Excessive coffee consumption may weaken bone density in older women

A decade-long study of postmenopausal women suggests that tea may offer modest bone benefits, while very high coffee consumption could raise concerns about future hip strength.

Study: Longitudinal association of coffee and tea consumption with bone mineral density in older women: a repeated measures analysis over 10 years in the osteoporotic fracture study. Image Credit: osobystist/Shutterstock.com

Despite high rates of consumption, it is still unclear whether tea and coffee intake has an impact on bone health. A recent study published in Nutrients examines longitudinal associations between coffee and tea consumption and bone mineral density (BMD) in older women.

The global osteoporosis epidemic

Osteoporosis is a disease characterized by a reduction in BMD, which subsequently leads to weak, brittle bones and an increased risk of fractures, especially in the hip, spine and wrist. Osteoporosis is a major global public health challenge that affects people of all ages, genders and ethnicities.

Globally, approximately one in three women and one in five men aged 50 and older experience an osteoporotic fracture. According to the 2021 Global Burden of Disease Study, low BMD causes millions of years of disability and around 477,000 deaths each year, with approximately 71% of these deaths directly attributable to low bone mineral density.

Compared to men, women are particularly vulnerable to developing osteoporosis due to their lower bone mass and a greater likelihood of experiencing more rapid bone loss after menopause. Osteoporotic fractures cause serious health problems and significantly increase health costs and long-term disability.

Coffee and tea are among the most popular beverages around the world. Both drinks contain caffeine, a compound widely studied for its health effects, including its impact on bone metabolism. Despite these studies, the effect of coffee or tea intake on BMD remains unclear.

Evaluation of the effect of tea and coffee consumption on bone health

In the current study, researchers evaluate the effects of tea and coffee intake on bone health using repeated measures data from the Study of Osteoporotic Fractures (SOF), a long-term multicenter study. The SOF cohort monitored a total of 9,704 women aged 65 years or older for approximately 20 years, and all patients were seen by study physicians every two years.

BMD, as well as data on coffee and tea intake, were collected from study participants at visits two, four, five, and six over a total period of 10 years. Other visits were excluded due to missing data, except for visits eight and nine, which were used for sensitivity analyses.

All study participants completed a questionnaire about coffee and tea consumption. Total femoral neck and hip bone density were measured at visits two, four, five, and six, with visit six considered the primary endpoint.

Associations between beverage intake and bone density were analyzed using minimally and fully adjusted linear mixed-effects models. Subgroup analyzes were conducted to determine whether results differed by participant characteristics, using interaction terms in the models.

Associations between coffee, tea and bone density

After exclusions for deaths and missing data, the final analysis included 24,638 observations. The average follow-up period was about eight years.

Over 10 years, bone density decreased slightly, with femoral neck BMD decreasing from 0.65 to 0.62 g/cm2, while total hip BMD decreased from 0.76 to 0.73 g/cm2. During this period, the mean age of the study cohort increased from 73 to 80 years, while BMI remained at approximately 26. Comorbidity scores increased with age, while smoking prevalence decreased across the cohort.

Those who did not drink coffee or tea were more likely to consume more calcium, while coffee drinkers reported slightly lower protein intake and higher alcohol intake. Tea drinkers reported slightly higher protein intake and lower alcohol intake than non-tea drinkers.

Physical activity was similar in all groups. About 15% of study participants received oral estrogens and less than 3% used steroid pills at the start of the study.

Tea consumption was associated with a small, statistically significant but clinically modest increase in total hip BMD at visit six, and this association persisted after adjusting for other factors. The observed difference was approximately 0.003 g/cm2, which the authors believe may be below thresholds typically considered clinically significant at an individual level. Drinking two or three cups of coffee a day showed little evidence of affecting bone density; However, spline analyzes suggested that drinking five or more cups of coffee per day may be associated with lower BMD. Tea intake showed a weak but positive relationship with total hip BMD.

The effect of coffee on femoral neck BMD was more positive for those who drank less alcohol, while the effect of tea was greater for obese women in interaction analyses. Sensitivity analyzes using extended follow-up data indicated that high coffee consumption was associated with lower femoral neck BMD at visit nine. In contrast, the association between tea consumption and higher total hip BMD was observed at visits six and eight, but not at visit nine.

Advanced models confirmed that while the primary models did not show a statistically significant association between coffee consumption and BMD, consuming more than five cups of coffee a day suggested lower BMD. In extended sensitivity analyses, the relationship between tea and total hip BMD was generally positive but not strictly linear..

Tea shows promise as bones age

Tea consumption correlates with slightly higher total hip BMD in older postmenopausal women. Although there is no general association between coffee Consumption and BMD were observed during the 10-year follow-up period; consuming more than five cups of coffee per day may be associated with lower BMD. based on suggestive non-linear patterns.

Coffee negatively affected femoral neck BMD in women with higher alcohol consumption, while tea was particularly beneficial among women with obesity in subgroup analyzes that should be considered hypothesis generating. Taken together, these findings highlight the importance of personalized dietary counseling to promote bone health in older women, while recognizing that the study population was primarily comprised of older white women in the United States, which may limit the generalizability of the findings. to more diverse populations.

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