We all reach for tea or coffee to kickstart the day, push through long work hours, or simply feel more alert. But could this everyday habit be quietly affecting bone health?
A new study published in Nutrients suggests it might; at least for older women. Tracking nearly 10,000 women aged 65 and above over a decade, researchers found that while tea was linked with better bone health, high coffee consumption was linked to lowered bone mineral density— a key marker that measures the levels of calcium and other minerals in the body used to assess osteoporosis and fracture risk.
The question is especially relevant as coffee consumption continues to rise globally and in India. While coffee and tea are among the most widely consumed beverages worldwide, India’s coffee intake has been steadily increasing alongside the growth of café culture and changing lifestyle preferences. India’s domestic coffee consumption has steadily risen from 84,000 tonnes in 2012 to 91,000 tonnes in 2023, with the country exporting $1.29 billion worth in FY 2023–24.
At the same time, osteoporosis remains a major public health concern, affecting roughly one in three women over the age of 50 and leading to millions of fractures each year.
Against this backdrop, understanding whether popular beverages like coffee and tea help or harm bone health is not just a matter of personal choice, but an important public health question.
What did the study find?
The study, conducted by researchers at Flinders University, drew data from the Study of Osteoporotic Fractures (SOF), a prospective cohort of 9,704 women aged 65 years and older. Coffee and tea intake were assessed at four separate visits over approximately ten years, while the mineral density of their bones was measured at the femoral neck and total hip using dual-energy X-ray absorptiometry (DXA), two areas strongly linked to fracture risk.
The researchers employed linear mixed-effects models to account for demographics, physical activity, comorbidities, and medication use, with nonlinear relationships assessed using natural splines. Subgroup analyses explored interactions between beverage consumption and factors like alcohol intake and body mass index (BMI).
Over the ten-year period, the researchers found that “tea consumption was associated with higher total hip BMD in postmenopausal women, whereas excessive coffee intake (>5 cups/day) may adversely affect BMD.”
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Tea consumption was associated with a modest, yet statistically significant, increase in the total mineral density of the hip bones, with the researchers suggesting that “tea consumption appeared particularly beneficial for those with obesity.”
Adjunct Associate Professor Enwu Liu from the College of Medicine and Public Health commented, “Even small improvements in bone density can translate into fewer fractures across large groups.”
Coffee consumption, on the other hand, showed a different picture. Moderate coffee consumption, about two to three cups per day, did not appear to adversely affect bone health. However, consuming more than five cups daily was linked to lower BMD, particularly at the femoral neck. Interaction analyses revealed that women with higher lifetime alcohol consumption were more susceptible to the negative effects of excessive coffee.
Ryan Liu, co-author of the paper, explained the potential biological mechanisms behind these findings. “Compounds called catechins, abundant in tea, may promote bone formation and slow bone breakdown. 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,” he said.
Adjunct Associate Professor Enwu Liu added, “While moderate coffee drinking appears safe, very high consumption may not be ideal, especially for women who drink alcohol.” He further noted, “Our results don’t mean you need to give up coffee or start drinking tea by the gallon. 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.”
Limitations of the study
The authors caution that several limitations must be considered when interpreting these findings. One key concern relates to how coffee and tea consumption were measured. Intake was self-reported, which may introduce measurement bias. As the researchers note, assessing beverage consumption only in terms of the number of cups per day, without accounting for cup size, beverage strength, or type, could have contributed to inaccuracies.
In addition, intrinsically time-varying factors such as physical activity and alcohol consumption were treated as time-independent, as they were assessed only at baseline. This approach may have introduced recall bias and limited the ability to capture changes in lifestyle over time.
Another limitation stems from the long follow-up period of nearly a decade, which resulted in high rates of mortality and missing data. While the statistical models used in the analysis can handle missing data under the assumption of missing at random (MAR), the authors acknowledge that “this assumption may not fully hold,” potentially introducing bias into the results.
Despite extensive adjustment for demographic, lifestyle, and clinical factors, residual confounding cannot be entirely ruled out. The researchers also emphasised that although the difference in bone mineral density between tea drinkers and non-drinkers was statistically significant, it falls below the threshold typically considered clinically meaningful for individual patient management. However, they note that “such a small difference may still be relevant from an epidemiological and public health perspective,” as even modest shifts in population-level BMD could translate into fewer fractures at the group level.
The authors further stress that future longitudinal studies, particularly those using fracture incidence as a primary endpoint, are needed to determine whether the small BMD differences associated with tea consumption actually result in meaningful reductions in osteoporotic fractures over time.
Finally, the study population consisted almost entirely of White older women in the United States, which significantly limits the generalisability of the findings. Because bone mineral density, fracture risk, and dietary habits vary across racial and ethnic groups, the researchers caution that “our results should be interpreted with considerable caution when applied outside this demographic.”
Why moderation matters: expert advice
Commenting on the study, Dr Anup Khatri, Senior Consultant – Orthopaedics at Gleneagles Hospital, Mumbai, said the findings are biologically plausible and align with what clinicians see in practice. He explained that high caffeine intake is known to interfere with calcium balance in the body. “Excess caffeine reduces calcium absorption from the gut and increases calcium loss through urine. While it may not directly cause osteoporosis, it can certainly act as a contributing factor to lower bone mineral density,” he said.
Dr Khatri pointed out that older women are particularly vulnerable because multiple risk factors often converge. “Elderly women already have lower estrogen levels after menopause, along with reduced calcium and vitamin D intake. When high caffeine consumption is added to this, the overall fracture risk increases,” he noted. He added that, in this sense, the study’s conclusions are relevant to Indian women as well, especially those above 65 years of age and post-menopausal.
Highlighting population-specific differences, Dr Khatri said the findings may carry greater relevance for India. He noted that the study was conducted largely among older women in Western countries, whereas Indian women often face a higher burden of nutritional deficiencies, particularly related to vitamin D and calcium intake. “These factors already contribute to lower bone mineral density in Indian women,” he explained.
As a result, he cautioned that the impact of coffee on bone health may appear at lower levels of consumption. “While studies from Western populations suggest that drinking more than five cups of coffee a day increases bone-related risk, in the Indian context, even three to four cups daily could potentially raise fracture risk,” Dr Khatri said.
On the question of tea versus coffee, Dr Khatri urged caution. “While the study suggests that tea consumption was linked to a small increase in hip bone mineral density, there is no strong scientific evidence to say tea is universally better than coffee,” he said. Instead, he emphasised that individual risk assessment is far more important. “A woman’s age, menopause status, baseline BMI, prior fractures, DEXA scan results, and daily calcium and vitamin D intake must all be considered before making dietary recommendations.”
For those at higher fracture risk, he suggested moderation rather than elimination. “If someone consumes a high amount of black coffee, switching to tea with less or no sugar, and adding milk, can help increase calcium intake.”
Addressing broader lifestyle factors, Dr Khatri noted that diet and physical activity often have a greater impact on bone health than caffeine alone. “Adequate calcium intake, at least 800 milligrams per day for the Indian population, along with optimal vitamin D levels, regular weight-bearing and resistance exercises, and limiting alcohol and smoking, are far more important,” he said. He added that a balanced diet rich in protein, fruits, vegetables, and seeds, while avoiding excess salt, plays a critical role in maintaining bone strength.
Dr Khatri cautioned against viewing tea or coffee as a cure-all or a singular risk. “It’s not that drinking a lot of tea will automatically protect bones or that coffee alone will damage them. What matters is balance,” he said. “When all these factors are addressed together, bone health can be effectively protected in the long run.”
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS.
