Association between varying fermentation levels of tea and bone health in a community-based population

INTRODUCTION: The association between teas with different fermentation levels and bone health remains unclear. We aimed to investigate the association between teas with different fermentation levels and bone health in a community-based population. METHODS: This is a cross-sectional study. Participants were recruited using a multistage probability sampling method in China between 2021 and 2023. At baseline, participants self-reported the type (unfermented green, semi-fermented oolong, fully-fermented black, and post-fermented dark) and frequency of tea consumption. Bone mineral density was measured using calcaneal ultrasonography. RESULTS: A total of 8,490 participants were included in the analysis, with a mean age of 51.5 years. The prevalence of osteopenia and osteoporosis was 2.8% and 18.6%, respectively. The average duration of tea consumption was 29.3 years. Compared to the non-tea group, the adjusted odds ratios (OR) for osteopenia/osteoporosis associated with regular intake (≥ 3 days per week) of green tea, oolong tea, black tea, and dark tea were 0.79 (95% CI: 0.67-0.93), 0.84 (95% CI: 0.73-0.97), 1.03 (95% CI: 0.86-1.25), and 0.98 (95% CI: 0.78-1.23), respectively. Linear associations were observed only between the frequency of green or oolong tea consumption and osteopenia/osteoporosis (P for trend < 0.05). Similar results were found regarding the level of fermentation and bone health (P for trend < 0.05). The associations between tea type, consumption frequency, and bone health remained robust in multiple sensitivity analyses. CONCLUSION: Tea fermentation level was significantly associated with bone health. Regular consumption of unfermented and semi-fermented teas was associated with lower odds of having osteopenia/osteoporosis.