Wednesday, August 17

The world against your bacteria: the main killers of your microbiota

The microbiota in our gut is an extremely complex ecosystem of trillions of microorganisms belonging to hundreds of different species of bacteria, not counting viruses, protozoa, archaea, and fungi.

How the pandemic has affected our microbiota

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These fellow travelers live in symbiosis with us, and without their collaboration we could not live. They digest food for us, make vitamins, hormones, and neurotransmitters, and when their populations are destabilized, they cause all kinds of diseases, from diabetes and obesity to depression.

In the same way that the planet’s ecosystems are threatened by humanity, the ecosystem of our body is also under pressure from what we do in our modern lives: what we eat, the medications we are prescribed, the stress we suffer and pollution. in our environment.

It’s as if everything around us is designed to kill the good bacteria in our gut and make way for the bad. Therefore, to protect ourselves, it is important to know what the main dangers are for our microbiota. Our health is in it:


The most prescribed antibiotics and those that are even consumed without a prescription by many people are the broad-spectrum ones, that is, they are capable of killing a wide variety of bacteria. This includes bacteria that can be harmful such as E. coli, strep or staph. This indiscriminate use is associated with the appearance of superbugs resistant to antibiotics.

Also, a review of studies observed that antibiotics such as doxycycline or clarithromycin also destroy bacteria that have a protective and anti-inflammatory effect, such as bifidobacteria and lactobacilli. Although the bacteria recovered within weeks in most people, in other people the negative effects of antibiotics on the microbiota could last from 2 to 6 months.


Everything we eat affects our microbiota, favoring the proliferation of some bacteria and causing others to disappear. The problem is when the bacteria that disappear are the good ones, and that is exactly what happens when we eat sugar.

In a study with mice, it was found that a high level of sugar in the diet caused changes negative in the composition of the microbiota. Specifically, there was a reduction in the populations of Bacteroidetes, which we need for protection against cancer, and an increase in Proteobacteria, which are present in small quantities in healthy people, and when they increase they are a dysbiosis sign and inflammation.


Omeprazole, and other drugs called proton pump inhibitors, are meant to reduce the amount of acid in the stomach to treat people who suffer from gastric reflux or heartburn. Unfortunately, especially in Spain, it is consumed in large quantities without a prescription, and it is a disaster for the intestinal microbiota.

One of the functions of stomach acid, in addition to digesting food, is to eliminate possible harmful bacteria. When there is not enough acid, these bacteria can pass into the intestinecrowd out beneficial bacteria such as bifidobacteria, and cause staph or strep infections.

the contraceptive pill

A curious effect of antibiotics is that they can affect the effectiveness of hormonal contraceptives in women. This is because the bacteria in the gut have an important role in the synthesis of hormonesincluding estrogens and progesterone.

The reverse also occurs and it has been seen that oral contraceptives alter the microbiota and can cause diseases such as irritable bowel syndrome and Crohn’s disease in certain cases.


Ibuprofen, aspirin, naproxen or diclofenac are the most popular of the so-called nonsteroidal anti-inflammatory drugs, and as with other over-the-counter drugs, there are people who consume them daily.

The use of these anti-inflammatories can modify the composition of the intestinal microbiota and cause the increase in gram negative bacteria, which are the ones that release endotoxins that affect the intestinal mucosa and produce inflammation. The use of probiotics or even yogurt in conjunction with these medications can mitigate their negative effects.

Lack of polyphenols

The above compounds negatively affect the microbiota, eliminating the beneficial bacteria and causing the harmful ones to proliferate. However, there are some compounds that do exactly the opposite: polyphenols. These substances are part of the chemical defenses of plants, and it has been seen that more than antioxidants in themselves, they stimulate our internal antioxidants.

However, it is now known that the other beneficial effect of polyphenols is modulate gut bacteriaas they increase the populations of bifiidobacteria and lactobacilli, which protect the intestinal barrier, and other bacteria with anti-inflammatory effects.

The problem, then, is when polyphenols are lacking in the diet. The foods richest in these substances are, among others, intensely colored vegetables, forest fruits, herbs and spices, olive oil, dark chocolate and nuts and seeds.

What is all this based on?