The human microbiome and what we do to it

Summary

This transcript explores the human microbiome, highlighting that we are largely composed of microbial cells and genes. Professor David Relman explains the symbiotic relationship between humans and microbes, which aid in digestion, nutrient recycling, and protection against harmful pathogens. The overuse of antibiotics, however, can disrupt this balance, leading to severe impacts on microbial communities and potential health consequences. The discussion also touches on the potential benefits of probiotics in restoring a healthy microbiome, emphasizing the need for a new perspective on our microbial partners.

Takeaways

• 🌐 The human body is composed of a tiny percentage of human cells and a large percentage of microbial cells, suggesting a symbiotic relationship.
• 🧬 We are more microbial than human when considering the number of unique genes, with humans comprising only about 1% of our genetic makeup.
• 🌿 The human microbiome, a collection of microbial communities, has co-evolved with us and plays a crucial role in our health.
• 🛡️ Microbes provide functions that our bodies can't execute alone, such as the digestion of complex plant polysaccharides.
• 💪 Our microbiome acts as an internal shield, protecting us from harmful pathogens through a process known as competitive exclusion or colonization resistance.
• 📍 Microbes reside in all areas of our body that interface with the external environment, with particularly high concentrations in the colon.
• 🔄 The gut microbiome aids in the recirculation of valuable nutrients and helps maintain healthy cholesterol levels.
• ⚠️ Antibiotic use can have severe and long-lasting impacts on the microbiome, potentially leading to a decline in microbial diversity.
• 🤒 Antibiotics can lead to infections like Clostridium difficile, causing significant illness and death, especially in those who are already sick or weakened.
• 💊 Probiotics are suggested as a potential solution to restore friendly bacteria, although evidence of their effectiveness is still emerging.
• 🤔 There is a possibility that antibiotic overuse and the subsequent damage to the microbiome could be linked to chronic diseases like heart disease and cancer, but more research is needed.

Q & A

What is the human microbiome?

The human microbiome is a collection of microbial communities that have co-evolved with humans and are now considered part of the human landscape, providing essential functions that the human body cannot execute on its own.

How significant is the microbial component in comparison to human cells and genes?

It is estimated that we are ten parts microbial cells to one part human, and when considering unique genes, the difference is a factor of a hundred, meaning we are only one percent human in terms of unique genes.

What role do microbes play in our digestive system?

Microbes in our digestive system assist in the digestion of complex polysaccharides from plants, which humans are deficient in processing, and help in recirculating valuable nutrients and keeping cholesterol levels down.

How does the microbiome protect us from harmful invaders?

The microbiome provides an internal shield of friendly microbes that compete with and crowd out harmful pathogens, a process known as competitive exclusion or colonization resistance.

Where are the highest concentrations of microbes found in the human body?

The highest concentrations of microbes are found in the colon, with significantly lower numbers in the mouth, at ten million per gram compared to a hundred thousand times as many per gram in the colon.

What are the negative impacts of antibiotics on the microbiome?

Antibiotics can decimate microbial communities, leading to a severe impact on the microbiome, which is more pronounced in people who are already sick and weakened.

How does the microbiome recover after antibiotic use in healthy individuals?

In healthy individuals, the microbiome tends to recover quite well after an occasional course of antibiotics, although the recovery process can be slower and less complete in those who are sick or weakened.

What is Clostridium difficile and why is it a concern?

Clostridium difficile is a germ that can cause severe infections, particularly in people who have been treated with antibiotics, leading to hundreds of thousands of deaths worldwide.

What is the current understanding of probiotics in relation to the microbiome?

The evidence on probiotics is still early, but it suggests there may be potential benefits in replenishing friendly bacteria in the microbiome after antibiotic use.

Is there a known link between microbiome damage and chronic diseases like heart disease and cancer?

The link between microbiome damage due to antibiotic overuse and chronic diseases such as heart disease and cancer is not yet established, as no specific studies have been conducted to explore this connection.

What is the new perspective on bacteria and their relationship with humans?

The new perspective emphasizes the importance of bacteria as a significant part of our being, with 99% of what we are being non-human, and calls for a shift from viewing bacteria solely as enemies to recognizing their essential role in human health.