A study conducted in British Columbia seeks to understand how night work may affect the health of the gut microbiome, which may lead to an increased risk of cancer in night workers.
We know at first glance that night shifts are associated with an increased risk of cancer among these workers, notes Canadian researcher Parveen Bhatti, who led the study. In Canada, 1.8 million people work a midnight-to-5 a.m. shift. Bhatti, of the British Columbia Cancer Research Institute and Cancer Control Research, says that night shifts can alter the composition and activity of the microbial communities that live in the gut. The gut microbiome, home to billions of bacteria, has its own daily cycle. Bacteria have a 24-hour cycle that affects their function and even their composition.
Night shift workers are a group of people who suffer from circadian rhythm disorder. “Because they don’t sleep when they should. Millions of years of evolution have ensured that our biology is wired to the day-night cycle. […] “That kind of disconnects them from what the body is programmed to do, including the microbiome,” Bhatti explained. “So night shifts kind of disrupt the gut microbiome. These people are eating at a time of day when the body is not programmed to receive food. The gut microbiome takes a part of the diet and transforms it to be able to perform different functions in the body.”
“The microbiome is not programmed to receive these nutrients at these times of day, leading to disruption and dysfunction that can have physiological consequences such as cancer,” he says. The negative impact of night shifts on the gut microbiome can lead to increased inflammation, which may contribute to the development of cancer. “More specifically, a healthy gut microbiome synthesizes short-chain fatty acids that are important for the body’s immune response. We understand that when there is an imbalance in the synthesis of these short-chain fatty acids, you can have increased inflammation. This may be one way that night shifts increase cancer risk,” the researcher says.
Identify differences
Bhatti can’t say for sure whether the microbiome can adapt to an unusual schedule, but he doesn’t think it can. The researcher believes this kind of disruption can occur even in people who always have the same night schedule, since on weekends they risk synchronizing with a more daytime schedule. In their research, Bhatti and his team want to determine the differences between the gut microbiomes of night and day workers and see how that affects cancer risk. They will begin recruiting participants for the study soon. The goal is to compare a group of 200 night workers from British Columbia with a group of 100 day workers. The research will allow us to see, among other things, whether there are fewer types of bacteria involved in the synthesis of short-chain fatty acids in the gut microbiome of night workers.
Mr. Bhatti’s research will span two years. To make it happen, the project has received funding of around $200,000 from the Canadian Cancer Society and the Canadian Institutes of Health Research. In the future, Bhatti hopes to have a second phase of his research where he will be able to see if a specific type of gut microbiome dysfunction in night shift workers is linked to an increased risk of cancer. “This type of research is more complex because you have to follow people over a long period of time. It could take decades before they develop cancer,” he says. Mr. Bhatti stresses that night work is not going away, as it is now an integral part of our societies. “We really need to develop interventions to reduce the risk of chronic diseases, especially cancer, in this group,” he says. The goal of the study is to provide insights into reducing the risk of cancer associated with night shift workers, for example by changing diet or intervening with sleep.
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Caption and photo: A British Columbia study seeks to understand how night shift work can affect gut microbiome health. Paramedics attend the scene of a shooting in Etobicoke, northwest of Toronto, Saturday, June 19, 2021. The Canadian Press/Chris Young
