Save Your Muscles: Revitalize Your Gut

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You’ve been working out regularly and meeting your daily goal of X-thousand steps for years, yet somehow you’re not as fit as you used to be. Be aware that you are not alone. You need to know that unless you are in your twenties or younger your muscles are waning.

Simply stated, you are getting older. While aging takes a toll on your body in general, it is especially unkind to your muscles. Muscles peak around the age of 30, then slowly (at best) they start to shrink. By the time your 80th birthday rolls around, almost half of your youthful muscle mass is likely to be gone.

Muscle decline connected with aging is known as sarcopenia. A sedentary lifestyle is a major perpetrator — a compelling reminder of the “use it or lose it” dictum — but other factors like poor nutrition and inflammation are co-conspirators. Being overweight, smoking and over-imbibing in alcohol also raise the risk of developing sarcopenia.

Numerous studies have also associated sarcopenia with fetal development. Babies born with low birthweight, often because they were poorly nourished in the womb, tend to have low muscle mass throughout their lives. As adults, they need to work harder than most to keep their muscles strong.

Muscles control many of the activities you take for granted, like walking, carrying groceries and cooking meals. When they start to slip, it sets the stage for a cascade of negative effects. If getting through the day is challenging, it diminishes your quality of life. A downward spiral — reduced mobility, health conditions like arthritis and osteoporosis, falls and fractures  — may result.

Luckily, we’re getting a handle on how to delay the onset of muscle loss. Not surprisingly, studies on sarcopenia have focused on older people. However, an emerging theme of that research can benefit everyone who is keen to remain healthy as they age.

A flurry of recent studies have zeroed in on the relationship between gut microbiota (the collection of bacteria that reside in your esophagus, stomach and intestines) and vigorous muscles. Basically, it links the loss of muscle mass and strength with an unhealthy microbiota.

Beneficial and harmful bacteria live together in your gut. An unhealthy microbiota (known as “dysbiotic”) harbours too many “bad guys.” Studies suggest that older people who remain physically strong have healthy microbiotas, whereas those who are frail show varying degrees of gut dysbiosis.

Researchers now theorize that a busy communications corridor runs between your muscles and your gut. Described as the gut-muscle axis this two-lane highway delivers a steady stream of messages from your gut to muscles and vice-versa. This awareness is leading scientists to speculate about therapeutic interventions that could target your gut bacteria, supporting robust muscles as you age.

Based on what we know about the links between your muscles and your gut, here are some tips that can help to keep you strong and active well into old age.

A varied diet of nutritious foods supports vigorous muscles. We know from studying elderly people that gut bacteria become less diverse with age, as does their diet. As a group, older people are known to be poorly nourished and prone to eating the same thing every day. This approach, often described by the cliché “tea and toast,” scuttles bacterial diversity. Eating a varied diet of nutritious foods is the most effective way to build a rich microbiome.

The scarcity of plant foods is particularly impactful as components of plants, including fiber, support the growth of beneficial gut bacteria. “Good guy” bacteria convert substances in food into compounds like short-chain fatty acids (SCFAs.) Among their many benefits, SCFAs help your body absorb nutrients that keep your muscles robust.

An anti-inflammatory diet benefits muscle. Another benefit of SCFAs is that these compounds are well-known inflammation fighters. Chronic inflammation has been linked with sarcopenia; the condition is so common in older people that experts have coined the term “inflammaging.”

The good news is that certain dietary approaches, notably the Mediterranean Diet (primarily plant-based foods such as whole grains, fruits, vegetables, legumes and nuts, plus healthy fats obtained mainly from fish and olive oil) have been shown to benefit gut health and to reduce inflammation. Although the research is in the early stages, some studies indicate a link between a preponderance of friendly gut bacteria and robust muscle mass.

Balancing polyunsaturated fatty acids slows muscle loss. We’ve long known that people in North America eat too many ultra-processed foods. One problem with this dietary approach is that it provides an abundance of inflammatory omega-6 fatty acids and far fewer omega-3s which tamp down inflammation. Studies suggest that omega-3 fatty acid supplementation can slow down age-related muscle decline, particularly when this therapy goes hand in hand with reducing consumption of omega-6 fats.

Recent research suggests another potential muscle-building benefit of omega-3 fatty acids: they communicate with your microbiome, promoting the growth of certain types of friendly bacteria and encouraging microbial diversity.

Exercise strengthens muscles by supporting bacterial diversity. The link between physical exertion and strong muscles is well recognized and numerous studies have shown that exercise helps to prevent sarcopenia. Recent research is showing another avenue of influence: exercise boosts microbial diversity, increasing the production of  anti-inflammatory SCFAs. These alterations in gut bacteria may also improve nutrient absorption and the body’s natural detoxification systems in ways that have been associated with increased muscle mass.

These days significant numbers of older people are expanding what experts describe as their “healthspan,” the  period of life free from chronic disease. Nourishing your gut bacteria is one strategy for reaching that goal. It can help you to maintain your muscles, remaining physically strong and vital well into old age.

Selected Resources

Sayer, A. et al. The Developmental Origins of Sarcopenia. The Journals of Gerontology Series A; 2008

Ticinesi, a. et al. Gut Microbiota, Muscle Mass and Function in Aging: A Focus on Physical Frailty and Sarcopenia. Nutrients 2019.

Ticinesi, A, et al. Human Gut Microbiome: the Hypothesis of a Gut-Muscle Axis in the Elderly. Dtsh Z Sportmed 2018

Smith, G. et al. Fish oil-derived n-3 PUFA therapy increases muscle mass and function in healthy older adults. The American Journal of Clinical Nutrition 2015.

Judith Finlayson is the author of You Are What Your Grandparents Ate:  What You Need to Know About Nutrition, Experience, Epigenetics, and the Origins of Chronic Disease. Visit her at



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