Importance of our Microbiome

The human body hosts a vast number of nonhuman microbes, which outnumber our own cells. These microbes, collectively known as the human microbiome, play crucial roles in our health and physiology.

Key Facts About the Microbiome

1. Microbial Ratio:

• For every human cell in the body, there are approximately 1.3 microbial cells, although estimates vary depending on the individual.

• These microbes include bacteria, viruses, fungi, and archaea.

2. Where They Live:

• The majority are found in the gut, particularly the large intestine.

• Others inhabit the skin, mouth, nasal passages, and urogenital tract.

3. Diversity:

• The human gut alone contains trillions of bacteria, representing hundreds of species.

• Key genera include Bacteroides, Firmicutes, and Actinobacteria.

Functions of the Microbiome

1. Digestion and Metabolism:

• Microbes help break down dietary fibers and produce short-chain fatty acids (e.g., butyrate) that nourish the gut lining.

• They assist in the synthesis of vitamins like B12 and K.

2. Immune System Support:

• Microbes train the immune system to distinguish between harmful pathogens and harmless antigens.

• They influence inflammation and autoimmune responses.

3. Protection Against Pathogens:

• The microbiome competes with harmful microbes for resources and space, reducing the risk of infections.

4. Brain-Gut Axis:

• Gut microbes produce neurotransmitters like serotonin, influencing mood, cognition, and behavior.

Human vs. Microbial Genome

• While human cells have about 20,000 genes, the combined genetic material of our microbiome (the “microbiome genome”) is estimated to contain over 2 million genes. This vastly expands the metabolic and functional capabilities of the body.

Implications for Health

• Disruptions in the microbiome (dysbiosis) have been linked to conditions like obesity, diabetes, depression, irritable bowel syndrome (IBS), and autoimmune diseases.

• Maintaining a healthy microbiome involves a diet rich in prebiotics (fiber) and probiotics (fermented foods), as well as avoiding unnecessary antibiotics.