~ Annie Bothma, Elite Athlete, IOPN Performance Sports Nutritionist (EQF Level 7. Masters), Running & Strength Coach
Athletes often endure gastrointestinal (GI) distress and fatigue, especially during endurance events like marathons. These issues, resulting from increased intestinal permeability, allow gut bacteria to leak into the bloodstream, triggering inflammation and fatigue. This can hinder athletic performance and impact recovery. Probiotics, or “good” bacteria, offer a potential solution by strengthening gut health, reducing inflammation, and even possibly enhancing performance.
This blog post summarizes a systematic review from the Journal of the International Society of Sports Nutrition, titled “Do Probiotics Mitigate GI-Induced Inflammation and Perceived Fatigue in Athletes?” This review examines the impact of probiotics on gastrointestinal health and fatigue in athletes, exploring its effects on enhancing performance and supporting recovery.
Understanding Probiotics
First things first! Before diving into the research details, let’s start by defining probiotics:
Probiotics are live micro-organisms which, when consumed in adequate amounts, offer a health benefit to the host.
Evidence suggests that probiotics may enhance gut and systemic immune function by improving low-grade inflammation and promoting mucosal integrity of the endothelial lining. Furthermore, probiotics may also aid in maintaining the composition of the microbiota, which encompasses a collective of protozoa, archaea, eukaryotes, viruses, and predominantly bacteria that live symbiotically within humans. Several studies have shown that probiotics supplementation could improve immune function in fatigued athletes and reduce upper respiratory tract illness (URTI), GI symptoms and gut permeability.
The gut-brain axis is a powerful communication pathway linking the gut and the brain, influencing both physical and mental health. Through this connection, gut bacteria play a role in regulating mood, stress responses, and fatigue by interacting with neurotransmitters and hormones like serotonin and cortisol. Probiotics can support this axis by improving gut health, reducing inflammation, and potentially alleviating stress and anxiety, which are common in athletes under intense physical demands. By supporting a balanced microbiome, probiotics may help improve both mental resilience and physical performance.
However, the effectiveness of probiotics in reducing gastrointestinal-induced inflammation and perceived fatigue in athletes remains uncertain. A review, that was published in 2024, looked to comprehensively analyze the data in this emerging and rapidly expanding field of study. Through the evaluation and consolidation of top-quality randomized controlled trials, the results of various studies were scrutinized to uncover any correlations or trends regarding inflammation, probiotic intake, and athletic performance.
Different Types of Probiotics
Different types of probiotics offer unique benefits and vary in their resilience to the digestive environment, including stomach acidity. These include Yeast-Based Probiotics, Spore-Based Probiotics and Bacteria-Based Probiotics.
Here’s a breakdown of common probiotic types and their specific advantages:
Type | Key Strains | Survivability | Antibiotic Resistance | Common Uses | Stability |
Yeast-Based | Saccharomyces boulardii | High survivability in heat, stomach acid | Resistant to antibiotics | Diarrhea, gut health, inflammatory bowel disease | Heat-stable, no refrigeration needed |
Spore-Based | Bacillus coagulans, Bacillus subtilis | Spores protect them from harsh conditions | More resistant to antibiotics and harsh environments | Gut health, immune support, anti-inflammatory | Shelf-stable, no refrigeration needed |
Bacteria-Based | Lactobacillus, Bifidobacterium species | More sensitive to heat, stomach acid | Sensitive to antibiotics | Digestive health, immune support, mental and skin health | Some strains need refrigeration |
The Link Between Probiotics and Athletic Performance
The review analyzed 13 high-quality randomized controlled trials, assessing athletes and recreationally active individuals. The studies revealed promising results, with many showing improvements in endurance, GI symptoms, and stress levels. Notably:
Endurance Benefits: Probiotic supplementation improved time to exhaustion and aerobic capacity in some trials, however, there were NO significant enhancement shown in maximal oxygen uptake (VO2 max).
Reduced GI Symptoms: Athletes who took probiotics reported fewer symptoms like nausea and cramps, potentially enhancing GI comfort and improving cognitive strain during competitions like endurance events.
Inflammation and Recovery: Probiotics helped decrease levels of inflammatory markers such as TNF-α and IL-6. They also mitigated exercise-induced muscle damage indicators like creatine kinase (CK) and lactate, suggesting reduced muscle strain and faster recovery.
Important Probiotic Strains and Their Applications
Different probiotic strains provide specific benefits that can help improve various aspects, such as enhanced endurance performance, reduced anxiety and stress levels, decreased gastrointestinal symptoms, and lower incidence of upper respiratory tract infections (URTI).
The review highlighted multiple studies showing that probiotic supplementation can lead to improvements in lactate, creatine kinase (CK), and ammonia levels, indicating positive effects on reducing exercise-induced muscle stress and damage.
When purchasing a probiotic at the pharmacy or health store, keep an eye out for these specific probiotic strains:
Lactobacillus Plantarum - Shown to reduce ammonia and lactate, easing fatigue and muscle soreness.
