High-Fat Diet May Raise Cancer Risk
Over the last 10 years studies have shown that being obese and eating a high-fat, high-calorie diet can raise the risk of many types of cancer. Now a new study published in Nature may have discovered the mechanism by which that happens.
Research on mice suggests that by boosting stem cell production in the gut -- and also by inducing other cells to mimic stem cells -- a high-fat diet could increase the risk of colon cancer.
The study team fed healthy mice a diet of 60% fat for 9 months (a much higher proportion of fat than the 20-40% fat content of the average American diet). The mice gained 30-50% more body mass and developed more intestinal tumors, compared with healthy mice on a normal diet.
When they examined the mice's gut tissue, researchers found the ones fed a high-fat diet had many more intestinal stem cells than the mice on a normal diet. More significantly, the team noticed that the boosted population of stem cells had a very distinctive feature -- they could operate independently of the cells around them.
Under normal circumstances, stem cells interact with support or "niche" cells that surround them. These niche cells regulate stem cell activity and signal to them when it is time to differentiate into tissue-specific cells.
But the stem cells from the intestines of mice on the high-fat diet were so independent of their niche cells that, when cultured outside the body, they could produce "mini-intestines" much more readily than stem cells from normal-fed mice.
These findings are important because scientists already know that intestinal stem cells are often the cells of the gut that develop and accumulate mutations that give rise to cancer.