Keeping your bones strong is important for your mobility, independence and quality of life throughout your life.
When you think about bone health, you may immediately think about calcium and drinking milk.
Calcium is certainly important — but there is another fascinating area of research that you may not have considered: the relationship between your gut and your bones.
This relationship is sometimes called the gut–bone axis.
Your gut microbiome, the food you eat and the compounds produced by your gut microorganisms may all interact with processes involved in bone formation and bone breakdown.
The research is still developing, but it gives us another reason to think about gut health as part of an overall approach to lifelong bone health.
What Is the Gut–Bone Axis?
Your bones are constantly being remodelled.
Specialised cells break down old bone, while other cells build new bone. This process is influenced by hormones, nutrients, physical activity, immune function and many other factors.
Researchers now know that the gut microbiome can interact with some of these pathways.
Gut microorganisms can ferment certain types of dietary fibre and produce compounds called short-chain fatty acids (SCFAs).
These compounds may influence:
- Immune regulation
- Inflammation
- Mineral metabolism
- Bone-forming cells
- Bone-resorbing cells
The gut microbiome may also influence how nutrients are absorbed and how hormones and other signalling pathways involved in bone metabolism behave.
This is why researchers are interested in the gut–bone axis. However, it is important to remember that much of the research is still mechanistic or observational, so we can’t say that having a particular gut microbiome will automatically give you stronger bones.
What Is a Prebiotic?
You may have heard that prebiotics “feed the good bacteria in your gut”.
There is some truth to this, but the terminology is important.
A prebiotic is a substance that is selectively utilised by microorganisms and provides a health benefit.
Some dietary fibres have prebiotic effects, but not all dietary fibre is technically a prebiotic.
Examples of foods containing fibres that can interact with your gut microorganisms include:
- Oats
- Wholegrains
- Lentils
- Chickpeas
- Beans
- Onions
- Garlic
- Some fruits and vegetables
When certain fibres are fermented by gut microorganisms, compounds such as short-chain fatty acids are produced.
These compounds are one of the reasons researchers are investigating whether diet and the microbiome may influence bone metabolism.
Can Prebiotic Fibre Help Your Body Absorb Calcium?
This is one of the most interesting findings in gut–bone research.
Some specific prebiotic fibres, particularly inulin-type fructans and fructooligosaccharides, have been shown in some human studies to increase calcium absorption.
For example, a randomised controlled trial in adolescents found that supplementation with a combination of short- and long-chain inulin-type fructans increased calcium absorption and was associated with greater increases in whole-body bone mineral content and bone mineral density over one year.
However, results have not been consistent across all studies.
A study in postmenopausal women found no significant overall increase in calcium absorption with short-chain fructooligosaccharides, while another small study using an oligofructose-enriched inulin preparation found increased calcium and magnesium absorption in postmenopausal women.
This means it would be too strong to say that eating more fibre automatically strengthens your bones by increasing calcium absorption.
A better message is:
Some specific prebiotic fibres may improve calcium absorption, and the gut–bone axis is an exciting area of research.
Most Calcium Is Absorbed in Your Small Intestine
There is another important correction to the way this topic is sometimes described online.
The majority of dietary calcium absorption occurs in the small intestine.
However, when certain fibres are fermented by gut microorganisms in the large intestine, the resulting changes in the gut environment may allow additional calcium absorption there.
This is one proposed mechanism behind the gut–bone connection.
So rather than saying that “most calcium is absorbed in the large intestine”, it is more accurate to say that the large intestine may contribute to calcium absorption under certain circumstances, particularly when fermentation increases calcium solubility and availability.
Fibre and Bone Health: What Does the Research Show?
We don’t yet have enough evidence to say that simply eating more fibre will prevent osteoporosis.
However, a 2026 systematic review and meta-analysis of observational studies found that higher dietary fibre intake was associated with higher bone mineral density in adults. Because these were mainly observational studies, the findings show an association rather than proving that fibre itself caused stronger bones. The authors also called for larger prospective studies.
There is another reason a fibre-rich diet may be helpful.
People who eat plenty of fibre-rich plant foods are often also consuming more potassium, magnesium, vitamin K, polyphenols and other nutrients and compounds that contribute to overall health.
So the benefit may not come from fibre alone.
It may be part of a broader healthy dietary pattern.
What About Probiotics?
This is another area of rapidly developing research.
Remember that a probiotic is a live microorganism that, when consumed in an adequate amount, provides a health benefit.
Probiotic effects are also strain-specific. You therefore cannot assume that every probiotic supplement or fermented food will have the same effect on your bones.
