Your Bones’ Best Buddy: Bacteria in Your Gut

Whether you are male or female, young or old, it’s wise to keep tabs on the health of your bones. About half of all adults age 50 or older suffer from osteoporosis (weak bones) or its precursor, osteopenia (low bone density). These days another worrisome trend is emerging: More and more young people are developing osteoporosis.


Unhealthy Lifestyle Foreshadows Osteoporosis

Young adults develop osteoporosis for many reasons, but the most likely cause is poor lifestyle choices like sedentary behavior and nutrient-deficient diets. Almost half of our bone mass develops during adolescence, making young people especially vulnerable to the nutritional deficiencies linked with osteoporosis.


Inflammation Originates in Your Gut

Traditional wisdom connects strong bones with calcium-rich diets, but recent research has identified a new player on the bone-building team - the bacteria residing in your gut. A healthy gut is populated by many different bacterial species. Ideally, most are “commensal,” meaning they help to keep you well. However, this ratio can easily be disrupted. When your gut bacteria get out of whack, higher levels of inflammation, which has been linked with virtually every chronic disease, are one result


Inflammation is an active player in the bone-building process. Our bodies are constantly breaking down old bone (which is triggered by inflammation) and building new bone to replace it. To oversimplify, when bone building lags behind bone removal, osteoporosis develops.


Junk Food Fosters Inflammation

We’ve long known that certain foods (as a group ultra-processed foods are the major offender) trigger inflammation. Now we are gaining insight into the biological underpinnings of how this works: these manufactured foods encourage the growth of bacteria that foster inflammation. Fortunately, there’s an opposite side to that coin: Diets rich in nutritious plant foods support the growth of bacteria that help to keep inflammation in check.

Unfortunately, young people have notoriously bad eating habits. Research shows that children and teen-agers - a period during which it’s vital to consume an adequate supply of bone-building nutrients - obtain two-thirds of their calories from high-calorie, nutrient-deficient, ultra-processed  foods. Numerous studies have linked a diet high in these manufactured edibles - which is, unfortunately, not limited to young people - with poor bone health.


Consider that people who eat plenty of ultra- processed foods are also likely to drink copious amounts of soda, ramping up the risk for osteoporosis. Soft drinks are high in phosphates, which rob bones of calcium. Soda has also been shown to promote inflammation, creating something of a viscous, bone-destroying circle.


Bacteria Support Bone Health

When it comes to building strong bones. friendly microbes perform numerous functions, in addition to tamping down inflammation. For instance, certain species, like those belonging to the lactobacillus and bifidobacteria families, help the body to absorb bone-building minerals like calcium, magnesium, and phosphorus.


It’s More Than Nutrients

It takes a village of nutrients to build strong bones, but traditionally two have shared the starring role: calcium and vitamin D. Your body can’t absorb the calcium it needs without the so-called sunshine vitamin. However, recent research suggests that obtaining adequate levels of vitamin D through sunlight or supplements may not be enough to support strong bones. Your friendly microbes need to be part of the team.


Sources like certain foods and sunlight provide what is known as “precursor” vitamin D. This is the form that is measured by standard blood tests. However, before your body can tap into its benefits, precursor vitamin D needs to be transformed into the active version, a process requiring the help of certain bacteria residing in your gut. This missing step may account for some of the discrepancies in studies investigating vitamin D’s contribution to bone health.


Other micronutrients, notably vitamin K, magnesium, zinc, iron, phosphorus and selenium, also support strong bones. Emerging research suggests their efficacy may be linked with gut bacterial composition. Apparently, gut bacteria have a synergistic relationship with the nutrients you provide in ways that support the bone-building process.


Consider, for instance, that when some species of “good guy” bacteria digest certain carbohydrates provided by plant foods (fiber is the major one) they a generate compounds like short-chain fatty acids. These substances help to regulate the bone-building process. Laboratory studies have shown that their provision can significantly improve osteoporosis.


Scientists have just begun to chart the role that friendly microbes play in building strong bones. Some of the connections are still speculative, but we do have enough basic information to recommend a definitive strategy.  Over the long term, avoiding processed foods and consuming a nutritious diet built around wide variety of whole foods is your best bet for building and maintaining strong bones.


Dietary approaches like the Mediterranean diet (primarily plant-based foods like fruits, vegetables, whole grains and legumes plus healthy fats mainly from fish and olive oil) have been shown to reduce inflammation and promote bone health. We now know that these dietary patterns are beneficial in part because they boost the ratios of friendly gut bacteria. This sets the stage for a kind of biological win-win. The nutrients provided by a healthy diet interact synergistically with beneficial bacteria - each enhancing the other’s ability to support good health, including building strong bones.


Judith Finlayson is a journalist and bestselling author with a longstanding interest in health and nutrition. Her most recent book, You Are What Your Grandparents Ate:  What You Need to Know About Nutrition, Experience, Epigenetics, and the Origins of Chronic Disease, was published in 2019. It has been translated into 7 foreign-language editions, including French, German, Spahis and Japanese.. Visit her at

Selected Resources:

Bolte, L. et al. Long-term dietary patterns are associated with pro-inflammatory and anti-inflammatory features of the gut microbiome. Gut 2021

De Sire, A. et al. Role of Dietary Supplements and Probiotics in Modulating Microbiota and Bone Health: The Gut-Bone Axis. Cells 2022

Ding, K. et al. Gut Microbiome and Osteoporosis. Aging and Disease 2020

Thomas, R. . et al. Vitamin D Metabolites and the Gut Microbiome in Older Men. Nature Communications 2020.   

Zaretsky, J. et al. Ultra-processed food targets bone quality via endochondral ossification. Bone Research 2021.

1/25/2023 5:00:00 AM
Judith Finlayson
Written by Judith Finlayson
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.
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