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When the balance of our microbiota is disrupted — a condition known as dysbiosis — our body suffers. An imbalance means a decrease in beneficial bacteria, a decrease in microbial diversity, or an overgrowth of harmful microbes (1). The causes of this dysbiosis can be diverse (we will see them in the next section), but its consequences are usually similar: digestive discomfort and impact on general health.
In the gut, a damaged microbiota can lead to chronic digestive problems. For example, dysbiosis has been linked to conditions such as irritable bowel syndrome, inflammatory bowel disease (colitis, Crohn’s), and even an increased risk of infections such as antibiotic-associated diarrhea or Clostridioides difficile (2). When the intestinal barrier is altered, it is easier for pathogens or inflammatory substances to irritate the mucosa, causing inflammation and damage.
But the effects aren’t limited to the gut. Numerous studies link unbalanced microbiota to metabolic and systemic diseases. For example, dysbiosis has been observed in people with obesity, type 2 diabetes, and cardiovascular disease, suggesting it may influence energy metabolism and glucose regulation (2). Likewise, unhealthy microbiota has been linked to autoimmune disorders and allergies, due to its role in immune modulation.
Even in the mental realm, an alteration in the intestinal flora could contribute to psychological symptoms. Emerging studies find a correlation between dysbiosis and a higher incidence of depression, anxiety, and even cognitive decline (2). This could be explained by the increase in pro-inflammatory substances and the reduction in beneficial metabolites that occur when “good” bacteria are scarce.
In short, when the microbiota is unbalanced or damaged, we feel it: digestive discomfort appears and susceptibility to various diseases increases. As studies show, an altered intestinal composition has been linked to the development of numerous inflammatory and infectious diseases (3). Therefore, maintaining the balance of our microbes is essential to preserve overall health.
Factors that can unbalance our microbiota
It is normal for our microbiota to fluctuate over time, but certain lifestyle and environmental factors can cause marked imbalances in its composition. Among the main triggers of Intestinal dysbiosis we find:
- Unhealthy diet: Diet is perhaps the most influential factor throughout life (3). A typical Western diet, high in sugars, saturated fats and ultra-processed foods and low in fiber, can negatively alter our microbiota. For example, excessive consumption of simple sugars and junk food reduces microbial diversity and promotes bacteria associated with inflammation (1). In contrast, diets high in fiber favor beneficial bacteria (as we will see later). The variety and quality of what we eat directly shapes our intestinal ecosystem. If you want to know a little more about ultra-processed foods and which additives you should avoid, take a look at this article .
- Antibiotic (and other medication) use: Antibiotics are lifesaving drugs for fighting bacterial infections, but their indiscriminate use also “drains” the good bacteria in the gut. Antibiotic treatment can drastically reduce the normal microbiota population and allow resistant or harmful microorganisms to proliferate. The result is often diarrhea and discomfort (such as antibiotic-associated diarrhea). Other medications, such as some antacids, laxatives, or even sweeteners and food additives, can also negatively impact the microbial balance (1). It is essential to take antibiotics only when truly necessary and always under medical advice (4).
- Chronic stress: Body and mind are connected to the gut. Prolonged psychological stress can alter intestinal motility, the secretion of digestive juices, and induce changes in the microbiota through stress hormones (4). Various studies in humans and animal models have shown that sustained stress can reduce bacterial diversity and favor the growth of harmful microbes, contributing to a state of dysbiosis (4). This helps explain why stressful situations are often associated with flare-ups of colitis, irritable bowel syndrome, or simply “stomach upset.” In this article we give you some tips and tricks to reduce or even get rid of your stress!
- Unhealthy lifestyle habits: Sedentary lifestyle, lack of exercise, tobacco, and excessive alcohol consumption also affect microbiota. For example, smoking has been linked to altered microbial compositions in both the gut and lungs, promoting harmful bacteria and inflammatory responses (2). Lack of physical activity, on the other hand, may contribute to lower bacterial diversity; in fact, highly active individuals (such as athletes) often display a more diverse microbiota than sedentary individuals, suggesting that regular exercise has a positive modulating effect (we will explore this in best practices).
- Other factors: Host genetics can predispose to certain microbial compositions, although environment and diet are thought to play a larger role in determining the microbiota (4). Age also plays a role: in old age, the microbiota tends to lose diversity and certain beneficial groups, which may contribute to immunological fragility in older adults. Likewise, extremely sterilized environmental hygiene (lack of contact with nature, excessive use of disinfectants) could limit exposure to microorganisms and reduce the richness of the microbiota, according to the “hygiene hypothesis.” In contrast, living with pets or in rural environments diversifies the microbes we come into contact with, potentially enriching our flora.
