Yogurt is a fermented dairy product with high nutritional value and multiple health benefits; however, its impact on bone health remains unclear.
Study
The researchers of the current study performed a systematic review of 12 observational studies examining the effect of yogurt, rather than just milk or dairy products, on bone health in adults with and without osteoporosis. Bone health was based on bone mineral density (BMD), fracture risk, and markers of bone turnover. The review could not establish causality because no randomized controlled trials were identified.
Reasons for study rejection included incorrect population attributes, fermented products, or additives, including prebiotics and postbiotics. Notably, the use of S. thermophilus and L. bulgaricus as prebiotics also led to their removal from the study. Interventions with yoghurt enriched with additional probiotics, vitamin D, or other bioactive compounds were also excluded to ensure only traditional yoghurt was assessed.
Other exclusion criteria included studies that did not provide pre-defined outcomes, did not have a control group, as well as those with a short follow-up period of six months or less. Studies that did not accurately detect changes in BMD or fracture risk, as well as those that lacked specific bone health end points, were also excluded from the final analysis.
Results
Two of the 12 studies included in the current review suggested a small protective effect of high yogurt consumption against osteoporosis and a positive effect on BMD; however, no protection against fracture was observed. Moreover, the meta-analysis of six cohort studies did not report that yogurt was associated with a reduced risk of hip fracture or increased BMD. Although the pooled analysis showed a statistically significant effect on BMD, the effect size was extremely small (SMD = 0.009) and considered clinically negligible.
None of the reviewed studies quantified bacterial counts of the yogurt used or their viability, both of which are crucial metrics that reflect the functional properties. Another factor that may influence outcomes is that none of the included studies measured baseline vitamin D and calcium status of the study participants, which further introduces biological heterogeneity into the analysis.
Several studies have established that the numerous individual dietary constituents present within yogurt confer notable health benefits. Notably, the fermentation process that produces yogurt, the increased bioavailability of these nutrients, and their effects on the gut microbiome may confer additional health benefits. The review emphasized that yoghurt contains vitamin K2, which plays a key role in bone mineralization, and that variation in starter cultures and fat content may affect nutrient composition. Alterations of the gut microbiota and production of short-chain fatty acids also suggest potential gut-bone axis effects, though they remain difficult to quantify.
The studies limited the characterization of yoghurt; details such as fat content, fortification, and whether probiotic strains beyond the traditional starter were included were rarely reported. ~This lack of product characterization further contradicts the findings.
Conclusion
The current review suggests that yogurt does not directly reduce fracture risk or increase BMD in adults. Nevertheless, well-designed randomized controlled trials that accurately characterize the ingredients, bioactive components, and probiotic strains of yogurt should be conducted to confirm the association between this dairy product and bone health.
Until then, yoghurt may still be valuable as part of a balanced diet, but its effectiveness as a primary strategy for bone health remains unsubstantiated.
Source:
https://www.news-medical.net/news/20251003/Does-yogurt-strengthen-your-bones.aspx