1.2 Balancing the gut microbiome

The balance between the different bacterial groups within an individual’s enterotype is important in maintaining health, as is the balance between pathogenic and symbiotic bacteria of the microbiome. In fact, some microorganisms within the microbiota actually help to maintain this balance between pathogens and beneficial/harmless microbiota (working alongside the immune system) to avoid the development of disease.

In Figure 4, you saw that there is a different distribution of bacteria contained within the different microbiomes around the body. While this figure shows the typical distribution of bacteria, every human actually has a unique combination of microorganisms that form their microbiota. This can be seen in Figure 5, which shows the bacterial groups of the gut microbiota from five individuals.

Figure 5 Bar chart (presented horizontally) showing the proportions of the different bacterial groups making up the microbiota within the gut of five individuals

Show description|Hide description

A horizontal stacked bar graph depicts the proportions of different bacteria making up the microbiota within the gut of 5 individuals. The horizontal axis is labelled proportions of the microbiome bacteria in human gut in per cent and ranges from 0 to 100 in increments of 10 units. The vertical axis is labelled individuals and ranges from 1 to 5 in increments of 1 unit. The data for 5 individuals is represented as follows: Individual 1 has approximately 2.7 per cent of Actinobacteria, 2.3 per cent of Bacteroidetes, 90 per cent of Firmicutes, 0.2 per cent of Fusobacteria, 2.6 per cent of Parcubacteria, and 2.2 per cent of Proteobacteria. Individual 2 has approximately 0.2 per cent of Acidobacteria, 84.3 per cent of Actinobacteria, 2.4 per cent of Bacteroidetes, 7.4 per cent of Firmicutes, 0.2 per cent of Parcubacteria, 5.4 per cent of Proteobacteria, and 0.1 per cent of Tenericutes. Individual 3 has approximately 25 per cent of Actinobacteria, 73 per cent of Firmicutes, and 2 per cent of proteobacteria. Individual 4 has approximately 35 per cent of Actinobacteria, 31 per cent of Firmicutes, 0.1 per cent of Fusobacteria, 10 per cent of Proteobacteria, and 23 per cent of Tenericutes. Individual 5 has approximately 37.8 per cent of Actinobacteria, 0.1 per cent of Fusobacteria, 50.5 per cent of Firmicutes, 11.5 per cent of Proteobacteria, and 0.1 per cent of Tenericutes.

Figure 5 Bar chart (presented horizontally) showing the proportions of the different bacterial groups making up the microbiota within the...

There are many factors which contribute to the microbiota profile of an individual. These include:

• genetic make-up
• exposure to microorganisms during pregnancy and early postnatal development
• geographical exposure to different environments
• diet
• exercise
• antibiotics, antimicrobials and other medications
• infection and disease
• age, including menopause.

Some factors, such as medications, menopause and disease, reduce the diversity of the organisms in the gut microbiota. Certain foods can also disrupt the normal balance of the bacterial species within the microbiota, while some other foods, pre/probiotics and exercise can improve the health of the microbiota, by promoting the growth of beneficial bacteria. All of these factors can have an impact on the health of the individual, and in the next section you are going to start to learn more about an unbalanced microbiome.