Ketogenic Diet May Protect Against Colon Tumors but Increase Small Bowel Tumor Risk in Mice
A high-fat, low-carbohydrate ketogenic diet may help some people lose weight and has been linked to protection against colon cancer. However, new research suggests the same diet could increase the risk of tumors in the small intestine—at least in mice.
How the Ketogenic Diet Affects Intestinal Cells
During ketosis, the body burns fatty acids for energy instead of carbohydrates. This process produces byproducts called ketone bodies, including beta-hydroxybutyrate, or BHB. BHB was previously thought to help explain the diet’s potential protective effects against colon cancer.
Omar Yilmaz, director of the MIT Stem Cell Initiative, worked with MIT postdoctoral fellows Jessica Hsieh and Fangtao Qi and other colleagues to investigate whether the diet has similar effects in the small intestine.
Instead, the researchers found that mice fed a ketogenic diet were more likely to develop tumors in the small intestine than mice fed a control diet.
Why Small Intestinal Tumors Increased
Additional research indicated that the tumor growth was driven by the way intestinal cells use dietary fat for energy. This metabolic pathway, known as fatty acid oxidation, activates proteins that signal intestinal stem cells to multiply more quickly.
“More stem cells mean the small intestine is better able to repair itself when it is damaged, but the downside is that more active stem cells can lead to tumor formation,” Yilmaz says.
Ketone Bodies May Not Be Responsible
The researchers also confirmed that a ketogenic diet suppressed the development of colon tumors in mice. However, their findings suggested that ketone bodies were not responsible for this effect.
“These molecules are essentially metabolic bystanders,” Yilmaz says.
What the Findings Could Mean
The results suggest that over-the-counter ketone supplements may do little to help or harm people who take them. However, the study raises a broader question: Why might the same diet have opposite effects in two adjacent parts of the intestine?
“That’s what we’re working to understand next,” Chee says.
The findings also highlight the need for caution when generalizing about the health effects of ketogenic diets.
“The message here is that we need to be very careful in generalizing about the possible effects of these diets,” Yilmaz says.
Source: www.technologyreview.com