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Food, Global Health

Taking care of our symbiosis

Recent discoveries show that the links between microbiota and health are numerous. The good news is that there are ways to take care of our microbiota and preserve our interactions with it. A look at the key factors for a life in symbiosis.

Published on 05 October 2022

With the microorganisms in our gut, when all goes well, we are in a symbiotic, win-win relationship. We give our microbiota room and board, and in return it provides us with many services: it digests plant fibres and produces energy, it stimulates our immune system, it produces vitamins, it protects the intestinal barrier and sends important messages to the brain. This balance contributes to our general good health. It is therefore necessary to take good care of our microorganisms via their host, our body, in order to preserve the symbiosis. Because when this is not the case, we run the risk of being in a state of dysbiosis, which is associated with numerous pathologies: obesity, type 2 diabetes, irritable bowel syndrome, autism spectrum disorders, anxiety, depression, cirrhosis, multiple sclerosis, allergies and Crohn's disease. The list is long. On the other hand, symbiosis also has some “collateral” benefits. For example, it can limit the effect of food contaminants or prevent the risks of muscle wasting that seniors often suffer from as they age.

It is caused by external factors (like certain medications and alcohol consumption) or when the microbiota-host relationship is altered, resulting in a loss of bacterial diversity, an increase in pathogenic bacteria, an increase in the permeability of the intestinal barrier and, subsequently, a weakening of the organism and its immune function.

What does it take to be in symbiosis? The answer is simple (or almost): to have a rich microbiota, both in terms of the number of microorganisms and the number of different species, and a host that provides what the microbiota needs to maintain this diversity. So how do we maintain the richness of our microbiota? How do we give our microbiota everything it needs to maintain its diversity? In other words, how do we take care of our symbiosis? A four-step guide.

1 - By feeding it a varied, high-fibre diet

“25 different fruits and vegetables per week is what we should be eating” Joël Doré

Our microbiota is composed of microorganisms that do not all feed on the same thing. A varied diet, especially with fruit and vegetables rich in fibre and polyphenols, ensures the maintenance of bacterial diversity. Fibre is not digestible by human enzymes, but the bacteria of the microbiota love it. Is there an ideal diet for our symbiosis? Studies show that the Mediterranean diet is a good candidate: rich in fruit and vegetables, and therefore in fibre, with little red meat and the use of olive oil, which provides good quality fatty acids. Scientists also show that the “fast food and ultra-processed foods” diet has an indirectly deleterious effect on the microbiota because when fibre intake is reduced, the microorganisms are deprived of an important source of carbon and energy, and the microbiota then attacks the mucus of the intestinal wall to feed itself, weakening it and making it permeable to molecules and pathogens.

2 - By stimulating it during the first 1,000 days of life

Antibiotics in the early years can delay or alter the maturation of the microbiota and the immune system

The microbiota is established at birth. In utero, the baby is in a sterile environment, but as soon as the waters break, the baby's body (and not just its intestine) is colonised by the microorganisms it encounters, mainly those of its mother. “The development of the baby's microbiota during the first few years of its life is completely parallel to the maturation of its immune system”, explains Hervé Blottière, a microbiologist at the PhAN unit (Physiopathology of Nutritional Adaptations).
“If this maturation goes well, the baby will be in symbiosis between its cells and its microorganisms, but if the symbiosis is disturbed, there is a risk of infectious disease and immune disorders leading to the development of chronic diseases.”
So how do we take care of our symbiosis from birth? Through the food we eat, of course, in particular breast milk which itself contains a microbiota, and then through a varied diet. But also by exposure to microorganisms from an early age, those of the mother, during a vaginal delivery, and then those of the environment: playing in the dirt, having pets, all these factors play a role in the composition of our microbiota and the maturation of our natural defences.
Conversely, taking antibiotics in the early years can delay or modify the maturation of the microbiota and the immune system by reducing bacterial diversity, reducing beneficial bacteria, and even increasing resistant bacteria. While normality usually returns, there are some cases where a persistent change in the microbiota can be observed and which increases the risk of developing certain diseases.

3 - By having a healthy lifestyle

Because taking care of our symbiosis also means taking care of the host... To avoid dysbiosis, we need to take care of our intestinal barrier, and limit what could lead to inflammatory states or oxidative stress, and consequently increase the risk of colorectal cancer... For example, limiting the consumption of alcohol or meat products as it induces intestinal permeability: the cells of the intestinal barrier move apart and allow molecules to pass that would not be able to do so under normal circumstances.
Similarly, there is a release of cortisol into the bloodstream when we are stressed or anxious which also has an effect on the permeability of the intestinal barrier. The environment in which we live and exposure to various contaminants (in the air, water) also seem to influence the state of our symbiosis.
As for physical activity, it appears to be beneficial to the diversity of the microbiota and is therefore highly recommended!

4 - By supplying it with probiotics

Diversity of the microorganisms is the key factor in symbiosis.

Diversity of the microorganisms is the key factor in symbiosis. One possible way is to ingest them. This is the principle of probiotics. These are living microorganisms (bacteria or yeast) that are naturally found in fermented products, such as cheese, yoghurt, raw sauerkraut and bread.
They can be added to certain food products, yoghurts in particular, or consumed as a food supplement. Probiotics benefit our microbiota for two reasons. The first is that they naturally provide living microorganisms that increase the diversity of our microbiota. The second is that the fermentation process carried out by the enzymes of the microorganisms adds metabolites to the diet that are of multiple interest for the microbiota and more widely for our health. Studies furthermore show that probiotics, depending on the strain used, help digest lactose, can prevent or reduce diarrhoea linked to antibiotics or certain viral infections, and strengthen the intestinal barrier.

Amibiote baguette

baguette et tranche de pain

With a little help from science, researchers at the Micalis Institute have designed a bread, the Amibiote baguette, enriched with plant fibres, whose health effects have been demonstrated: control of cholesterol levels and improvement of insulin sensitivity in subjects at metabolic risk. 

The great challenge of fermented foods

Yoghurt, cheese, bread, sauerkraut, olives, wine, kefir, tofu, kombucha, kimchi..., will fermented foods take up more space on our plates? It is in any case a serious approach for obtaining health benefits from food. 

fermented food

Consumers are already getting started on it: “More and more people are fermenting their vegetables themselves”, but micro-trends aside, Marie-Christine Champomier-Vergès, Director of Research at the Micalis Institute, reminds us that there is a real challenge in developing fermented foods and in fully understanding the role of ferments in the health of our microbiota and our health in general: fermentation leads to the production of bioactive compounds, which, combined with the presence of probiotic bacteria in some of these products, can make them beneficial to health. Many questions arise: What are the interactions between food and microorganisms? What fermentation methods are there? With which strains? For what taste? For what nutritional effect? What are the interactions between the microorganisms in the food and our gut microbiota? And what about regulations? “Introducing microorganisms into our food, sometimes strains that are not usually consumed, is new and not harmless. In parallel with our research, we need to consider the regulations that will accompany these new products.” Science is taking on these questions.

A participatory science project, FLEGME, is calling on citizens in order to study fermented vegetables from artisanal production. A European network, PIMENTO, is gathering around these issues. Furthermore, and as part of the French Investments for the Future programme (PIA4), the “Ferments of the Future Grand Challenge” has been proposed by INRAE and ANIA (The French National Association of Food and Drink Industries) to maintain France's international leadership in fermented products.

  • Elodie Regnier

    Author / Translated by Alessandra Riva