What is the human microbiome?

We humans are partly microbes. Over 100 trillion of them live on and inside our bodies. In fact, the number of microbes in an average human body is about the same as the number of human cells. Most of them can be found in our gut, particularly in the large intestine.
The microbiome is the genetic material of all these microbes and contributes to the broader genetic portrait, the metagenome, of a human. The composition of the human microbiome is unique in each individual. Different people harbour different collections of microbes – among which you encounter bacteria, archaea, fungi, protozoa and viruses – and we are only beginning to understand what leads to this variation.


Supporting the immune system

The gut microbiome has multiple ways to help and train your immune system to fight back harmful intruders.


Providing nutrients

Bacteria in the gut have the ability to break down indigestible food components into nutrients like vitamins or short-chain-fatty acids which are an important energy source for gut cells.


Preventing diseases

A diverse microbiome is assumed to have a lot of beneficial influences and might prevent different diseases.


How does the human microbiome relate to health?

The microbes living in and on us are generally not harmful, rather they are considered beneficial colonizers that are essential to maintain health. They help us break down our food to extract essential nutrients, produce certain vitamins and amino acids, regulate our immune system and fight off disease-causing microbes. Changes in the microbiome have been linked to numerous disease states such as obesity, diabetes, allergies and even anxiety, depression and autism. Most of these diseases are associated with imbalances in the gut microbiome, called dysbiosis, which have severe consequences for the host. This imbalance may result from an excess of harmful microbes and/or a lack of beneficial microbes to the host.


What is a “healthy” microbiome and what influences the composition of our microbiome?

Defining what a healthy microbiome is proves to be a very difficult task, simply because there are many things we don’t know yet. Even in healthy people, there are immense variations in the composition of the microbiome, making the concept of a healthy microbiome very challenging. However, there are certain things that we do know. For example, that there is a strong link between a high microbial diversity in the gut and overall health, while a relative lack of diversity is common in many diseases. If one thing is for certain, it is that the microbiome is subject to constant change. Although a person’s microbiome is originally determined by one’s DNA and the transmission of microbes from mother to infant in the birth canal, it changes with age, the effects of diet, medications, ethnicity, geography, and lifestyle. One important milestone of the Human Microbiome Action will be to establish a definition for the healthy microbiome.


How can we use microbiome knowledge to improve human health?

A more complete understanding of the diversity of microbes in the human microbiome could lead to new diagnostic tools, therapies and preventative strategies for numerous human diseases. For instance, imagine treating a bacterial infection caused by “bad” bacteria by growing more “good” bacteria!1 Ongoing research and joint effort in microbiome science will help improve human health as we become better at characterizing and manipulating the microbiome in a targeted way.2 It is also expected to shed light on fundamental aspects of human physiology and particularly human nutrition. A better understanding of the microbiome’s role in nutrition will produce changes in dietary recommendations, as well as in food production.


Therapeutic applications and areas of interest

Personalized medicine

With the advancement of sequencing technologies, analyzing an individual’s microbiome becomes easier and more affordable. Our knowledge about the interactions between the microbiome and drug metabolism and the microbiome’s role in disease development can support doctors in personalizing healthcare not only to the individual but also to their microbes.


Just as for medicine, the most relevant component to personalization in nutrition likely resides in our microbiome. Microbiome data can give us insights into how an individual’s digestive system responds to different types of food. Determining an individual’s microbiome composition is therefore likely to help health care professionals in creating personalized dietary recommendations.

Food Product Development

Foods can be designed to better feed and benefit the gut microbiota. In the context of personalized nutrition, ingredients and processing technology can be tailored to the specific needs of an individual and especially its microbiome.


Discover the many faces of #HumanMicrobiomeAction and #MicrobiomeAmbassador!

The Human Microbiome Action project connects microbiome experts from all over the world. Make sure to follow our @SciFoodHealth Twitter and LinkedIn channels for #HumanMicrobiomeAction to stay up to date about the most recent activities within the Human Microbiome Action project!
Interested in what is so exciting about the microbiome? Hear it first hand from our project partners and members of our Stakeholder Advisory Board under the hashtag #MicrobiomeAmbassador!