Dysbiosis is when there is a problem with the diversity of someone’s gut bacteria. Though it is sometimes asymptomatic, dysbiosis may manifest in abdominal pain, bloating, and vomiting.

It can arise from infections, antibiotic use, or some aspects of a person’s diet. Doctors can treat dysbiosis with probiotics and fecal microbiota transplants.

This article examines dysbiosis, its causes and treatments, and more.

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The human gut contains large numbers of different bacteria. Dysbiosis occurs when the normal balance or activity of gut bacteria changes.

It can involve three main mechanisms:

  • loss of gut bacteria that benefit human beings
  • increase of gut bacteria that may harm human beings
  • loss of gut bacteria diversity

While dysbiosis may not directly cause symptoms, there is evidence that it can lead to symptomatic conditions.

In particular, a 2021 review discusses the potential impact of dysbiosis on gut health. This can lead to symptoms such as:

However, it is important to note that dysbiosis can remain asymptomatic for some time.

Researchers are beginning to uncover the many possible causes of dysbiosis, including:

A 2016 review discusses the possible dietary causes of dysbiosis. For instance, people whose diets are lower in fiber tend to have less diverse gut bacteria.

It also details its possible genetic underpinnings. For instance, mutations in the NOD2 and ATG16L1 genes may increase the risk of dysbiosis.

Additionally, research suggests that exposure to nicotine may worsen the effects of low dietary fiber on gut bacteria health. There is evidence that using nicotine can make people more prone to dysbiosis.

Risk factors for dysbiosis are things that make a person more likely to develop this condition. They are not necessarily causes of dysbiosis, although they may sometimes play a causal role.

Another 2021 review suggests that being born via a cesarean delivery is a risk factor for dysbiosis. This may be because children born this way have no exposure to the bacteria that colonize their parent’s birth canal.

Furthermore, these children are more likely to begin their lives in a sterile environment and to experience a delay in the start of breastfeeding or chestfeeding.

The same review suggests that exposure to antibiotics in early infancy may indicate a greater risk of dysbiosis and that early exposure to household pets can increase gut bacteria biodiversity.

To diagnose dysbiosis, doctors must request analyses of the diversity of an individual’s gut microbiome.

The gut microbiome is the totality of an individual’s gut bacteria. Experts will perform the analyses in the laboratory before sending the results to a person’s doctor.

Before this stage, doctors must obtain a sample of a person’s microbiome. They may either collect a stool sample or perform a biopsy of the small intestine.

Each approach has pros and cons. On one hand, collecting a stool sample is much easier and safer than performing a biopsy. On the other hand, stool samples do not contain all the bacteria types that may be present in a person’s gut.

Still, stool sample analysis remains the most popular approach for diagnosing dysbiosis.

The main premise of treatment is to increase gut microbiome biodiversity. Scientists have developed several ways of treating dysbiosis, including:

  • Fecal microbiota transplantation: Doctors begin by collecting and processing some feces from a healthy donor. They use a colonoscopy to introduce these feces into the gut of a person with dysbiosis. The bacteria in those feces can then start to repopulate the gut.
  • Probiotic therapy: Probiotics are specific bacteria and yeasts. Doctors can recommend these to people who have too few of certain good bacteria. Alternatively, doctors can recommend probiotics that might reduce harmful bacteria.
  • Microbial metabolic pathway therapy: Rather than acting on dysbiosis directly, this treatment uses pharmaceuticals to control the activity of gut bacteria. The aim is to increase the activity of healthy bacteria and reduce the activity of harmful bacteria.

Research into probiotics for dysbiosis continues to grow. There are specific strains for targeting the gut microbiome, but the Food and Drug Administration has yet to regulate products specific to this purpose.

There is no scientific data on which approach is best for treating dysbiosis.

The outlook for dysbiosis depends on which conditions it may be causing. Dysbiosis sometimes plays a role in the development of several conditions, including:

Furthermore, a 2016 review notes that dysbiosis may sometimes contribute to depression and schizophrenia.

Dysbiosis is an imbalance in gut bacteria. It may involve a loss of gut bacteria diversity, too many harmful bacteria, or too few beneficial ones.

Dysbiosis can arise from inflammation, infections, or antibiotic use. Some genetic mutations make people more prone to dysbiosis. Low fiber diets may also promote this condition. Additionally, being born via a caesarean delivery is a risk factor for dysbiosis.

Although it is sometimes asymptomatic, dysbiosis can cause abdominal pain, bloating, and nausea. It may also cause changes in bowel habits. Anyone with these symptoms should consult a doctor.

Collecting and analyzing a stool sample is the most common way to diagnose dysbiosis. Doctors can treat this condition with several techniques, including probiotic therapy and fecal microbiota transplantation.