations in They then looked at another dataset of about 2,000 people to see if those with genetic variants were more likely to develop bowel cancer.
The results reveal those whose genes increase the likelihood of having Bacteroidales bacteria are at a 2% to 15% increased risk of disease. The team said the findings support previous studies suggesting that bacteria are more common in those with bowel cancer.
But since genetic composition is determined early in life, the study suggests that these bacteria could play a role in actually causing gut cancer
Many questions remain, including whether the genetic variants associated with gut bacteria, directly lead to an increased risk of bowel cancer. "The actual genetic changes [themselves] can be related to the disease first and foremost, which then leads to bacterial variation," Wade says.
It may also be that these variants lead to a preference for a particular diet, which may directly influence the risk of bowel cancer or affect the composition of the microbiome, affecting the chance of developing the disease.
Wade said the team now has to determine the exact type of Bacteroidales that appears to be related to bowel cancer, and added that more research is needed to investigate whether changing the levels of these germs can reduce the risk of bowel cancer – and whether such an approach can have unintended consequences.
"What we need to do with regard to further work is to understand not only what the bacteria are [specific] [behind this link]," Wade said, "but also to understand what potential effects on the target it might have if we are interested in changing [these bacteria]. "
Prof. Tim Spector, an expert on gut microbiome at King's College London and author of The Diet Myth, said the study was a step in the right direction to unlock the link between gut cancer and the gut, but that there is a long way to go
"The problem is – like genes – there is no criminal and there are probably hundreds of germs that alter our risk of cancer [bowel]," he said. "At the moment our best protection is to cultivate the the healthiest variety of intestines by eating a wide variety of plants full of fiber and polyphenolic chemicals. "