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Gut Fermentation: The Key to a Healthy Microbiome

When most people hear the word ‘fermentation’ in relation to the gut, they think of fermented foods. While fermented foods can be beneficial for a healthy gut, and will be covered in this blog, we are first going to discuss the natural fermentation process that happens in the gut and why it’s important.

What is fermentation in the gut?

Fermentation is defined as the breakdown of substances in the absence of oxygen and occurs in the colon, an oxygen-free environment where most of the gut bugs reside.

The substances fermented are compounds of the food you consume that are not digested in the small intestine, which happens simply because the body has no mechanism to break them down, or in the case of poor digestion or excess consumption. These substances are predominantly dietary fiber and protein, but also include other compounds such as fat and polyphenols.

Once they reach the colon, these substances are exposed to gut microbes. Some of these microbes are capable of breaking down these compounds, releasing energy and nutrients. This drives their metabolic activity and fuels their growth, supporting the overall microbial population and producing a range of by-products for our body or other microbes to use.

The type of by-product produced depends on the type of substance fermented. These by-products can be either:

  • Beneficial, such as short-chain fatty acids (SCFAs), vitamins (mainly vitamin K and B vitamins);

  • Benign or generally harmless, such as gases (carbon dioxide, hydrogen, hydrogen sulphide and methane); or

  • Potentially harmful, such as ammonia and phenols.

What are the benefits of fermentation?

Fermentation of carbohydrates and carbohydrate-based substances (such as fiber) leads to production of beneficial by-product, like vitamins and SCFAs, as well as providing fuel and promoting the overall abundance and diversity of the gut microbes that make up the gut microbiota.