Metabolites: our research into how obesity can cause cancer

Study of human organs from model in Lab

We know that people who live with overweight or obesity have a higher risk of cancer. So why are we funding more research into the links?

World Cancer Research Fund are funding researchers from Bristol University to investigate the links between obesity and bowel cancer. Emma Vincent and Caroline Bull, are two of the scientists involved in the project, they explain why research in this field is so necessary and how obesity increases cancer risk.

We know that obesity can increase the risk of at least 12 types of cancer, but we don’t know exactly how it causes cancer. To understand this, we need to investigate the mechanisms involved – how what we eat affects the molecules and cells in our body, and how this can affect our risk of developing cancer.

What’s the link between obesity and cancer risk?

There are many ways in which obesity could increase cancer risk. Some suggested links include increased inflammation and altered levels of growth factors or hormones, which may all act to encourage cancer growth.

Obesity and the diseases it’s linked to, including cancer, is an increasing problem. People living with obesity are also living longer, mainly due to improvements in preventing or treating cardiovascular disease. This means that the rate of cancers caused by obesity is set to rise.

Previous research has shown that it is very difficult to reduce the rate of obesity in a population. As obesity itself cannot be sustainably reduced, another way to reduce cancer risk is to avoid the cause and target the mechanisms linking obesity with cancer. Understanding these mechanisms is important for the development of prevention and treatment strategies so that we can reduce the rate of cancer diagnoses and so that those who are diagnosed are more likely to survive.

Obesity and bowel cancer

World Cancer Research Fund’s report shows strong evidence that living with overweight or obesity increases bowel cancer risk. Motivated by this evidence, our group at Bristol University is conducting interdisciplinary research (research that involves two or more academic disciplines) to uncover the mechanisms linking obesity with bowel cancer. We have chosen this method because when results from differing approaches point towards the same conclusion this strengthens confidence in the findings – a practice known as  triangulation.

Our research on metabolites

We’re investigating whether changes to the levels of metabolites in the blood of people living with obesity are responsible for the increased risk of bowel cancer. You may not have heard of metabolites but another word – metabolism – may be more familiar to you. Metabolism is a process in which the body breaks down food, drugs, chemicals or its own tissue. This process makes energy and the materials needed for growth, reproduction and maintaining health, and removing toxins, and all these processes involve small molecules called metabolites.

Obesity causes widespread changes in circulating metabolite levels and our group has published a paper demonstrating this. This means that the cells and tissues of people living with obesity are exposed to a different metabolic environment. We are investigating whether this altered metabolic environment links obesity with bowel cancer.

We’ve examined more than 100 metabolites and have found some interesting associations, but no convincing links which could explain the relationship between obesity and bowel cancer. So we’re now broadening our approach using new techniques to uncover whether other metabolites are the link.

Why is more research necessary?

If we can identify metabolites that link obesity with bowel cancer, we hope it will be possible to develop drugs to target these metabolites to prevent or treat bowel cancer. This knowledge could also be used to develop models to better predict the risk of bowel cancer in people living with obesity.