Interestingly, a 2026 systematic review and meta-analysis of randomised controlled trials found that probiotic supplementation was associated with modest improvements in lumbar spine bone mineral density, and to a lesser extent hip bone mineral density. Most of the trials involved postmenopausal women. However, the studies varied considerably and the researchers noted substantial heterogeneity.
This is promising, but probiotics should currently be viewed as an emerging area of research rather than an established bone-health treatment.
What About Fermented Foods?
Fermented foods can be included as part of a varied diet.
Depending on how they are made and processed, some may contain live microorganisms.
Examples include:
- Yoghurt containing live cultures
- Kefir
- Kimchi
- Sauerkraut
- Tempeh
- Natto
However, fermented foods are not automatically probiotic foods.
The microorganisms present can vary between products, and a health benefit demonstrated for one specific probiotic strain cannot automatically be applied to all fermented foods.
So rather than worrying about eating a certain number of probiotic foods every day, simply include fermented foods that you enjoy as part of a varied diet.
Variety Is Still Important
Different plant foods provide different types of fibre and other compounds that can interact with your gut microorganisms.
This is why eating a variety of plant foods is a useful habit.
Try including:
Wholegrains
- Oats
- Wholegrain bread
- Brown rice
- Quinoa
- Wholegrain pasta
Fruit
- Berries
- Apples
- Kiwi fruit
- Bananas
- Oranges
- Stone fruit
Vegetables
Aim for a mixture of colours and types across the week.
Legumes
- Lentils
- Chickpeas
- Kidney beans
- Other beans and peas
Nuts and Seeds
- Almonds
- Walnuts
- Chia seeds
- Pumpkin seeds
- Flaxseeds
You don’t need to reach a particular number of plant foods to have a healthy gut.
A useful goal is simply to increase variety over time.
How Much Fibre Do You Need?
For Australian adults, the Nutrient Reference Values recommend an adequate intake of:
- 25 g of fibre per day for adult women
- 30 g of fibre per day for adult men
Some people may need more depending on their individual dietary needs.
The easiest way to increase your fibre intake is not to rely on a fibre supplement. Instead, build meals around a variety of wholegrain, fruit, vegetable, legume, nut and seed foods.
If you currently eat very little fibre, increase it gradually and make sure you drink enough fluid.
But Don’t Forget the Big Players in Bone Health
The gut–bone axis is fascinating, but we shouldn’t let it distract us from the factors we already know are important for bone health.
Calcium
Calcium is essential for maintaining the structure and strength of your bones.
Australian recommendations vary by age and sex, but for many adults the RDI is 1,000 mg per day, increasing to 1,300 mg per day for women over 50 and adults over 70.
Good food sources include:
- Milk
- Yoghurt
- Cheese
- Calcium-fortified soy milk
- Calcium-set tofu
- Canned sardines with bones
- Canned salmon with bones
- Some leafy green vegetables
Vitamin D
Vitamin D helps your body absorb and use calcium and is important for bone health.
Sun exposure is an important source of vitamin D in Australia, while some foods also contribute.
Food sources include:
- Oily fish
- Eggs
- Some fortified foods
Whether you need vitamin D supplementation depends on your individual circumstances.
Protein
Protein provides the building blocks your body needs to maintain muscles and other tissues, including bone tissue.
Good sources include:
- Fish
- Lean meat
- Poultry
- Eggs
- Dairy foods
- Tofu
- Legumes
- Nuts and seeds
Physical Activity
Your bones respond to mechanical loading.
Weight-bearing and resistance exercise are therefore important components of maintaining bone strength alongside adequate nutrition.
This is particularly important throughout adolescence and young adulthood when peak bone mass is being established, and later in life when preserving bone and muscle becomes increasingly important.
Building Strong Bones Starts Early
Your teenage years are an important period for developing bone mass.
The skeleton accumulates a large amount of bone mineral during growth, so adolescence is an important opportunity to establish a strong foundation for later life.
This doesn’t mean teenagers need special “bone supplements”.
Instead, focus on the basics:
Enough food + adequate calcium + vitamin D + protein + varied plant foods + regular weight-bearing activity.
These foundations continue to matter throughout adulthood.
Your Gut Is One Piece of the Puzzle
It can be tempting to turn the gut–bone axis into another nutrition trend and start searching for the perfect probiotic, prebiotic powder or microbiome supplement.
You don’t need to.
The research is exciting because it suggests that your gut microorganisms may communicate with your bones through metabolic, immune and hormonal pathways. However, we are still learning exactly how important these pathways are in humans and which interventions will produce meaningful long-term improvements in bone health.