In conclusion, an unbalanced modern life can take its toll on our microbes. Poor diets, unnecessary antibiotics, stress, and a sedentary lifestyle have all been identified as factors that promote bacterial imbalance (4). The good news is that just as we can harm our microbiota, we can also nourish and restore it through changes in our habits. Let’s see how to identify a possible imbalance and what you can do to keep these important life partners in harmony!
Main symptoms of an unbalanced intestinal microbiota
How do you know if your microbiota isn’t quite right? There are warning signs that may indicate an intestinal imbalance. Among the symptoms further common causes of dysbiosis we found :
- Digestive discomfort and disorders: Excessive gas (flatulence), abdominal bloating (feeling of a bloated stomach), and changes in intestinal transit are often the first signs. Both recurrent diarrhea and chronic constipation can be related to altered flora. Many people with dysbiosis report heavy digestion, colic, or frequent abdominal discomfort without apparent cause (2). Gas production or even halitosis (bad breath) can also occur due to abnormal fermentation in the intestine.
- New food intolerances or worsening symptoms: An unbalanced gut can become hypersensitive to certain foods. For example, some people develop lactose or gluten intolerances associated with altered microbiota. Food sensitivities may also develop. that were previously well tolerated. If you notice that almost everything suddenly makes you feel unwell, your flora could be involved.
- Drops in immunity and frequent illnesses: Given the role of microbiota in the immune system, its imbalance can manifest itself in recurrent infections. For example, repeated candidiasis, frequent urinary tract infections, or constant colds could be associated with a weakened flora that no longer adequately controls pathogens. Furthermore, an altered microbiota can contribute to low-grade systemic inflammation, related to allergies or exacerbation of autoimmune conditions. In this article, we explain what this inflammation consists of and how to prevent it.
- Skin disorders and allergies: There is a well-known gut-skin axis. Dysbiosis can be reflected in skin problems such as acne, eczema, dermatitis, or worsened psoriasis. A relationship has also been observed between intestinal imbalances and more pronounced food or environmental allergies. For example, some studies link early dysbiosis with a higher risk of atopic dermatitis in infants.
- General symptoms such as fatigue and mood swings: Many people with microbiota imbalance report chronic fatigue, lack of energy, and even brain fog. This could be due to decreased production of certain vitamins, or the low-grade inflammation caused by dysbiosis. Likewise, given the gut-brain axis, it’s not surprising that emotional symptoms may arise: anxiety, depression, irritability, or sleep disorders can accompany chronic gut problems. In fact, some patients with major depression have been observed to have altered microbiota, suggesting a two-way connection between the two systems.
It’s important to note that these symptoms can have multiple causes, and the microbiota is only one piece of the puzzle. However, if you experience several of these issues persistently, it’s worth paying attention to your gut health. A health care professional can assess imbalances (including through stool analysis that examines microbial composition) and recommend measures to restore balance.
In our next article, we’ll give you guidelines and tips for restoring and maintaining balance in your microbiota. Don’t miss it!!
Article references
- Hrncir T. Gut Microbiota Dysbiosis: Triggers, Consequences, Diagnostic and Therapeutic Options. Microorganisms. 2022 Mar 7;10(3):578. doi :10.3390/microorganisms10030578. PMID: 35336153; PMCID: PMC8954387.
- Alagiakrishnan Kannayiram, Morgadinho Joao, Halverson Tyler: Approach to the diagnosis and management of dysbiosis. Frontiers in Nutrition Volume 11 – 2024. https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2024.1330903 DOI=10.3389/fnut.2024.1330903 ISSN=2296-861X
- Thursby E, Juge N. Introduction to the human gut microbiota. Biochem J. 2017 May 16;474(11):1823-1836. doi :10.1042/BCJ20160510. PMID: 28512250; PMCID: PMC5433529.
- Madison A, Kiecolt -Glaser JK. Stress, depression, diet, and the gut microbiota: human-bacteria interactions at the core of psychoneuroimmunology and nutrition. Curr Opinion Behav Sci. 2019 Aug;28:105 -110. doi : 10.1016/j.cobeha.2019.01.011. Epub 2019 Mar 25. PMID: 32395568; PMCID: PMC7213601.