Lactobacillus Acidophilus - Known for gut health support and immune enhancement.
Bifidobacterium Longum - May alleviate GI symptoms, beneficial for endurance athletes who often experience stomach discomfort.
Saccharomyces Boulardii - A yeast-based probiotic, effective for preventing traveler’s diarrhea and balancing gut flora after antibiotics.
Choosing the Right Probiotic For You
Determining the suitable probiotic for your needs can be a challenge. It all comes down to identifying the specific problem you want to address. Selecting the appropriate probiotic type and ensuring the correct dosage are crucial. Athletes should take into account the following factors when choosing a probiotic:
Dose
According to the conclusions drawn from this review paper, consuming a multi-strain probiotic with a minimum of 15 billion CFUs per day for a period of at least 28 days could potentially help alleviate both perceived and actual fatigue. However, certain studies in this review also found single strains to be effective in addressing other areas of health.
Training Intensity
For individuals undergoing intense training, consider incorporating strains such as L. Plantarum and L. Acidophilus into your routine, as they are known to promote gut health and reduce inflammation. A study mentioned in this review demonstrated a significant decrease in CK levels, pro- and anti-inflammatory cytokines, and oxidative stress (MPO) markers after evaluating inflammatory cytokines (TNF-α, IFN-γ, IL-2, IL-4, IL-6, IL-10) following the consumption of 3x 10(10) Lactiplantibacillus plantarum strain over a 4-week period.
GI Sensitivity
If you experience gastrointestinal issues, you may want to choose a multi-strain supplement containing B. Longum to help alleviate symptoms. A study mentioned in this review demonstrated that marathon runners who took a combination of 4 strains - Lactobacillus acidophilus CUL60, L.acidophilus CUL21, Bifidobacterium bifidum CUL20, and Bifidobacterium animalis subsp. Lactis CUL34 for 28 days experienced a decrease in the frequency and intensity of GI symptoms.
Form and Stability
Yeast-based probiotics like Saccharomyces boulardii and spore-based probiotics such as Bacillus coagulans don’t require refrigeration. Their stability allows them to survive harsh conditions, including stomach acid and higher temperatures, making them convenient options that maintain potency without refrigeration. These type of probiotics are ideal for travel or taking alongside meals.
Many bacteria-based probiotics, especially certain Lactobacillus and Bifidobacterium strains, are more delicate and often require refrigeration to maintain their potency. These strains are sensitive to heat and light, so refrigeration helps preserve their effectiveness. However, some bacteria-based probiotics can also be formulated to be shelf-stable, so it’s always best to check the label for storage instructions.
Tip: If you found it in the fridge at the health store or pharmacy, it belongs in the fridge!
Probiotic-Rich Foods
If purchasing probiotic supplements is not within your budget, athletes can incorporate natural probiotic sources into their diets instead of depending on supplements.
Yogurt: Choose plain, unsweetened varieties with live active cultures.
Kefir: A fermented milk drink rich in multiple strains of probiotics.
Sauerkraut and Kimchi: Fermented cabbage packed with beneficial bacteria.
Tempeh: A fermented soybean product, ideal for plant-based athletes.
Miso: A Japanese fermented soybean paste, adding flavor and probiotics to soups and sauces.
Limitations
Before you go rush out to go buy a probiotic. Consider the following: while the potential of probiotics in reducing GI distress, inflammation, and fatigue for athletes is promising, several limitations must be acknowledged. This review highlights a lack of standardization across studies, with varying probiotic strains, doses, and intervention durations. Different study designs and training conditions further complicate establishing a clear consensus on the most effective strains and dosages for athletic performance.
Additionally, probiotic effects can be strain-specific, meaning one type may benefit endurance athletes while another may not yield the same results. Limited research also addresses the long-term impacts of probiotic supplementation, making it challenging to recommend a universally effective probiotic approach for all athletes. Future studies are essential to pinpoint optimal strains, doses, and protocols to maximize benefits reliably across athletic populations.
Final Thoughts
Probiotics are becoming increasingly popular among athletes aiming to enhance gastrointestinal health, lower inflammation, and fight fatigue. When selecting a probiotic, prioritize strains that align with your particular training requirements.
In my opinion, probiotics can serve as a beneficial supplement worth considering, provided that you choose the right dosage and type to target the specific area of health or performance you aim to enhance. On the other hand, incorporating a greater variety of probiotic-rich foods into your diet is a safe and healthy approach to increasing your probiotic intake, while also ensuring you receive essential nutrients such as vitamins and minerals as an athlete.
If you're unsure which probiotic strain and dose best suit your needs, I’m here to help! Contact me at anniesathletes@gmail.com, and let’s find the ideal solution to support your athletic performance and health.
References
Kearns, R.P., Dooley, J.S.G., Matthews, M., & McNeilly, A.M. (2024). Do probiotics mitigate GI-induced inflammation and perceived fatigue in athletes? A systematic review. Journal of the International Society of Sports Nutrition, 21(1), 2388085. https://doi.org/10.1080/15502783.2024.2388085 
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