How Probiotics Work: Debunking Myths and Understanding their Value

What is the microbiota and what does it do?

Our organs, such as the gastrointestinal system, vagina, and skin, are home to thousands of different microorganisms, including bacteria and yeast (microscopic fungi). Normally, all these microorganisms live in harmony and contribute to maintaining the body’s health. The term "microbiota" is used to refer to this set of microorganisms.

We do not yet know all the effects of the microbiota in the body, but we do know that it participates in many processes. For example, the gut microbiota helps with proper digestion of food, a healthy immune system, and the synthesis of certain vitamins. New evidence suggests that gut health may play a role in skin health.

What factors can disrupt the microbiota, and what can be the consequences?

The microbiota contains both microorganisms that are good for your health and others that can cause infection (pathogens). When all is well, there is a symbiotic relationship between the various bacteria, yeasts, and other microorganisms, thus preventing the pathogens from causing an infection.

A disruption to the microbiota can result in an imbalance of microorganisms, with some becoming less abundant or proliferating more than they should. This can have implications for your health. The following are a few examples: 

• A change in pH balance in the vagina can impact the vaginal microbiota, which can lead to the development of a vaginal infection (yeast or bacteria).
• An imbalance in the gut microbiota can result in diarrhea or, conversely, constipation.
• Studies suggest that changes in the gut bacteria may contribute to obesity and type 2 diabetes.
• An unbalanced microbiota may be associated with the occurrence of certain cancers, particularly colon cancer.
• An imbalance in the gut microbiota seems to play a role in the inflammation associated with inflammatory bowel diseases, such as irritable bowel syndrome and Crohn's disease. 

There are a number of factors that can disrupt the microbiota, including:

• The use of certain medications, such as antibiotics;
• Smoking;
• Poor eating habits;
• Certain diseases;
• Environmental factors.

What is a probiotic and how does it work?

A probiotic is a live microorganism that confers a health benefit to the person who consumes it if taken in sufficient amounts.

There are thousands of bacteria that make up our microbiota, but the most common ones used in probiotics are from the Bifidobacterium and Lactobacillus genera. These have been studied the most. Some probiotics contain yeasts, usually from the Saccharomyces family.

It is a common misconception that probiotics have a significant impact on the body's microbiota. In fact, the bacteria (or yeasts) contained in probiotics usually do not settle in the body and do not have a major impact on the microbiota's composition. Rather, they support the work of the other microorganisms, for instance by assisting in the digestive process or interacting with the immune system. Consequently, probiotic treatment may only be required for a few days when a one-time problem arises or may need to be taken over an extended period to treat a chronic health condition.

When should you take a probiotic?

Probiotics have been shown to be beneficial in several health conditions, such as:

• Irritable bowel syndrome
• Crohn's disease
• Ulcerative colitis
• Chronic constipation
• Certain liver diseases
• Weight management
• Colic in babies
• Vaginal bacterial or yeast infections in women

It is currently unclear whether probiotics are beneficial for healthy individuals. The only established use of probiotics in this context is for the prevention of diarrhea, for example in cases where antibiotics are administered or in the prevention of traveller's diarrhea. 

In some cases, probiotics may be used on their own, but they're typically used alongside regular treatment for chronic diseases.

Each person's microbiota contains a unique mix of microorganisms. Therefore, response to probiotic therapy will vary from person to person.

How do you choose the right probiotic?

It's important to choose a probiotic carefully because there are many different strains of bacteria (or yeast) and only specific strains have been shown to be beneficial in certain situations.

What exactly is a strain? Bacteria are grouped into large categories called genera. Each genus may have several species, and each species may have many strains, for example Lactobacillus (genus), rhamnosus (species), GG (strain), or Bifidobacterium (genus), lactis (species), CNCM I-2494 (strain).

To choose the right probiotic, you've got to make sure that the strain(s) it contains has been shown to help with the health problem you want to treat.

Our understanding of probiotics keeps improving, and new products are regularly launched. To find the right one for you, it's best to check a reliable and up-to-date source of information, such as the guide from the Alliance for Education on Probiotics, which is updated annually by Canadian experts. Your pharmacist is also there to help you find the product that meets your needs!

Once you've selected the right probiotic, it's important to take the correct dose to ensure you have enough probiotics to see results. As with any medication, if you don't take enough, you may not get the benefits you're looking for. And if you take too much, you may experience unwanted side effects, especially if you have health problems.

It's also important to make sure you follow the storage guidelines, because the probiotics need to stay alive to work. Some probiotics can be stored at room temperature, but many products need to be kept in the fridge. 

Which foods are a good source of probiotics?

Fermented foods with live cultures, such as yogurt, kefir, kimchi, and sauerkraut, are a great source of probiotics and should definitely be part of a healthy diet. However, because we don't usually know exactly which strain of microorganisms they contain and in what amount, these foods are not generally recommended for use in treating a health problem.

Are probiotics supplements right for everyone?

No, some people should not take probiotics supplements, especially those with weakened immune systems. If you have health problems, always seek professional advice from your pharmacist or healthcare team before taking any type of supplement, including probiotics.

What's the difference between a probiotic and a prebiotic?

A prebiotic isn't a microorganism. It's a substance found in food that we can't digest, such as the insoluble fibres found in many fruits and vegetables. The microorganisms that make up the microbiota digest these substances for us, and in doing so, they release metabolic products that are good for our health. In essence, prebiotics are food for the microbiota.

Since prebiotics are naturally found in foods, make sure you eat a varied diet rich in complex fibres such as whole grains, fruits, and vegetables to nourish your microbiota.

Got questions about probiotics? Your pharmacist is there for you!

Not sure if a probiotic is right for you? Don't hesitate to reach out to your pharmacist. They can recommend a product that will be appropriate for your needs or refer you to another resource if probiotics are not the best option for you.