What exactly is the microbiome ?

You must have heard of the microbiome phenomenon. It’s about giving good bacteria a boost and reducing the impact of bad bacteria… Taking care of your microbiome is important, and here’s why.

Picture a world, with its leaders, rules, good guys, bad guys and communications systems. A world that lives in and on our bodies. Welcome to the universe of the microscopic microbiome! Of the infinitesimal, from bacteria to fungus, by way of other equally outlandish microorganisms. The microbiome is just about everywhere in our bodies… Much to our benefit! 

Two key figures to help you grasp its significance :

  • 1 to 2 kilos – is the average weight of the microbiome in adults
  • 10,000 billion – is the number of bacteria in our intestines

There is not one microbiome, but multiple microbiomes

Thanks to the runaway success of the book Gut: The Inside Story of Our Body’s Most Underrated Organ by Giulia Enders, we have all heard of this essential but often overlooked organ: the gut! But as well as the gut microbiome, the undisputed star among all the microbiomes, there are others which we are hearing about more and more. For example, the skin microbiome. It’s single-handedly responsible for reddening, premature signs of ageing and even teenage and adult acne! But do you know how significant the scalp microbiome is? Are you familiar with greasy roots and dry ends? And then there’s the vaginal microbiome… A disturbance in that microbiome could, for example, account for the onset of thrush or vaginal candidiasis infections, which can be foul-smelling and very unpleasant. In the microbiome family there is also the oral microbiome (from dental caries to gum disease, etc.), the mouth being the first point of entry into the body. Basically the microbiome is everywhere, from the scalp to the armpits!

The gut microbiome is the undisputed star

Ever since researchers started looking at the gut microbiome, new research leads have opened up on a great many ailments near or further removed from the belly. Perhaps you can’t seem to slim down? You’re prone to depression? You’re 30 and still have loads of spots? It could all be determined by your gut. How come? Through the brain-gut axis. Researchers have joined the dots between these two key organs in the body which are thought to communicate via a very sophisticated system through the vagus nerve (which we’re hearing more and more about), through the immune system and through the production of certain neuromediators (dopamine and serotonin). Basically, the brain and intestines send each other text messages all day long. “Are you OK?” “Yeah, fine” if all is well with your microbiome. “Hmmm, not really, this morning our host is acting up” in case of dysbiosis (if the microbiome is impaired). And it doesn’t take long for the resulting effects on your health to show up: from severe tiredness to bloating to a touch of diarrhoea, your belly is not happy at all. Furthermore, since the 1999 work of a certain Michael Gershon, a neurogastroenterologist at Columbia University (New York), the belly is referred to as the “second brain”.

Simply put, researchers are now studying the very close links between certain illnesses and the microbiome. In addition to diabetes and obesity, the scope is fairly broad. It ranges from so-called degenerative diseases (like Parkinson’s and Alzheimer’s) to autoimmune illnesses (like multiple sclerosis) and other conditions which on the face of it have nothing to do with the intestines, like autism. So we’re hearing more and more about the microbiome curing or preventing certain conditions.

The key role of bacteria in the intestines

What do the 10,000 billion bacteria located in the small intestine and colon do, anyway? First and foremost, logically enough, they ease digestion through a well-oiled mechanism. The bacteria cause certain types of fibre in the digestive tract to ferment. This fermentation produces fatty acids (such as propionate and butyrate) which serve as food for the colon’s cells, then as energy for the body. Thanks, bacteria!

But in addition to “mere” digestion, which is a hive of activity in itself, the microbiome also plays other fundamental roles. It protects the body from undesirable bacteria through a barrier effect. Basically, without a “Microbiome Health Pass” – move along now, you’re not coming in. Because the microbiome does guard the immune system of the entire body (and alerts the brain quick smart in case of invasion).

How do you keep your microbiome in tip-top condition?

Most importantly, you have to feed the animal (or rather animals) a good diet. To do so, go for prebiotics, probiotics and others whose names end in “tic”. 


A prebiotic

A prebiotic is a part of a foodstuff that we can’t digest (for example indigestible fibre, fructooligosaccharides, etc.) which stimulates certain bacteria. Simply put, it’s food for bacteria. Fruit, vegetables and pulses are brimming with it.

