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Probiotics for Muscle Mass and Body Composition

Written by Dr. Michael Ruscio, DC on August 19, 2024

Written by Dr. Michael Ruscio, DC on August 19, 2024 — Reviewed by Kellie Blake

Probiotics Can Help Improve Muscle Mass While Helping You Lose Weight

• Probiotics & Muscle Mass|
• Protein + Probiotics|
• The Importance of Skeletal Muscle|
• Probiotics for Muscle Recovery|
• The Gut-Muscle Connection|
• Probiotics Aren’t Just for the Gut|

It never fails to amaze me just how many ways probiotics can support our health and well-being inside and outside of the gut, including muscle mass and improving your body composition. This might seem surprising and even unlikely, but we actually have research that shows taking probiotics can improve your muscle growth alongside a healthy diet, exercise, and getting enough protein to build those muscles.

We’ll look at how probiotic supplementation is especially helpful for older adults looking to put on muscle mass and improve conditions like sarcopenia (a loss of skeletal muscle mass with age), which is critical to keep people moving and to prevent injury with aging.

We’ll also look at using probiotics to increase muscle mass in healthy men and to improve muscle recovery. Finally, we’ll touch on the gut-muscle connection and look at why and how probiotics impact muscle growth.

Can Probiotics Really Increase Muscle Mass?

Yes, probiotics can really help you put on muscle, alongside a healthy diet, regular physical activity, and adequate protein consumption (which might be more than you think).

Here’s a high-level overview of the best research we have on this.

A recent meta-analysis showed that overall, probiotics had a positive effect on muscle mass in adults [1]. Similarly, recent clinical trials have shown that:

• When combined with a high-protein diet, probiotics appeared to increase skeletal muscle, normalizing the musculature in many adults with COVID-related sarcopenia [2]. 
• A probiotic-enhanced supplement containing fatty acids and the amino acid leucine appeared to significantly improve lean mass and grip strength in elders with sarcopenia [3]. 
• Taking probiotics appeared to increase muscle mass in healthy men [4].

This is exciting because we can see two clear applications for probiotic supplementation to increase muscle strength. 

1. Supporting healthy adults to increase muscle mass and improve strength, which is important for healthy aging
2. Helping older adults reverse age-related conditions like sarcopenia, which many people assume is normal and unavoidable, but is treatable with the right exercise program, getting enough protein, and the right probiotic bacteria

From the research above, what we know of using probiotics for weight loss and maintaining your metabolic health, and the general health benefits of a well-balanced gut microbiome, we can also infer that probiotics would be beneficial for adults with obesity looking to decrease body fat and increase muscle mass. 

But it’s also clear from the research that taking probiotics on their own isn’t enough to increase skeletal muscle. You need the actual building blocks of our muscles, too, amino acids, which are usually consumed as protein.

Protein + Probiotics: A Winning Combo

Protein, and specifically amino acids, are the raw materials that actually build our muscles. Probiotics or not, there’s no getting around increasing your protein intake if you want to build skeletal muscle, especially for older adults. 

But adding probiotics may help your gut more easily break down the protein you eat into those individual amino acids, and increase absorption of those amino acids, improving muscle protein synthesis [1]. 

In this way, we can kind of think of protein as the star and probiotics as a supporting player in growing muscles and improving strength. Protein is great on its own, but adding probiotics (and improving the gut microbiota) helps it shine even brighter. 

A couple of other ways probiotics may support muscle growth include:

• Increasing bacteria that produce short-chain fatty acids via fermentation in the gut (like butyrate), which may have positive impacts on skeletal muscle. (Consuming prebiotics like inulin is another great way to boost short-chain fatty acids).
• Reducing the degradation of creatine, which helps metabolize energy and contract muscles.

The Importance of Skeletal Muscle for Older Adults

Now I want to talk a little more about the importance of maintaining skeletal muscle in older adults and how probiotics can have a significant impact on this goal. Let’s go back to the study on diet and probiotics in older adults impacted by COVID. 

A 2022 randomized controlled trial (RCT) tested the effects of diet and probiotics on sarcopenia in adults who recently recovered from COVID. The study randomized 200 older COVID survivors (aged 59–76) to eat a higher protein diet and take probiotics or no intervention for 2 months. They all did three 40-minute sessions of exercise per week.

After 2 months, the high-protein and multistrain-probiotics group achieved a significant increase in skeletal muscle compared to the no-intervention group. The number of patients in the protein–probiotics group with normal musculature went from 32 to 70; those in the non-intervention group didn’t change significantly [2].

