High fat diet 'increases risk of bowel cancer'


Over the past decade, studies have found that eating a high-fat, high-calorie diet poses a serious risk in the formation of many types of cancer. Now, a new study conducted by America's Massachusetts Institute of Technology (MIT) has found that a high-fat diet makes the cells of the intestinal lining more likely to become cancerous.

According to researchers, such a diet generates a pool of other cells that behave like stem cells which can then reproduce themselves indefinitely.

Bowel cancer is one of the most common types of cancer diagnosed in the UK, with around 40,000 new cases every year. About one in every 20 people in the UK will develop bowel cancer in their lifetime.

Team leader Assistant Professor Omer Yilmaz explained that to investigate a possible link between these stem cells and obesity-linked cancer, researchers fed healthy mice a diet made up of 60 per cent fat for nine to 12 months.

This diet is much higher in fat than the one typical in America, which is usually about 20 to 40 per cent fat.

During this period, the mice on the high-fat diet gained 30 to 50 per cent more body mass than mice fed a normal diet, and they developed more intestinal tumours too.

These mice also showed some distinctive changes in their intestinal stem cells, the researchers discovered.

First, they found that the rodents on a high-fat diet had many more intestinal stem cells than mice on a normal diet. These stem cells were also able to operate without input from neighbouring cells.

Normally, intestinal stem cells are surrounded by support or “niche” cells, which regulate stem cell activity and tell them when to generate stem cells or differentiated cells.

However, the stem cells from mice on a high-fat diet were more able to function on their own; when they were removed from the mice and grown in a culture dish without their niche cells, they gave rise to “mini-intestines” much more readily than intestinal stem cells from mice on a normal diet.

Professor Yilmaz's lab is now further investigating how this happens in hopes of identifying possible cancer drug targets for tumours that arise through obesity.

“Not only does the high-fat diet change the biology of stem cells, it also changes the biology of non-stem-cell populations, which collectively leads to an increase in tumour formation,” he said.

Researchers added that the study convincingly offers a potential explanation for the mechanism by which a high-fat diet contributes to cancer.

The study was first published in journal Nature.

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