New Study Suggests “Four’s a Charm, Five’s a Harm” for Coffee Intake and Bone Health in Older Women

December 15, 2025

ADELAIDE, Australia — For millions of women, the morning ritual of brewing a hot cup of coffee is non-negotiable. But a significant new study tracking nearly 10,000 older women over a decade suggests that while that morning cup is safe, turning it into an all-day habit could come at a cost to bone health.

Researchers from Flinders University have found that consuming more than five cups of coffee daily is linked to lower bone mineral density (BMD) in older women, potentially increasing the risk of osteoporosis. Conversely, the study found that daily tea drinkers might enjoy a modest protective benefit for their bone density.

The findings, published recently in the peer-reviewed journal Nutrients, add a crucial layer of nuance to the long-standing debate over caffeine’s impact on the skeleton.

The “Dose Makes the Poison”

The study, titled “Longitudinal Association of Coffee and Tea Consumption with Bone Mineral Density in Older Women,” analyzed data from the Study of Osteoporotic Fractures, a massive dataset involving women aged 65 and older. By using repeated assessments of beverage intake and advanced imaging to track bone density over ten years, the researchers offered a clearer picture than previous snapshots.

The results paint a picture of moderation. Women who drank two to three cups of coffee daily showed no significant loss in bone density compared to non-drinkers. However, the tipping point appeared to be at high consumption levels.

“Overall, moderate coffee consumption… did not appear to harm bone health,” said Adjunct Associate Professor Enwu Liu, a co-author of the study from the College of Medicine and Public Health at Flinders University. “However, drinking more than five cups daily was linked to lower BMD, suggesting that excessive intake may be detrimental.”

Tea: The Unexpected Ally

While heavy coffee consumption raised red flags, tea emerged as a potential ally in the fight against bone loss. The study observed that tea drinkers maintained slightly higher total hip bone mineral density compared to those who abstained.

Ryan Yan Liu, a co-author of the paper, suggests the difference lies in the chemical makeup of the beverages. “Tea contains compounds called catechins and flavonoids, which have been shown in laboratory studies to promote bone formation and slow bone breakdown,” he noted.

In contrast, caffeine—the primary stimulant in coffee—is known to interfere with calcium absorption. “Coffee’s caffeine content… has been shown to interfere with calcium absorption and bone metabolism,” Ryan Liu explained. However, he emphasized that these effects are often small and can be mitigated. “They can be offset by adding milk.”

A Public Health Priority

The implications of these findings are significant given the demographics of the aging population. Osteoporosis is a “silent disease” that causes bones to become weak and brittle. According to the International Osteoporosis Foundation, approximately one in three women over the age of 50 will experience an osteoporotic fracture. In the United States alone, the condition impacts over 10 million people, creating an annual economic burden estimated at $19 billion.

“Osteoporosis remains a serious public health issue,” Enwu Liu stated. “Even small improvements in bone density can translate into fewer fractures across large groups.”

For healthcare professionals, this data offers a specific, evidence-based counseling point: telling patients to “cut back” is vague, but advising a limit of “under five cups” is actionable.

Context and Conflicting Views

It is important to place these findings in the context of broader research. Previous meta-analyses have yielded conflicting results. For instance, a 2025 meta-analysis published in Frontiers in Nutrition found that moderate coffee consumption might actually be associated with a reduced risk of osteoporosis in some populations, likely due to antioxidant properties.

However, the Flinders study distinguishes itself by focusing specifically on older women—a group at highest risk due to post-menopausal estrogen loss—and by tracking them longitudinally for a decade. The distinction highlights that what is healthy for a general population may need adjustment for specific at-risk groups.

Dr. Sarah Bennett, a rheumatologist not involved in the study, noted that patients often panic about dietary restrictions unnecessarily. “We shouldn’t demonize coffee,” she said. “The takeaway here aligns with what we’ve seen in nutrition science for years: moderation is key. If you are an older woman with low bone density, swapping that fifth cup of coffee for a cup of green or black tea—or simply ensuring you get enough calcium—is a sensible, low-effort change.”

Practical Takeaways for Readers

So, should you pour your dark roast down the sink? The experts say no.

“Our results don’t mean you need to give up coffee or start drinking tea by the gallon,” Associate Professor Liu assured.

Actionable Tips based on the research:

• Stick to the ‘Safe Zone’: 2–3 cups of coffee per day appears neutral for bone health.

• Mind the Calcium: If you are a heavy coffee drinker, ensure you are getting adequate calcium. Adding milk or fortified plant-based milk to your coffee can help offset calcium loss.

• Consider Tea: Substituting one coffee break with a cup of tea might offer dual benefits: less caffeine and more bone-supporting flavonoids.

• Watch the Alcohol: The study found that women with higher lifetime alcohol consumption experienced more negative effects from heavy coffee drinking.

“While calcium and vitamin D remain cornerstones of bone health, what’s in your cup could play a role too,” Liu concluded. “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.”

Medical Disclaimer

Medical Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with qualified healthcare professionals before making any health-related decisions or changes to your treatment plan. The information presented here is based on current research and expert opinions, which may evolve as new evidence emerges.

References

1. Primary Study: Liu, R.Y., & Liu, E. (2025). “Longitudinal Association of Coffee and Tea Consumption with Bone Mineral Density in Older Women: A 10-Year Repeated-Measures Analysis in the Study of Osteoporotic Fractures.” Nutrients, 17(23). DOI: 10.3390/nu17233660.