Taking Care of Your Gut Microbiota for a Better Immunity

What is microbiota?  

The cells of our body constantly coexist with an extremely dense and varied microbial flora, the microbiota, a group of micro-organisms that live in a specific environment. There are different types of microbiota that colonize the surface of our skin and mucous membranes starting from our birth. They are found in the skin, mouth, vagina, lungs and so on. Together, they form the human microbiome.

The intestinal microbiota, also known as the second brain, is the most important one. It is composed of thousands of billions of micro-organisms that mainly live in the small intestine and colon.

The micro-organisms that make up the microbiota play an essential role in digestion processes. They break down complex foods that our bodies are incapable of digesting on their own, they help the body break down carbohydrates, proteins and sugars into nutrients and transform the fibers. The intestinal microbiota is also involved in the production of certain vitamins essential to our body, such as vitamin K or certain vitamins of the group B, like biotin. It helps maintain the integrity of the intestinal mucosa and its watertightness, and is involved in the process of recovering energy by fermenting undigested food.

Another major role of the intestinal microbiota is that it plays an important part in the functioning of the intestinal immune system.

How does the intestinal microbiota affect our immune system?  

The intestinal microbiota is made up of micro-organisms that are useful and at the same time potentially harmful. Most of them are symbiotic, i.e. when the human body and the microbiota benefit from one another, and some, in smaller numbers, are pathogenic, i.e. they encourage the development of diseases.

In a healthy body, pathogens and symbiotic agents coexist without any problem, in what is known as eubiosis. When the intestinal microbiota is well-balanced, the bacteria produce numerous metabolites and molecules known to be beneficial to the body.

But if this balance is lost, which may be due to infectious diseases, certain diets or the prolonged use of antibiotics or other bacteria-destroying drugs, dysbiosis occurs, stopping these normal interactions between pathogens and symbiotic agents. Dysbiosis is an imbalance in the bacterial ecosystem. The impact of dysbiosis on our health can be manifold: fatigue, diarrhea, constipation, bloating, digestive problems and immune deficiency.

As a result, our body can become more prone to disease.
Recent data suggests that dysbiosis could be an early factor in the development of certain neurodegenerative diseases such as autism spectrum disorder, Parkinson's disease and Alzheimer's disease. For the time being, these leads remain extremely early and need to be confirmed. An imbalance in the intestinal flora can also lower lung defenses and lead to bacterial superinfection. Hence the idea of boosting the microbiota of people who are prone to acute respiratory infections such as asthma or COPD.

What should you eat to boost your intestinal microbiota?

Everything we eat has an impact on the intestinal microbiota.
However, the microbiota is resistant. In the majority of situations, if an imbalance occurs and you quickly return to a healthy, varied diet or stop taking medication, the intestinal microbiota will return to equilibrium.

It is recommended that you eat a diet rich in fiber, include fermented foods in your diet, limit your intake of sugars and, if necessary, take prebiotics and probiotics.

Eat more fiber 

Dietary fiber can only be broken down and fermented by enzymes in the microbiota living in the colon.
Eating fiber limits the growth of certain harmful bacteria. The recommended daily intake for a good intestinal transit is around 30 to 45 g of fiber per day.

The main sources of fiber are vegetables, fruit, cereal, pulses and nuts. 

Fiber is divided into two categories: insoluble and soluble (in water). 

Insoluble fiber

Insoluble fiber facilitates bowel movements by increasing the volume and water content of the stool, which in turn cleanses the intestines by removing waste. Insoluble fiber is found in wholegrain cereals (wheat bran, rye), brown rice, leaves (cabbage), roots (beetroot), fruit and vegetables (green beans), starchy foods (potato skins), oilseeds (walnuts, almonds, etc.), pulses (green lentils, split peas) and raw cocoa powder. 

Soluble fibres

Among the main types of soluble fiber are prebiotics (composed of inulin and oligofructose), which stimulate the growth of health-promoting intestinal bacteria. They are found mainly in legumes (lentils, chickpeas, white, kidney and black beans), chicory, garlic, onions, apples, oats, linseed, barley, rye, psyllium, potatoes, carrots, strawberries, citrus fruit, konjac or burdock root and seaweed. Their consumption should be limited in cases of irritable bowel syndrome (IBS) or diverticulosis.

Include probiotics in your diet

Probiotics are living organisms, usually bacterial strains naturally present in the intestinal flora. Taking probiotics in the form of food supplements helps enrich the intestinal flora. The most commonly used probiotics are Lactobacillus and Bifidobacterium.

Depending on the strain used, they are thought to help digest lactose, prevent or reduce diarrhea associated with antibiotics or certain viral infections, and strengthen the intestinal barrier. Various types of products of varying quality are available on the probiotics market. However, despite their highly promising efficacy, they haven't been subject to much research yet.

Eat fermented foods 

It is also a good idea to include fermented foods such as sauerkraut, kimchi, miso and tempeh, as well as fermented dairy products such as yoghurt, sour sauce, buttermilk and fermented butter in your diet. There are also fermented drinks such as milk or kefir, kombucha, mead, boza and ginger beer.

These fermented foods contain their own probiotics. Their principle is to use clusters of micro-organisms to ferment the liquid. Fermented foods boost the immune system.

Limit your consumption of sugar 

A diet rich in sugar could unbalance the intestinal microbiota and encourage harmful bacteria that have an inflammatory effect.

On a day-to-day basis, it is advisable to gradually reduce your sugar intake, and avoid ultra-processed products and ready-made meals that contain a lot of sugar. You should also be wary of sweeteners, as recent studies have suggested that regular consumption of some of them can disrupt the functioning of the intestinal microbiota.

You can strengthen your intestinal microbiota by improving your lifestyle. Good quality sleep, regular physical activity and drinking enough water are all essential for maintaining a balanced microbiota. These healthy lifestyle habits help create an environment conducive to the proliferation of good intestinal bacteria. 

It is also important to avoid inflammatory conditions or oxidative stress linked, for example, to consuming too much alcohol or red meat, which will lead to intestinal permeability.

Chronic stress can also have harmful effects on the microbiota. Stress management techniques such as meditation, yoga or deep breathing can help maintain a healthy balance in the gut and support the immune system.

In conclusion, taking care of your microbiota is a key strategy for boosting your immune system. A well-balanced and varied diet rich in fiber, combined with stress management and a healthy lifestyle, can help maintain a diverse and functional microbiota.

A healthy gut is characterized by a highly diverse microbiota, but there is no universal marker of gut health. What is normal for one individual is not necessarily normal for another.

You should always see your doctor or pharmacist before taking food supplements based on prebiotics or probiotics, as some can be dangerous, especially if you are undergoing immunosuppressive treatment.

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