A decade-long study has found that drinking more than five cups of coffee a day may have negative effects on bone health.
Research conducted by Flinders University in Australia and published in the journal Nutrients tracked nearly 10,000 older women over a 10-year period to examine how regular coffee and tea consumption affects bone mineral density (BMD), a key indicator in assessing osteoporosis risk.
The study noted that osteoporosis remains a major global health concern, affecting about one in three women aged 50 and above and leading to millions of fractures each year. Given the widespread consumption of coffee and tea worldwide, researchers sought to determine whether these daily habits have long-term effects on bone health.
“Coffee’s caffeine content, by contrast, has been shown in laboratory studies to interfere with calcium absorption and bone metabolism, though these effects are small and can be offset by adding milk,” said Ryan Liu of Flinders University.
Researchers analyzed data from the Study of Osteoporotic Fractures, tracking participants’ beverage consumption and repeatedly measuring BMD at the hip and femoral neck—areas closely associated with fracture risk in older adults.
Findings showed that women who regularly drank tea had slightly higher total hip bone mineral density compared to non-tea drinkers, with protective effects more pronounced among women with obesity.
Moderate coffee intake—around two to three cups per day—was not associated with harmful effects on bone health. However, those who consumed more than five cups daily showed lower bone density, suggesting potential long-term risks for heavy coffee drinkers.
The study also found that the relationship between beverage intake and bone health may be influenced by other lifestyle factors. For instance, women with higher lifetime alcohol consumption experienced more pronounced negative effects linked to heavy coffee intake.
“While moderate coffee drinking appears safe, very high consumption may not be ideal, especially for women who drink alcohol,” said Associate Professor Enwu Liu, one of the study’s lead researchers.
Researchers added that while caffeine may slightly interfere with calcium absorption and bone metabolism, these effects are generally minimal and can be mitigated by simple practices such as adding milk.
The team emphasized that moderation remains key to maintaining bone health.
“Our results don’t mean you need to give up coffee or start drinking tea by the gallon,” said Associate Professor Liu. “But they do suggest that moderate tea consumption could be one simple way to support bone health, and that very high coffee intake might not be ideal, especially for women who drink alcohol.”
“While calcium and vitamin D remain cornerstones of bone health, what’s in your cup could play a role too. For older women, enjoying a daily cup of tea may be more than a comforting ritual—it could be a small step toward stronger bones,” he added.
