Gut Health & Gains: Why Fibre is Key for Muscle Building
- Daniela Radoman
- Mar 24
- 6 min read
When it comes to building muscle, getting enough protein in is usually one of the first things that come to mind.
And for sure - it’s important!
But there might be another key component to your diet that you may want to divert some attention to.
If you’re someone who’s looking to gain muscle, or even just maintain the muscle you already have, then you’re going to want to care about fibre.
Wait, wait, fibre?!?
Yes, fibre.
The fibre that’s usually recommended if you can’t go to the bathroom… or if your bathroom break results are a little “off.”
The fibre that’s really, really good at helping reduce the risk of plenty of health conditions like cancer, diabetes, and heart disease.
The fibre that’s touted as helping reduce appetite and food cravings.
Last week’s article was all about the benefits of fibre, so if you want to read all about it, then just click HERE.
Fibre is crucial for having a healthy digestive system. Your digestive tract is full of little microorganisms that use fibre as its primary food source, and having a happy and healthy gut microbiome is important as it influences everything from digestion to your immune system functioning.
The cool part? It seems as though your gut microbiome also talks to your muscles - it’s literally called “Gut-Muscle Crosstalk.”1
What is Gut-Muscle Crosstalk?
Gut-Muscle Crosstalk, or also called Gut-Muscle Axis (GMA), is a complex relationship between the microbes in your digestive tract and skeletal muscle, and it can influence muscle mass, function, metabolism, and overall health.2,3
Inversely, your muscles and what you do with them (i.e. exercise) can also affect the gut microbiome composition and functioning.
To put it simply, the microorganisms in your gut affect muscles in a few ways1:
Microbial metabolites - short-chain fatty acids (SCFAs), bile acids, tryptophan metabolites
These can affect energy metabolism, inflammation levels, muscle protein synthesis, and fat metabolism.
SCFAs play a role in cell regulation and growth, and they promote muscle glucose (aka energy) uptake, and improve insulin sensitivity.
These antioxidant and anti-inflammatory compounds help attenuate the effects of exercise-induced oxidative stress.
Immune system regulation
A healthy gut reduces systemic inflammation which can help prevent muscle loss and promotes recovery and healing.
Neuromuscular communication
Involvement of the central nervous system and neurotransmitters affects muscle coordination and fatigue levels.
Exercise performance and motivation can be influenced since dopamine and serotonin can be affected by certain microorganisms in the gut.
There’s been lots of research in this area in recent years, and there’s still lots left to be uncovered.
Let’s take a look at some interesting human trials and see what researchers found.
The Studies
Study number 1 that we’ll be looking at looked at fecal samples from 27 individuals with sarcopenia (low muscle mass and function) and compared them to 60 healthy individuals. What the researchers found was that there were noticeable differences in the microbiomes between the two groups.4
The ones with sarcopenia were found to have:
Less overall diversity of microbes in the gut
Less SCFA-producing bacteria, which help with lowering inflammation, and may contribute to muscle mass decline.
More pro-inflammatory types of microbes which interfere with protein synthesis.
Another study took 728 female twins, including 111 pairs where one twin was dealing with frailty and the other twin had normal functioning.5 The findings were pretty similar to the study above:
Compared to the healthy participants, those with frailty showed significantly less microbiome diversity.
One paper took 60 older, frail individuals and put them into two groups.6 One group received a placebo while the other received a daily prebiotic (which is a type of fibre - this group specifically took inulin and fructooligosaccharides (FOS)).
After 13 weeks, the group who took the prebiotic showed a significant increase in hand grip strength while reporting less exhaustion, which are two criteria when looking at frailty syndrome.
A larger study out of Taiwan looked at physical performance markers in 2680 older adults and compared them to their fibre intake.7
After controlling for other variables, adults with higher levels of fibre intake were found to have better performance test results than those with lower fibre intake.
Those performance tests include:
Hand grip strength
Gait speed
Six minute walk distance
Slower Timed Up & Go Test (TUG)
Summary performance score
One interesting quirk from this study is that low fibre intake was considered to be less than 19g/day for men and less than 21g/day for women. Usually, men are recommended to eat more fibre, so it’s interesting this study had a higher minimum threshold for what’s considered low for women instead of men. This could be simply due to taking an average from what the participants were already consuming, and it just so happened that the women in the study consumed more fibre to begin with compared to the men.
Key Takeaways
The health and strength of your microbiome reflect your overall well-being and fitness.8
A diverse microbiome indicates a well balanced and healthy system, while a lack of microbial diversity can contribute to inflammation and disease.9
Fibre is one of the key players in enhancing the diversity of your microbiome.
