A new study shown below from the University of Michigan, Explored the gut microbes ability to produce short-chain fatty acids by testing different fermentable fibers.
They tested resistant starch from potatoes, corn, and chicory root and found all fermentable fibers increased short-chain fatty acids and potato starch led to the greatest increase.
Fusobacterium is a type of bacteria found in abundance in colorectal cancer. There many studies that suggest it’s the actual cause of colorectal cancer.
The bacteria that competes with Fusobacterium is Lachnospiraceae. Lachnospiraceae is protective of colorectal cancer and it competes with Fusobacterium. If one is high, the other is low and you want to feed good, protective, bacteria so it can kill pathogenic bacteria.
How to feed Lachnospiraceae (the good bacteria)? It feeds off fiber and short-chain fatty acids like butyrate. Butyrate itself has substantial anti-cancer properties and for the test subjects in the group, their supplementation with resistant potato starch correlated positively with higher fecal butyrate concentrations.!
So in a nutshell, without carbs and fiber the protective bacteria in the gut die off leaving the pathogenic bacteria to take over.