This is a pretty great result. I also want to point out that this study used a multi-species probiotic (usually a combination of Lactobacillus and Bifidobacteria probiotic strains), which research has shown outperforms a single-species probiotic on average. 

That said, another 2022 RCT compared a supplement containing a single-strain probiotic to a placebo for its effects on lean mass, muscle performance, inflammatory markers, and amino acid profiles in older people with sarcopenia [3]. 

The study randomized 50 elderly people with sarcopenia to take the supplement (omega-3s, the amino acid leucine, and probiotic Lactobacillus paracasei) or a placebo for 8 weeks. They followed a diet that provided 1.5 g protein/kg of body weight per day and performed personalized physical activity on a regular basis. 

After 8 weeks, compared to the placebo group, the probiotics group significantly [3]:

• Gained lean mass 
• Reduced fall risk and improved physical performance and strength
• Lost abdominal fat
• Had a healthier amino acid profile
• Decreased inflammation
• Gained body mass but lost visceral fat (which means a net gain of muscle!)

So it would seem that whether you choose a single-species probiotic or multi-species, older adults will likely get some benefit from taking probiotics alongside protein and exercise to build muscle and strength. 

Probiotics for Muscle Recovery

So we know probiotics can support muscle gains, but what about muscle recovery post-exercise? Turns out probiotics can help there too. 

A recent meta-analysis found that, compared to placebos, probiotics generally appeared to enhance aerobic performance to a small degree, especially in men [5]. A systematic review found some research suggesting that adding single or multi-strain probiotics to athletes’ diets showed promise for helping them reduce fatigue and muscle pain [6].

One large RCT found that probiotics appeared to reduce muscle strength loss and biomarkers of muscle damage and inflammation, and accelerate recovery in healthy people [7]. Another RCT also found that healthy men who took probiotics recovered faster than those who didn’t [4]. Finally, an RCT showed that probiotics improved recovery and reduced damage in men and women up to eight days after running a half-marathon [8].

Probiotics may have had these positive effects on performance and recovery by [5]:

• Preventing leaky gut and enhancing intestinal barrier function to reduce inflammation
• Improving carbohydrate absorption
• Decreasing free radicals and inflammation (similar to antioxidants), improving muscle health 

More reasons to take your probiotics, whether you’re a high-performing athlete, a regular gym goer, or you just want to have fewer aches and pains every time you run around in the backyard with your kids. A quick note: this study also found that athletes may benefit from a higher CFU (colony forming units) count, so if you’re an athlete, you may want to look for a probiotic with 30 billion CFU or higher. 

The Gut-Muscle Connection

You might have heard of the gut-brain connection or the gut-thyroid connection, but have you heard of the gut-muscle connection? Yep, the gut-muscle axis is a real thing. Here’s what we know. 

Current evidence-based theories suggest that there may be a gut-muscle connection that plays a role in regulating metabolism and the types of bacteria that live in the gastrointestinal tract [9]. 

More diversity in gut bacteria seems to be better for health, and more physical activity and better cardiorespiratory fitness are associated with greater beneficial diversity in gut microbes [9]. Probiotics also help increase the diversity of beneficial microorganisms in the gut.

Additionally, good gut bugs can produce short-chain fatty acids (SCFAs). SCFAs like butyrate seem to reduce inflammation, support the immune system, and provide us and our muscles with energy [9, 10, 11]. This suggests a complementary cycle between the gut and muscles, where each supports the other in a continuous loop.

Basically, we know that exercise, cardiorespiratory fitness, and building muscle are good for you. We also know that having a diverse range of probiotics in the gut (like Lactobacillus acidophilus, Bifidobacterium longum, and many others) is also good for you. It turns out that both of these things can support each other, propelling your health in a positive upward spiral. Everybody (you, your gut microbiome, your muscles) wins. 

Probiotics Aren’t Just for the Gut

While probiotic bacteria mostly live in your gut, the effects of probiotics really are wide-reaching throughout your entire body—from the brain, to metabolic health, to building muscle mass. 

Whether you’re an older adult looking to maintain strength and prevent injury, a pro weightlifter looking to pack on muscle and improve athletic performance, or simply an average gym goer who wants to maximize their workouts, consider adding a good quality multi-species probiotic to your regimen to increase muscle mass and strength.

If you want to learn more about probiotics, improving your gut health, exercise habits, and fitness in the context of your overall health, check out my book Healthy Gut, Healthy You, or visit my YouTube channel.

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.