A new study by researchers at Flinders University shows that drinking tea and coffee may have different effects on bone health in older women. According to ScienceDaily, the study's findings showed that tea consumption was associated with slightly higher bone density, while drinking more than five cups of coffee a day was associated with lower bone density.
In this study, the status of nearly 10,000 women aged 65 and over was examined over a 10-year period. Using data from the "Osteoporotic Fractures Study," researchers recorded participants' coffee and tea consumption at different periods and measured their bone mineral density in the hip and upper femur, two areas where bone density is closely linked to fracture risk.
Results showed that bone mineral density in the hip of women who drank tea was slightly higher compared with those who did not consume tea; this small difference was statistically significant.
Eno Liu, from the School of Medicine and Public Health at Flinders University, said that even a small increase in bone density in large populations could mean a reduction in the number of fractures.
For coffee, the results were different. Moderate consumption, about two to three cups a day, was not associated with harm to bone health, but women who drank more than five cups of coffee daily had lower bone density. There was also a stronger negative association between coffee consumption and bone density in women who had consumed more alcohol over their lifetimes. In contrast, the positive association of tea with bone density was more evident in women with higher obesity.
Ryan Liu, one of the study's authors, said that compounds called "catechins," abundant in tea, may promote bone formation and slow bone tissue breakdown. Conversely, laboratory studies have shown that the caffeine in coffee can interfere with calcium absorption and bone metabolism, although these effects are small and adding milk to coffee can partly offset this effect.
Researchers emphasized that the observed differences in bone density were limited and that moderate coffee consumption was not deemed harmful to bone health, but consuming more than five cups a day, especially in women who consume alcohol, was associated with lower bone density.
About one-third of women over 50 worldwide have osteoporosis, which is the cause of millions of fractures each year.