Sucrose, Fructose and Microbiome

I am starting a series of knowledge-base threads backed by research to help answer some questions that keep coming up again and again. For a better understanding of the microbiome and its importance check out our guide on this.

The question here is:

do humans have gut bacteria for both sucrose (table sugar) and Fructose (fruit)? Is there sucrose gut bacteria that die off when you only eat fruit?

Fructose is what is called a monosaccharide. Monosaccharides, also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. Disaccharides are made up of two, linked monosaccharides and broken back down into the latter during digestion. Sucrose is a disaccharide consisting of one glucose and one fructose molecule, or 50% glucose and 50% fructose. So, as you can see there's an overlap in the population of gut microbiota that breaks down each sugar. Furthermore each type of sugar, when ingested in quantities has a different effect in the gut. A 2021 study points out that glucose can contribute to 'leaky gut syndrome' - a real bad news situation, but not fructose. Another study found that sucrose leads to alterations in the gut microbiome that turn good bacteria into bad ones. Finally fructose when ingested in high quantities can affect the liver.

So, really, the trick is to reduce sugar in the body as much as possible through smart dietary choices and a little attention to the sugar content of processed foods. I hope this helps.


Active member
Warrior Monk from London Ontario Canada
Posts: 37
"The Tao of Tai Chi Chuan"
Watch for maltodextrin said to be much the same as sugar but not listed under sugar on labels. We buy natural peanut butter and sometimes pick up a few things for a neighbour. She doesn't like plain just peanuts kind but the other supermarket kind. I notice the sugar is the same but the carbs much higher for hers coz of the maltodextrin.