For now, a varied diet is a practical way to support both your gut and your bones.
What Could a Gut- and Bone-Friendly Day Look Like?
Breakfast
- Rolled oats
- Milk or calcium-fortified soy milk
- Berries
- Chia seeds
Lunch
- Wholegrain wrap
- Chicken, salmon, tofu or chickpeas
- Spinach
- Tomato
- Avocado
- Extra virgin olive oil
Snack
- Yoghurt with live cultures
- Fruit
- Almonds
Dinner
- Salmon, tofu or lean meat
- Quinoa or brown rice
- Broccoli
- Roasted vegetables
- Lentils or beans
This type of day provides fibre, protein, calcium, magnesium and a range of plant compounds while supporting an overall nutritious dietary pattern.
Take Home Message
Your gut and your bones may seem completely unrelated, but research suggests they are connected through what is known as the gut–bone axis.
Certain prebiotic fibres can influence calcium absorption under some circumstances, and emerging research suggests that gut microbiome-targeted interventions, including specific probiotics, may influence bone mineral density. However, the evidence is still developing and these approaches should not replace the established foundations of bone health.
The best place to start is much simpler:
Eat enough calcium-rich foods. Include adequate protein. Get enough vitamin D. Eat a variety of fibre-rich plant foods. Include regular weight-bearing and resistance exercise.
You don’t need to create a perfect gut microbiome to build strong bones.
A varied, balanced eating pattern can support both your gut and your skeleton throughout life.
How Feed Your Future Dietetics Can Help
Bone health nutrition can become confusing when you’re told to focus on calcium one day and the microbiome the next.
At Feed Your Future Dietetics, I can help you translate the evidence into practical nutrition strategies that fit your lifestyle, preferences and nutritional needs.
Whether you’re looking to improve your calcium intake, increase dietary fibre, support gut health or build a balanced eating pattern that supports healthy ageing, nutrition can be personalised without unnecessary restriction.
With over 10 years of experience supporting Australians with their nutrition and health goals, Feed Your Future Dietetics provides individualised dietetic support Australia-wide via Telehealth using Zoom or Microsoft Teams.
To learn more or book an appointment:
ashleigh@feedyourfuturedietetics.com
References
- Zaiss MM, Jones RM, Schett G, Pacifici R. The gut-bone axis: how bacterial metabolites bridge the distance. Journal of Clinical Investigation. 2019;129(8):3018–3028.
- Chen YC, Greenbaum J, Shen H, Deng HW. Association Between Gut Microbiota and Bone Health: Potential Mechanisms and Prospective. Journal of Clinical Endocrinology & Metabolism. 2017;102(10):3635–3646.
- Whisner CM, Castillo LF. Prebiotics, Bone and Mineral Metabolism. Calcified Tissue International. 2018;102(4):443–479.
- Pang Y, Chen Z, Ju Y, et al. Association between dietary fiber intake and bone mineral density: a systematic review and meta-analysis of observational studies. European Journal of Nutrition. 2026;65(2).
- Hidayat K, Zhu Y, Rizzoli R, et al. Probiotic Supplementation and Bone Health Parameters in Adults: A Systematic Review and Meta-Analysis. Osteoporosis International. 2026;37(1):41–56.
- Cantón-Cordeiro T, Shimochi S, Nakamura M, Puigbò P. The Gut-Bone Axis: A Systematic Review on the Potential Intervention Pathways for Bone Health. Life. 2026;16(6):909.
- Zhang T, et al. The Gut-Bone Axis and Skeletal Health: Regulatory Mechanisms and Therapeutic Applications of Plant-Derived Bioactive Compounds. Biomolecules. 2026;16(6):912.
- Tahiri M, Tressol JC, Arnaud J, et al. Effect of short-chain fructooligosaccharides on intestinal calcium absorption and calcium status in postmenopausal women: a stable-isotope study. American Journal of Clinical Nutrition. 2003;77(2):449–457.
- Holloway L, Moynihan S, Abrams SA, et al. Effects of oligofructose-enriched inulin on intestinal absorption of calcium and magnesium and bone turnover markers in postmenopausal women. British Journal of Nutrition. 2007;97(2):365–372.
- Abrams SA, Griffin IJ, Hawthorne KM, et al. A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents. American Journal of Clinical Nutrition. 2005.
- Australian Government. Nutrient Reference Values for Australia and New Zealand – Dietary Fibre.
- Australian Government. Nutrient Reference Values for Australia and New Zealand – Calcium.
