Infographic: dos and don'ts for a healthy microbiome
The ecosystem in our gut has changed so much over time that some researchers are already talking in terms of an "industrial microbiome". Following a few basic rules can help restore biodiversity inside us.
The following text is an excerpt from the "European Food Trends Report 2021”, that can be ordered on our website.
As the use of pesticides in the fight against vermin, weeds and poor harvests has enabled agriculture to make significant advances, medicine has likewise enjoyed considerable success combating pathogens: Most people were still dying of tuberculosis, pneumonia and other infections in 1900. Antibiotics and better hygiene have however taken the dread out of many contagious diseases.
The parallels do not nonetheless end here. Like farming, medicine has been asking itself for a long time whether we have possibly taken things too far? Have we ultimately declared battle not just on vermin and pathogens, but also done for many useful organisms? Have we upset the balance of entire ecosystems? These questions are not new for our environment. They are however unfamiliar where humans are concerned: man as a sickly ecosystem, acting as the host, so to speak.
Humans as hosts We have actually been living with our microbes in a successful partnership that has been going on for thousands of years: one host and many guests who live off what the host serves up. In return they make metabolic products that affect the immune system, the lungs and the heart and support their functions – this even includes the brain. If the host however serves too much alcohol, sugar, or meat, the clientele will change. If some guests then do not like being faced with, say, antibiotics or excessive hygiene and get thrown out, the congenial atmosphere at the venue may turn sour. And there is reason to believe that certain modern-day ailments can also be attributed to a bad atmosphere in the host’s own microbial world.
It has been established that the microbiome of inhabitants in industrialised countries, and in particular urban dwellers, contains significantly fewer species of microbe than in people who live closer to nature or at least out of town. And there are increasing indications that this lack of species diversity, above all affecting the gut, could be behind the significant rise in autoimmune disorders in industrialised regions over recent decades, for example allergies and inflammatory conditions. They could ultimately be the manifestation of a disturbed ecosystem, an ecosystem that is not sufficiently interwoven with other ecosystems, not sufficiently entangled.
Species extinction in the gut
This ecosystem has at all events undergone such major change over past years that some re- searchers are now talking about an «industrial microbiome». This means that many useful microbes are hardly present in the gut or are absent altogether. One reason for this is a lack of rough- age for them. Although it cannot be digested by humans, it is an excellent source of nutrition for numerous bacteria. If there is a shortage of this so-called prebiotic in the diet of individuals who do not eat enough plant-based foods, microbiome diversity will decline and their state of health will generally also suffer.
There is not normally enough fibre in our modernday diet, which often contains excessive levels of simple carbohydrates and fats. They adversely affect the composition of the microbiome, as is also the case with frequent use of additives, e.g. emulsifying agents and sweeteners. Studies have demonstrated that both can encourage inflammation of the bowel and obesity. People who consume a lot of sweeteners also often have a different composition of the microbiota, as occurs in type 2 diabetics.
A depleted microbiome is no longer able to perform many of its original functions to the full extent. We thus also talk about «ecosystem services» in relation to our microbiome, a bit like ecosystems such as deciduous forests for example. With an intact microbiome this would be for instance breaking down indigestible food, warding off pathogens or even releasing happiness hormones.
Renaturation of the bowel
What should be done if all these vital services no longer function properly? In nature we often try – with greater or lesser success – to bring back species that have disappeared and to rewild ecosystems. And this is exactly what we are at- tempting to do for humans.
One such renaturation measure is the faecal transplant as mentioned above. This involves processing a stool sample from a healthy volunteer and then transferring it to the gastrointestinal tract of sufferers, either in capsule form or via colonoscopy. However, therapeutic successes with diseases such as chronic intestinal inflammation, irritable bowel syndrome, multiple sclerosis or autism have to date generally been elusive or were merely short-lived. Instead of transferring an entire composition of foreign species to a disturbed ecosystem, it may thus be more helpful to «rewild» an ecosystem bit by bit: by ensuring more contact with microbes from our environment, plenty of exercise, less stress and, in particular, by supplying the most important microbes in our gut with adequate nutrition (see figure).
Our food also has a microbiome of its own
It however does not just seem important here which products we consume, but also how they have been produced. Plants too have a microbiome that has a determining influence on their health, nutrient content and yield. So as antibiotics can radically change the human intestinal microbiome and its functioning, the use of herbicides, fungicides and pesticides in food production has a dramatic impact on the plant microbiome in the soil and on the fruit and vegetables that we eat. The increasing use of fertilisers and herbicides, soil erosion, and climate change also affect microbial biodiversity and contribute to the loss of large areas of arable land and their microbial populations. This nowadays deprives arable crops of many their key symbiotic partners, which produce or boost the content of vitamins, minerals, antioxidants and other metabolic products that benefit both plant and human health. This is just one of the many examples of how humans and their environment are entangled organisms. «Humans are an ecosystem fully integrated into the landscape», is how neuroscientist and philosopher Tobias Rees of California’s Berggruen Institute sums up these complex interconnections.