The ketogenic diet (KD) is a diet that reduces the carbohydrate intake and replaces it with fat. Although many people have been using it to lose weight, the KD has been used for other useful health effects, such as relieving seizures for patients with epilepsy. In a new study conducted by scientists in the University of California, San Francisco, the KD is shown to specifically alter the gut microbiome in a way that can reduce intestinal inflammation.
In the published study, 17 patients were fed a regular diet for 4 weeks followed by a KD for 4 weeks. The patients’ gut microbiome was compared before and after a KD, revealing that the amount of a common gut bacteria family, Bifidobacteria, consistently decreased after a KD. They repeated the study in mice and were able to reproduce this result. In mice, they were able to do further experiments to show that a KD reduces the level of pro-inflammatory immune cells in the gut, known as Th17 cells, suggesting that a KD may potentially reduce intestinal inflammation.
Interestingly, a high-fat diet containing similar high levels of fat intake as a KD did not produce the same outcome. So what is the difference between a high-fat diet and a KD? Unlike a regular high-fat diet, a KD does not contain any carbohydrates. Thus, a KD forces the body to metabolize fats, creating compounds known as ketone bodies, which are alternative energy sources that the body can use in place of glucose. When the scientists fed mice with ketone bodies, they were also able to see a similar reduction in Bifidobacteria in the gut microbiome as well as the amount of Th17 cells in the gut. This shows that the effects produced by a KD may in part be caused by the production of ketone bodies. The exact mechanism by which these ketone bodies alter the gut microbiome and the immune cells is still a mystery and still needs to be uncovered.
This study provides initial evidence that a KD and ketone bodies could be used to reduce inflammation in the gut, which would be beneficial for patients with inflammatory bowel diseases such as colitis and Crohn’s disease. Additionally, since the KD is a very strict diet and is difficult to follow, exploration of how ketone bodies could be used in place of a KD would allow many KD-based therapy to become more attractive.
Managing Correspondent: Wei Li
Press Article: Ketogenic Diet Alters Gut Microbiome Leading to Reduced Levels of Proinflammatory T Cells. Genetic Engineering & Biotechnology News.
Original Scientific Article: Ketogenic Diets Alter the Gut Microbiome Resulting in Decreased Intestinal Th17 Cells. Cell.