In the body of every person there are on average 10 trillion human cells. What most people don’t know, however, is that our bodies are also home of 10 times more cells of other microorganisms, such as bacteria, fungi, viruses and others. They are collectively known as our microbiome and have an important role in a number of processes, such as nutrient metabolism, regulation of the immune system and even our emotional state.
Microorganisms live across the whole body, but a large portion of them are found in the digestive system and in particular in the large intestine. This is not surprising, as bacteria have an important role for digestion. They help in the fermentation of otherwise non-digestible dietary fibres and complex carbohydrates into short-chain fatty acids. They also aid the synthesis of important substances such as enzymes, vitamins (e.g. B vitamins) and amino acids.
Interesting: On average we have 23,000 human genes and over 3 million microbial! Through their metabolism microbes produce thousands of substances – some are beneficial for the human body, while others can be toxic.
Why is it important to have a diverse microbiome?
It is essential to have a diverse microbiome – imagine the diversity of vegetation in the Amazon rainforest! The microbiome forms at birth, continues to develop as we grow and is affected by a number of factors, such as diet, stress, environment and medications. If the microbial balance is disturbed, this can lead to dysbiosis, reduced diversity and an increase in the number of pathogenic or ‘bad’ bacteria. Studies have found a connection between reduced microbiome diversity and a number of chronic conditions, such as inflammatory bowel disease, psoriasis, arthritis, Chron’s disease, atopic dermatitis and obesity. One study with twins showed that if microbiome from the obese twin is transferred to mice, they also gain weight, which doesn’t happen if microbiome from the lean twin is transplanted.
Interesting: Breastfeeding is thought to be beneficial for stimulating the ‘good’ bacteria in the microbiome of the baby, such as Bifidobacteria. Children with more diverse microbiome develop less allergies when they grow up.
How does the microbiome affect our mental health?
Besides our physical health, the microbiome also influences our emotional and mental health. Some species of bacteria help in the production of serotonin, which is an important neurotransmitter in mood regulation (90% of serotonin is produced in the gut versus less than 10% in the brain). Another European study shows that people with depression lack two species of bacteria (Coprococcus and Dialister), which are connected to a pathway for dopamine production, as well as the anti-inflammatory substance butyrate. However, it is still unknown how exactly all the substances produced by the microbial flora affect the brain.
How can we care for our microbiome?
Although there is still a lot to learn about the microbiome, there are some things we can do to increase the diversity and the number of ‘good’ bacteria in our bodies.
- Eat diverse foods, which leads to a diverse microbiome. Beans and fruit contain dietary fibre, which stimulate the growth of Bifidobacteria. Wholegrains and vegetables are also beneficial.
- Eat fermented foods, such as yoghurt, sauerkraut, kimchi and kefir. They contain ‘good’ bacteria, such as Lactobacilli, which help reduce the number of pathogenic bacteria.
- Limit the intake of artificial sweeteners, such as aspartame. They stimulate ‘bad’ bacteria, such as Enterobacteriaceae.
- Eat prebiotic foods, which feed and promote the growth of ‘good’ bacteria. These foods include bananas, apples, oats, artichokes and asparagus.
- Eat foods rich in polyphenols, which are contained in green tea, dark chocolate, olive oil and red wine.
- Take probiotic supplements, which contain live strains of bacteria and can be beneficial in normalising the microbiome after a state of dysbiosis. However, it is important to consult with a doctor before taking any supplements.
- Be careful with antibiotics and only take them when it is a medical necessity. They can kill both the ‘bad’ and the ‘good’ bacteria.
The interdependence between humans and their microbiome is symbiotic and complex. Although it is a topic of many scientific studies, there is still a lot we don’t know about how the different metabolic processes of the bacteria in our bodies influence our overall health. That is why before making any radical changes in diet or lifestyle, please consult with your doctor!