IB Sports, exercise and health science A.2.2.5 Influence of the Gut Microbiome on Health and Performance Notes

The Influence of Gut Microbiome on Health and Performance

1. The gut microbiome refers to the diverse community of microorganisms, including bacteria, viruses, fungi, archaea, and protozoa, that reside in the gastrointestinal (GI) tract, predominantly in the large intestine (colon).
2. These microorganisms play a critical role in digestion, metabolism, immune function, brain health, and overall physiological performance.

Microbial Density Along the Gut

1. Stomach, duodenum, jejunum: Low microbial density (acidic and motile environment).
2. Ileum and colon: Density rises dramatically; the large intestine houses most of the gut microbiota.
3. Gene count: The microbiome contains about 3 million genes, compared to ~23,000 in the human genome.
4. Personal uniqueness: Each person's microbiome is as unique as a fingerprint, shaped by genes, diet, environment, and history.

Microbiota vs Microbiome

1. Microbiota: The microorganisms themselves (bacteria, viruses, fungi, archaea, protozoa) living in a specific environment such as the gut, skin, or mouth.
2. Microbiome: The collection of genomes of all those microorganisms, plus their surrounding environment.

Why is the Gut Microbiome Important?

1. The gut microbiome is not a passive system; it actively interacts with the body in several ways:

1. Helps break down complex carbohydrates, fiber, and proteins into short-chain fatty acids (SCFAs) for energy.
2. Synthesizes essential vitamins (B vitamins, vitamin K) required for metabolism and blood clotting.
3. Supports immune function by helping to identify harmful pathogens.
4. Regulates metabolism, influencing body weight, fat storage, and insulin sensitivity.
5. Impacts mental health via the gut-brain axis, influencing mood, cognition, and stress response.
6. Affects athletic performance by influencing energy levels, inflammation, and muscle recovery.

How the Gut Microbiome Influences Health and Performance

Digestion & Nutrient Absorption

1. Certain gut bacteria break down dietary fiber into short-chain fatty acids (SCFAs), which provide energy for colon cells and reduce inflammation.
2. Bacteria assist in synthesizing vitamins B and K, necessary for metabolism and blood clotting.
3. Gut microbes help digest proteins and fats, improving energy availability.

Immune System Regulation

1. About 70% of the body's antibody-producing immune cells are located in the gut.
2. Beneficial microbes help train immune cells to recognize harmful pathogens while preventing autoimmune overreactions.
3. Dysbiosis (microbial imbalance) can increase inflammation, leading to allergies, autoimmune diseases, and infections.

Intestinal Permeability and Athlete Illness

1. Undesirable microbiota: Associated with increased intestinal permeability, letting bacteria leak from the gut into the bloodstream.
2. Immune response trigger: The leaked bacteria trigger systemic immune reactions, raising the risk of upper respiratory tract infections (URTIs).
3. Energy availability link: Athletes with chronic low energy availability tend to show reduced gut microbial diversity, contributing to decreased immune function and reduced nutrient absorption.

Metabolism and Energy Regulation