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

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.

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.

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.

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.