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Probiotics and Athletic Performance

Sport Nutrition

By: Ashley Wong and Adrienne Ramos

Bacteria: The Good, the Bad and the Ugly   

Interestingly enough there is such thing as good and bad bacteria. In fact, a lot of gastrointestinal issues can stem from not having sufficient levels of good bacteria in your digestive tract.

Good bacteria? Yes, you heard me right. The difference is that good bacteria serves numerous biological functions to help stimulate our immune system and fight off unwanted infections.

In addition, Good bacteria can also help starve off inflammation and enable our bodies to digest and absorb nutrients. When helpful bacterium is able to thrive in our body, they can serve to protect us.

On the other hand, bad bacterium is the reason why bacteria as a collective has a terrible reputation. Bad bacterium is the culprit behind a number of diseases including strep throat, pneumonia, meningitis and various other infections.

This is also the reason why science has developed antibiotics to fight off unwanted infections and why we do our part to wash our hands and disinfect surfaces to prevent bacteria from further harbouring.

The bottom line is that both good and bad bacteria exists. More importantly, good bacteria is essential for our survival.

In this article, we will highlight two important nutrients: Prebiotic and Probiotics, and the potential benefits that they may have for athletes. We’ll also be answering the question that is probably on your mind. Should you be taking a probiotic or prebiotic supplement?

What is the gut microbiota?

Our bodies contain about 100 trillion bacteria. Within that gigantic number we have both good and bad bacteria that live inside of us. As a collective, this is known as your gut microbiota.

This bacteria is instrumental to our physiology, immunity digestion and absorption, brain health and risk for disease.

With trillions of bacteria in our gut and thousands of different species, it is important to note that everyone’s gut microbiota is unique.

Our gut microbiota continues to evolve throughout our lives, and factors such as genetics, age, environment, diet and medications can all influence the composition.

Of all the factors impacting our gut microbiome, diet may have the largest effect as it can quickly change the composition.

Prebiotics vs. Probiotics

With one letter differentiating the two, it is easy to get them mixed up.


Prebiotics are specialized plant fibres that essentially feed probiotics. As an example, fertilizers enhance the growth of plants, and similarly, prebiotics act as fertilizers to stimulate and promote the growth of healthy bacteria in your gut.

They are typically found in fruits and vegetables, and especially those that have complex carbohydrates like fibre and resistant starch.

These types of carbs pass through the digestive system to become “food” for the bacteria and other microbes to grow.


On the other hand, we have probiotics. From the Latin pro, and Greek βιοσ, the word essentially means “for life”.

Probiotics contain live organisms and have been studied for their various benefits such as digestive and immune system health.

Probiotics are found in certain fermented foods and dietary supplements.

So what’s the difference? Prebiotics serve as food to enhance the growth of good bacteria, and probiotics contain different strains of live organisms within themselves, that can directly add to the population in your microbiota.

Food sources that contain both prebiotics and probiotics are called symbiotic. They work together as a “team” to give you the most health benefits. It’s just like hitting two birds with one stone.

Where can I get Prebiotics and Probiotics?

Both prebiotics and probiotics are found in the foods we eat! Nonetheless, listed below is some, but not all!


  • Bananas
  • Onions
  • Garlic
  • Berries
  • Legumes
  • Beans
  • Peas
  • Oats
  • Jerusalem artichokes
  • Asparagus
  • Dandelion greens
  • Leeks
  • Apple skin
  • Chicory root


  • Miso soup
  • Sauerkraut
  • Kimchi
  • Kombucha
  • Kefir (dairy and non-dairy)
  • Pickled vegetables
  • Fermented cheeses, including Gouda

Can probiotic supplementation enhance my training?

Before you decide whether probiotics are or are not for you, you may want to read further!

I’ve mentioned this before, but I, myself, am a hard skeptic when it comes to supplements. Therefore, I will always preface my articles recommending that you seek guidance from your registered dietitian or doctor prior to starting any new supplements.

Probiotics for athletes is a sought-after topic within the realm of research. More specifically, the use of probiotic-based supplements utilized as a complementary method to help improve an athlete’s health.

Research has recognized probiotic supplementation have the potential to improve intestinal permeability, immune system efficiency, gut microbiota integrity and to reduce severity and incidence of upper respiratory tract infections (URTI).

So how can probiotics potentially benefit athletes?

1. Probiotics can improve gut and immune system health

Did you know that above 70% of our immune system is located within our gut? In fact, the mucosal lining of our gastrointestinal tract serves as the first line of defense against harmful bacteria or viruses.

If we were to imagine this like a battle, think of pathogens as the intruders (aka the bad-guys), and the mucosal lining as the first row of defending soldiers (good-guys). What could we do to help the first line-of defense?

The answer to that is probiotics!

