The impact of the microbiome on food digestion: what happens in the gut

The microorganisms that live inside us may seem like outsiders, but without them, digestion would be incomplete. The gut microbiome is not just a collection of bacteria, but an active system that interacts with enzymes, the epithelium, and even the brain. In this article, we will consider the role of the microbiome precisely from the perspective of digestive mechanisms, which it provides.

The main stages of microbiome participation in digestion

1. Help with fiber breakdown

In the small intestine, digestion of dietary fiber almost does not occur, because humans lack the enzymes for this process. The colonic microbiome, in particular bacteria of the genera Bacteroides і Firmicutes. They break down cellulose, hemicellulose, and pectins to form short-chain fatty acids (SCFAs), which provide energy for intestinal cells.

2. Synthesis of nutrients and metabolites

Some of the vitamins and compounds that the body uses are formed precisely as a result of microbial activity. These include:

• Vitamin K

• Biotin (B7)

• B vitamins

• Folic acid

3. Regulation of acidity and enzymes

Microbiome affects the acid-base balance in the intestine. Some bacteria change the pH level, creating optimal conditions for the action of intestinal enzymes, such as amylase or lipase.

Why digestion is disrupted without a microbiome

In dysbiosis, when the balance of microorganisms is disrupted (for example, due to antibiotics or a low-fiber diet), a number of negative changes occur:

• The formation of CFA decreases → the epithelium is poorly nourished → inflammation of the intestinal wall

• The absorption of trace elements (iron, magnesium, calcium) deteriorates.

• Increased permeability of the intestinal barrier (leaky gut syndrome)

• Conditionally pathogenic bacteria may become active

All this disrupts not only digestion, but also the body's overall metabolism, affecting immunity and mood.

Example from the study

According to the publication Nature Microbiology (2023), in a group of people with IBS (irritable bowel syndrome), a decrease in the level of Faecalibacterium prausnitzii — one of the key producers of butyrate. The control group with high levels of this species had better peristalsis and fewer symptoms of flatulence.

What modern science recommends

International medical institutions, in particular WHO і Harvard School of Public Health, call for a personalized approach: microbiome research (metagenomics) helps select nutrition and even probiotics for individual needs.

Infographics

Building and maintaining a healthy microbiome is not a temporary solution, but a long-term strategy. A diet rich in fiber (fruits, vegetables, grains), regular physical activity, and moderate use of antibiotics are key to maintaining a balanced microflora and efficient digestion.