Two cups of coffee brewing, the beverage whose intake this study tracked against bone density over ten years
Chevanon Photography
Illustrative: generic coffee cups, not a photograph of the study, its participants, or any specific quantity of coffee.
Ten Years of Bone Scans on 10,000 Women Found the Line Where Coffee Stops Being Neutral
I keep seeing headlines that turn one line of a study into a verdict on your morning coffee, so when a real ten year cohort actually drew a line, I wanted to see exactly where it sat and how far the evidence really carries. Flinders University researchers tracked coffee and tea drinking against hip bone scans in nearly ten thousand women over sixty five for a decade, and the line they found is more specific, and less alarming, than any headline about it has been so far.
- Researchers used the Study of Osteoporotic Fractures to track coffee and tea intake against hip and femoral neck bone density in almost 10,000 women aged 65 and older, with repeated scans and repeated habit checks over 10 years.
- Tea drinkers had slightly higher hip bone density. Two to three cups of coffee a day showed no association with harm. More than five cups a day tracked with lower bone density.
- The coffee association was worse in women who also drank more alcohol over their lifetime. The tea benefit was stronger in women with obesity. Almost nobody covering this study mentioned either interaction.
- This is not new research. The paper was published in December 2025, and this is a republication nine months later. The study's own co author says the results are not a reason to change your habits.
No association at two to three cups a day
The association with lower hip bone density only appeared above five cups a day, and was worse in women who also drank more alcohol.
Slightly higher hip bone density
A small, statistically real association, stronger in women with obesity than in women at a lower weight.
Both associations are real in this cohort and both are small. Neither is a reason to change your habits on its own.
What ten years of bone scans actually tracked
The data comes from the Study of Osteoporotic Fractures, a long running research effort that has followed thousands of older American women for decades. For this analysis, researchers pulled bone mineral density scans at the hip and femoral neck from close to ten thousand women aged 65 and older, and matched them against how much coffee and tea each woman reported drinking, with both measurements repeated over ten years rather than taken once. That repeated design is what let the researchers see a pattern instead of a single snapshot. The Study of Osteoporotic Fractures is funded by the National Institute on Aging and the National Institute of Arthritis and Musculoskeletal and Skin Diseases, both part of the National Institutes of Health, and no coffee, tea, or beverage company funding was identified anywhere in the analysis.
Two beverages, opposite directions, both small
Tea drinkers in the cohort had slightly higher total hip bone density than non tea drinkers, a small difference but a statistically real one. The researchers point to catechins, plant compounds concentrated in tea, which in laboratory research appear to encourage bone formation and slow bone breakdown. Coffee told a different story, and only past a certain point. Women who drank two to three cups a day showed no association with lower bone density at all. The association only appeared above five cups a day, where it tracked with measurably lower bone density. The proposed mechanism is caffeine interfering with how the body absorbs calcium and manages bone turnover, an effect the researchers describe as small, and one they note can be partly offset by adding milk to your coffee.
The interaction almost nobody is writing about
Two details in this study are more interesting than the headline threshold, and neither has been showing up in coverage of it. The negative coffee association was stronger in women who also had higher lifetime alcohol intake, meaning the combination of heavy coffee and more drinking looked worse for bone density than either habit tracked with on its own. The tea benefit ran the other way: it was more pronounced in women with obesity than in women at a lower weight. Neither interaction proves one habit is causing the other to matter more, but both point toward the same idea, that these small beverage effects do not sit the same way across every woman, and a single population average hides real variation underneath it.
these small beverage effects do not sit the same way across every woman, and a single population average hides real variation underneath it
Honest caveat
This is not breaking news, and the dateline on the coverage is misleading. The underlying paper was published in the journal Nutrients in December 2025, and ScienceDaily itself already covered this exact study once before, in December 2025, under a different headline. What republished this week is a second pass at the same ten year old dataset and the same December 2025 paper, not a new finding. Beyond the timing, this is an observational study. It cannot prove that heavy coffee weakens bones or that tea strengthens them, because women who drink more than five cups of coffee a day likely differ from lighter drinkers in other ways the analysis cannot fully separate out, and reverse causation is also possible. The cohort is women aged 65 and older only, so nothing here transfers to men or to younger women. Coffee and tea intake were self reported, not measured. The actual outcome that matters to most people, whether someone breaks a bone, was not measured here at all. This study measured bone mineral density, a related but different thing. The exact size of these effects, in real bone density units, was not made available in the coverage this article draws from, so no such number appears in this piece. The catechin and caffeine mechanisms are both laboratory hypotheses, not something this particular study tested directly.
What this means for you
If you are a woman over 65, or getting close to it, the honest takeaway is narrower than a headline about it usually allows. Two to three cups of coffee a day showed no bone density association in this cohort, so there is no reason from this study to cut coffee out. More than five cups a day is where the association appeared, and it looked worse specifically in women who also drink more alcohol, which is a genuinely useful thing to know if that combination describes your week. If you already drink tea, this is a small, real point in its favor, and the effect looked stronger if you are also managing your weight, though that is one study's subgroup finding, not a guarantee. None of this replaces the two things every bone health conversation should still start with: calcium and vitamin D. The study's own co author is explicit that these results are not a reason to change your coffee or tea habits, and I think that is the right note to end on rather than talk you into or out of anything.
Primary sources
- Ryan Yan Liu, Enwu Liu. 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, 2025;17(23):3660.
- Too much coffee may weaken bones, study finds. ScienceDaily / Flinders University, September 2, 2026.
Common questions
Does this mean I should cut back on coffee to protect my bones?
Not based on this study alone. Two to three cups a day showed no association with lower bone density at all. The association only appeared above five cups a day, and it was stronger in women who also drank more alcohol. If your intake is in the moderate range, this particular study gives you no reason to change it.
Should I start drinking tea for my bones?
This study found a small, statistically real association between tea drinking and slightly higher hip bone density, stronger in women with obesity. It is observational, so it cannot prove tea causes denser bones, and the effect size was not published in the coverage this article is based on. It is a reasonable point in tea's favor, not a reason to treat it as a treatment.
Is this new research?
No. The underlying study was published in the journal Nutrients in December 2025, and ScienceDaily had already covered it once before, in December 2025. The September 2026 coverage is a republication of the same ten year old dataset and the same paper, not a new finding, and this article treats it as a standing explainer rather than breaking news.
Stay Curious.
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