Interesting point, I often wondered that too?
When all else fails we must really look at the science:
Currently what this information (below) tells me is that the gut flora microbiota requires different types of nutrition separate from the human host and if the human host is eating too much of it (carbohydrates), it spills over into the human host?
- “… not all of the starch you eat gets digested. …” “… This type of starch is called resistant starch, which functions kind of like soluble fiber. …” …More
- ”…excess simple carbohydrates are stored in the body as fat. …Other carbohydrates, such as the fiber found in whole grains, fruits, and vegetables, move slowly through the digestive system, and much of it isn’t digested at all (insoluble fiber). …” …More
- “…carbohydrates are not necessary building blocks for other molecules, and the body can obtain all its energy from protein and fat. Thus you could leave out carbohydrate from your diet provided you get enough protein, fat including essential fatty acids, vitamins, minerals and water. …More
- ”… Microbial fermentation of complex non-digestible dietary carbohydrates and host–derived glycans in the human intestine has important consequences for health. Certain dominant species, notably among the Bacteroidetes, are known to possess very large numbers of genes that encode carbohydrate active enzymes and can switch readily between different energy sources in the gut depending on availability. …” **…More
- “… Fructooligosaccharide (FOS), a prebiotic compound that can be digested by the microbiota but is indigestible by human enzymes due to the configuration of its glycosidic linkages …” …More