Probiotics can alter the intestinal mucosal lining which prevents pathogens from binding. How? Various mechanisms of probiotics include producing antimicrobial agents that suppress the growth of unwanted ‘bad guys’

Another mechanism of probiotics is to compete with receptors and binding sites within the intestinal mucosal lining to prevent pathogens from binding. Super neat! It’s like we’ve given our soldiers (the mucosal lining) a shield (probiotics).

Of course, this is a simplified way to discuss a few of the many ways probiotics can help our immune system, but you can understand the point with this comparison!

Are GI issues impacting your running? Click here to read more about how to stop these annoying symptoms!

2. Probiotics can increase absorption of key nutrients

The gut is responsible for the digestion and absorption of nutrients.

In studies monitoring athletic populations, certain probiotic strains have shown to increase the absorption of various nutrients including amino acids (ie proteins).

How? Certain strains of probiotics can enhance the production of digestive enzymes which help the absorption of minerals and amino acids.  

For example, a specific strain studied: Bacillus coagulans, can enhance the health of cells within our gut lining by decreasing inflammation and encouraging optimal absorption within our villi.

The villi are finger-like projections in the small intestine where absorption takes place. The benefit of improved absorption of amino acids has been linked to an adaptive recovery post training.  

Numerous articles that studied triathlon and Olympic athletes concluded that the a common health benefit form anti-inflammatory strains of probiotics included enhanced recovery and shorten periods of fatigue.

Remember, amino acids are the building blocks proteins. Proper absorption of these key nutrients help trigger muscle building activity, preventing muscle damage, and kicking start the recovery phase.

3. Probiotics can reduce the incidence and severity of URTIs

In athletes, the use of probiotics is the most extensively researched form of defence for issues related to upper respiratory tract infections (URTI). And URTIs are one of the most common illnesses among athletes.

URTIs alter physiological capabilities reducing aerobic capacities, muscular strength and coordination. Some non-specific general symptoms include coughing, sore throat, nasal congestion, and headaches.

In athletes, symptoms appear more frequently during periods of increased training load, and during competition seasons. Beyond intense training load, it is important to note that several other factors contribute to increased risk of URTIs in athletes including stress, insufficient sleep, and a poor diet.

The use of probiotic-based supplements is utilized as a complementary nutritional strategy to help improve an athlete’s health. When studied amongst female swimmers and elite rugby players, there was a notable reduction in duration of symptoms and lower incidence of URTIs.  

As mentioned previously, our GI tract is a major pathway of entry of pathogens. Probiotics can help regulate the mucosal lining (our line of defense) by improving the activity of macrophages.

Think of macrophages as these specialized cells that can detect and engulf harmful bacteria. By engulfing the bacteria, macrophages are therefore destroying these bad guys. With an increased activity of macrophages, our body can mitigate harmful bacteria from proliferating.  

Ok, so now we know that probiotics can help support health and athletic performance. But, the question remains- do you need a supplement?

3 Tips for Probiotic Supplementation

1. Have a conversation with your doctor

Dosage and strain are important! If you have an existing health condition or compromised immune system, probiotics can do more harm than good. Additionally, taking a probiotic supplement ‘just in case’, can be at best a waste of money, or make gut health worse if the wrong product is selected.

Don’t make the mistake of consuming a strain of probiotics that is not sufficiently supported by research or is not meant to achieve the goals you have in mind. If you’re getting sick a lot during heavy training loads be sure to also look at other factors like sleep and nutrition before going straight to a supplement!

Remember, the effects may vary from person to person. Therefore, the specificity of different probiotic supplements can be better curated for your needs through the guidance of a qualified health practitioner.

2. Read the labels

Furthermore, there are few things to pay close attention! Take a look at the expiration date, the instructions for storage use, and at the CFU (colony forming unit).

The number you’d be looking for is between 1-10 billion CFU which is dependent on the recommended dosage from a qualified health practitioner. Products with less than that just don’t have enough CFUs to really make an impact. It would be kind of like tossing a teaspoon of water into a swimming pool. Pretty insignificant.

3. Purchase enteric-coated probiotics

Equally important is to pay attention to the way the capsules are coated. Enteric coated probiotic capsule ensures that the bacteria is delivered to their designated area, without being destroyed by the acidity of the stomach.

The Bottom Line

The bottom line is that good bacteria exists and is essential for our health! Probiotics for athletes is as an emerging topic in research, studies show it to be both safe and effective if utilized properly.

Likewise, probiotics and prebiotics in general are a great addition into your overall diet, and a lot of the time you might already be consuming them without even knowing. By consuming a varied, high fibre diet and taking other self care steps (like sleep and physical activity!) you can naturally support a healthy, functional gut microbiome. Supplements should only be taken if/when needed to help fix a specific health concern.

It’s important to remember that when seeking to make positive changes to your health, diet is just one of many factors. If you want to learn more about what you can do to support your gut microbiome, talk to a Registered Dietitian!

If you need help with your nutrition strategy for better performance, click here to learn more about working with me!