Do gut problems play a role in poor bone formation?
A disrupted gut microbiome can contribute to poor bone formation through inflammation, reduced calcium absorption and bone-resorbing cells. A practical takeaway: eat a fibre-rich diet and limit salt, as both support your gut bacteria and your bones.
Calcium, vitamin D and exercise are well-known factors in bone formation, but your gut also plays a direct role. Gut bacteria produce short-chain fatty acids, such as butyrate. These fatty acids stimulate cells that build bone while simultaneously inhibiting cells that break bone down. This mechanism has been demonstrated in animal research and is supported by limited clinical studies.
A disrupted bacterial landscape in the gut also has the opposite effect. When the gut wall becomes too permeable, bacterial waste products leak into the bloodstream. This causes a low-grade, smouldering inflammation that fuels the breakdown process in bone. This connection has been described in multiple reviews and is regarded as one of the central links in the gut-bone axis.
The gut also influences bone formation in a more direct way: a healthy microbiome improves the absorption of calcium from food. Absorbing more calcium means more building material for bone. In addition, gut bacteria produce vitamin K, a substance that helps manufacture bone proteins. The effect of this microbiome-produced vitamin K on bones has not yet been well studied in humans.
After menopause, oestrogen levels fall, and this accelerates bone breakdown. The gut microbiome appears to mediate this process through immune cells that activate bone-resorbing cells. This suggests that post-menopausal women may be particularly vulnerable to the consequences of a disrupted microbiome on bones.
Probiotics and prebiotics show promising signals in early research: they appear to be able to slow bone loss to some extent. However, results in humans are still too inconsistent for concrete recommendations. Eating a lot of salt has already been linked to lower bone density, partly because a high salt intake also negatively affects the composition of bacteria in the gut.
Based on multiple reviews and animal studies; few large randomised studies in humans. Causality is plausible but has not yet been clinically proven in all areas.