A probiotic

A probiotic is a microorganism (bacterium, yeast, etc.) that’s able to rebalance the flora of an ecosystem like that of the intestines, for example. That takes a good amount of it, though. It’s commonly referred to as “good bacteria”. The best-known probiotics are lactobacillus and bifidus. They are found in yoghurt and other fermented fare (sauerkraut, kefir and kombucha and also vinegar, gherkins and miso soup).

A postbiotic

A postbiotic is waste matter from probiotics, which creates an environment favourable to the development of good bacteria, a bit like potting soil for plants.

A symbiotic

A symbiotic is a combination of a prebiotic and a probiotic (in dietary supplements, for example).

As for supplementation

As for supplementation, take limited-time courses of probiotics, to be taken preferably in the morning on an empty stomach (and a long time before or after a hot drink). Just by the by, here are the names of the bacteria that can recolonise the gut: Lactobacillus (L. for short) and Bifidobacterium (B. for short): L. casei (defensis), L. acidophilus, L. gasseri, L. rhamnosus, B. lactis (B. regularis), B. bifidum (bifidus), B. longum, B. breve, B. animalis and B. humanis.

Note that each family of bacteria has its own features. For example, to remedy diarrhoea, take Saccharomyces boulardii or Lactobacillus reuteri. To treat eczema, again, take Lactobacillus reuteri. To remedy allergies, Lactobacillus caseii. If you find all this confusing, it’s best to ask your pharmacist for advice.

When should you take a supplement?

After chemo, after a course of antibiotics (moreover, it’s recommended to couple the treatment with a course of probiotics like Ultralevure® or Lactibiane®). You should also do so if you often have “stomach ache” and are prone to intestinal complaints, if you’re often ill (from a slight cold to gastroenteritis) or if you find it hard to lose weight.

Something approaching a microbiotic diet?

When it comes to diet, some foodstuffs are very microbiotic-friendly. The top spot of the podium goes to fermented beverages. Not beer, but kefir and kombucha (found in the organic aisle of the store). By their very nature, they rebalance the microbiome. Note that kefir contains much greater amounts of healthy bacteria than its cousin, yoghurt!

Other covert friends of the microbiome: garlic onion and leek, which feed our intestinal bacteria naturally. Another (often overlooked) part of the meal plan is pulses (lentils, chickpeas, dried beans), which are high in fibre. Konjac is another source de fibre (it’s delicious in spaghetti form!). In winter, don’t forget about sauerkraut (preferably from the chiller cabinet). Lastly, foods high in inulin (a type of prebiotic fibre) are beneficial: Jerusalem artichokes, salsify, asparagus, beets, etc.

The microbiotic diet, then, is very varied and fairly focussed on plant matter. Because it’s recommended to avoid red meat (not least because of the traces of antibiotics in it), saturated fatty acids and food additives. Another enemy of the microbiome is sugar. As well as making us pile on the pounds, it tends to throw off the balance of the gut microbiome, not least by promoting “bad” bacteria: those with pro-inflammatory action on the body.

Beware of stress

Stress is public enemy number 1 of the modern age, and is also thought to have an impact on the microbiome (remember that brain-gut axis). Moreover, at one time or another we have all had stress-related “stomach ache”. Because the stress hormone cortisol increases the permeability of the intestines. Simply put, the intestines, which get somewhat weakened, are then more easily subject to attack by bad bacteria. So for a microbiome in tip-top condition, consider pressing the pause button on yourself by attending meditation sessions, Pilates or yoga classes.

What should you make of fasting?

Since food is the fundamental pillar of the microbiome, you might wonder what effects fasting has on this ecosystem. Several studies lean towards proving that intermittent fasting may promote a healthy microbiome. So what’s the reason behind it? A lower intake of carbohydrates (sugars with pro-inflammatory action). All the more since this type of 16-hour fasting, by skipping breakfast or dinner, is thought to promote weight loss… This is a bonus for the microbiome, since when the scales tip the wrong way, inflammation and oxidative stress increase.

While a great many studies exist on the microbiomes of mice, there are still too few studies on humans planned at the present time. Note that in Turkey, a team of researchers conducted a study on Ramadan fasting and its effects on the microbiome. Result: an injection of “good bacteria” from the Bacteroides fragilis and Akkermensia muciniphila families: microorganisms that are painfully lacking in case of obesity. So what’s the reason given for this improvement in the gut microbiome? These species, which are particularly beneficial to our bodies, cope well with changes in diet. So use your good sense, eat as balanced a diet as possible and… Give your microbiome and intestines a rest from time to time!

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