Not only does fibre feed and give energy to the microorganisms living in your GI tract, but it helps proliferate these microbes and helps them run efficiently, which leads to plenty of health benefits.
You don’t need to know how exactly fibre affects muscles to know that you should be getting enough of it in your diet. Just know and remember that it affects your gut microbiome which affects pretty much every other system in your body.
As mentioned in our last article, the current recommendations state that women should aim to get at least 25g of fibre per day, while men should aim for a minimum of 38g per day.10 (Click the link to also see some tips on how to get more fibre in your diet.)
So, while protein is important and deserving of attention in the fitness space, fibre deserves some of that attention too.
If you're solely focusing on protein but neglecting other nutrients your body needs, don’t be surprised if you see suboptimal results - both purely fitness-wise and overall health-wise.
So, remember your mom’s advice: eat your veggies!!!
About Us
Our goal at Delta Kinesiology is to help women reach their health and fitness goals, whether it be online, in the gym, or in-house! We specialise in conditions and injuries that women are more likely to experience, and we tailor the sessions using evidence-based principles and methods to help you reach your goals. Whether that be going about your day pain-free, building muscle, improving stamina, or feeling better about yourself, we are here to help.
Check out some of the ways we can help below!
References
Przewłócka, K., Folwarski, M., Kaźmierczak-Siedlecka, K., Skonieczna-Żydecka, K., & Kaczor, J. J. (2020). Gut-Muscle AxisExists and May Affect Skeletal Muscle Adaptation to Training. Nutrients, 12(5), 1451. https://doi.org/10.3390/nu12051451
Chew, W., Lim, Y. P., Lim, W. S., Chambers, E. S., Frost, G., Wong, S. H., & Ali, Y. (2023). Gut-muscle crosstalk. A perspective on influence of microbes on muscle function. Frontiers in medicine, 9, 1065365. https://doi.org/10.3389/fmed.2022.1065365
Lustgarten M. S. (2019). The Role of the Gut Microbiome on Skeletal Muscle Mass and Physical Function: 2019 Update. Frontiers in physiology, 10, 1435. https://doi.org/10.3389/fphys.2019.01435
Kang, L., Li, P., Wang, D., Wang, T., Hao, D., & Qu, X. (2021). Alterations in intestinal microbiota diversity, composition, and function in patients with sarcopenia. Scientific reports, 11(1), 4628. https://doi.org/10.1038/s41598-021-84031-0
Jackson, M. A., Jeffery, I. B., Beaumont, M., Bell, J. T., Clark, A. G., Ley, R. E., O'Toole, P. W., Spector, T. D., & Steves, C. J. (2016). Signatures of early frailty in the gut microbiota. Genome medicine, 8(1), 8. https://doi.org/10.1186/s13073-016-0262-7
Buigues, C., Fernández-Garrido, J., Pruimboom, L., Hoogland, A. J., Navarro-Martínez, R., Martínez-Martínez, M., Verdejo, Y., Mascarós, M. C., Peris, C., & Cauli, O. (2016). Effect of a Prebiotic Formulation on Frailty Syndrome: A Randomized, Double-Blind Clinical Trial. International journal of molecular sciences, 17(6), 932. https://doi.org/10.3390/ijms17060932
Wu, I. C., Chang, H. Y., Hsu, C. C., Chiu, Y. F., Yu, S. H., Tsai, Y. F., Shen, S. C., Kuo, K. N., Chen, C. Y., Liu, K., Lee, M. M., & Hsiung, C. A. (2013). Association between dietary fiber intake and physical performance in older adults: a nationwide study in Taiwan. PloS one, 8(11), e80209. https://doi.org/10.1371/journal.pone.0080209
Singh, R. K., Chang, H. W., Yan, D., Lee, K. M., Ucmak, D., Wong, K., Abrouk, M., Farahnik, B., Nakamura, M., Zhu, T. H., Bhutani, T., & Liao, W. (2017). Influence of diet on the gut microbiome and implications for human health. Journal of translational medicine, 15(1), 73. https://doi.org/10.1186/s12967-017-1175-y
Acevedo-Román, A., Pagán-Zayas, N., Velázquez-Rivera, L. I., Torres-Ventura, A. C., & Godoy-Vitorino, F. (2024). Insights into Gut Dysbiosis: Inflammatory Diseases, Obesity, and Restoration Approaches. International journal of molecular sciences, 25(17), 9715. https://doi.org/10.3390/ijms25179715
Canada, H. (2019, January 22). Government of Canada. Canada.ca. https://www.canada.ca/en/health-canada/services/nutrients/fibre.html#
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