Coffee drinkers don't realise this:  Taking 1-3 cups of coffee a day may stop your body from naturally absorbing calcium from your daily food intake. 


It should concern people aged 50 and above. That's because it may lead to weakening of bones, something which shows no symptoms. You get to be aware of bone density loss either from a bone density scan or if you fracture your bones during a fall.


The following studies deal with the relationship between taking coffee and losing calcium from your body. 


There is, however, some good news for coffee addicts: The Rancho Bernardo Study. It suggests that coffee drinkers should drink at least one glass of milk each day to make up for the calcium being stolen by caffeine.



1.  Caffeine from coffee and tea modestly increases calcium excretion and reduces absorption of calcium:  Effects of nitrogen, phosphorus, and caffeine on calcium balance in women'. Heaney RP, Recker RR., Journal of Laboratory and Clinical Medicine 99(1):46-55 · February 1982. 



  • This study is a review of the effects of different levels of nitrogen, phosphorus, and caffeine intake on calcium balance and on certain of its components as assessed in 170 studies in normal middle-aged, but still premenopausal women. 

  • Statistically significant negative associations with calcium balance were found for ... caffeine,... Higher nitrogen intakes were associated with proportionately higher levels of urinary calcium; higher phosphorus intake was associated with slightly lower levels of urinary calcium but also with slightly more intestinal secretion of calcium.... 

  • Caffeine intake was associated with higher levels of both urinary calcium and intestinal calcium secretion. None of the three intake variables was associated with differences in calcium absorption efficiency. Both the nitrogen and the caffeine effects were proportional to intake. The magnitude of the effects observed was such that a 50% increase in intake of nitrogen above the group mean intake value would be predicted to result in calcium balance shift of -0.032 gm/day. For caffeine, the corresponding calcium balance shift would be predicted to be -0.006 gm/day.


2.  Effects of dietary caffeine on renal handling of minerals in adult women

 Ethan A.Bergman Ph.D. Linda K.Massey Ph.D.Kevin J.Wise M.S. Donald J.Sherrard M.D. [1990 study]




Thirty-seven women, aged 31–78 years, on two separate mornings consumed a decaffeinated beverage to which 6 mg caffeine/kg lean body mass or no caffeine were added. Total urine output of water, calcium, magnesium, sodium, chloride, potassium and creatinine increased in the two hours following caffeine ingestion when compared to the control beverage. 

Increased urinary mineral (mg)/urinary creatinine (g) ratios were seen for calcium (120 to 200), magnesium (70 to 110), sodium (3,800 to 6,200) and chloride (9,200 to 14,800), following the caffeinated beverage. Creatinine clearance did not change significantly. The percent reabsorption of calcium (98.6% to 97.5%, p<.001) and magnesium (97.0% to 94.2%, p<.0001) decreased significantly during the post-caffeine period. The calcium and magnesium filtered loads did not differ significantly between the caffeine and no caffeine beverages. 


Therefore, caffeine-induced urinary loss of calcium and magnesium is largely attributable to a reduction in calcium and magnesium renal reabsorption, although the physiological mechanism and tubular segment affected remain to be established.


3.  Caffeine, Urinary Calcium, Calcium Metabolism and Bone

Linda K.Massey Susan J. Whiting The Journal of Nutrition, Volume 123, Issue 9, September 1993,



01 September 1993

Abstract  Oral doses of caffeine increase the urinary excretion of calcium, magnesium, sodium and chloride for at least 3 h after consumption. The hypercalciuric effect can be blocked by adenosine receptor agonists. The effect is proportional to dose per lean body mass and no adaptation to the urinary losses occurs with continuing consumption of caffeine.... 



4.  Caffeine intake (two to three or more cups of coffee per day) will result in bone loss, but only in individuals with low milk or low total calcium intake:


The Rancho Bernardo Study, JAMA The Journal of the American Medical Association  271(4):280-3   February 1994 Source:  PubMed Barrett-Connor et al., 1994; 


 Coffee-associated osteoporosis offset by daily milk consumption. The Rancho Bernardo Study

JAMA The Journal of the American Medical Association 271(4):280-3 ·  February 1994 

Source:  PubMed Barrett-Connor et al., 1994;  Elizabeth Barrett-Connor, MD, FACP, FAHA, graduated from Mount Holyoke College with a bachelor of science degree in zoology. Continuing her studies, Elizabeth earned her doctor of medicine degree from Cornell University Medical College in 1960. She is internationally acclaimed with a stellar record of research accomplishments (over one thousand original research publications), is on all the highly cited researcher lists, has been a principal investigator on numerous major population studies and multi center clinical trials, and has received extensive grants and awards. Her immense impact is not just in research but is also reflected through her teaching, encouragement, and mentorship of generations of physicians and scientists:

Abstract   To describe the association of lifetime intake of caffeinated coffee, in cup-years, to bone mineral density (BMD) of the hip and spine in postmenopausal women; and to determine the effect of regular milk intake on this association. 

Women from an established epidemiologic cohort had measures of BMD and gave a medical and behavioral history that included caffeinated coffee and daily milk intake between the ages of 12 and 18 years, 20 and 50 years, and 50 years of age and older. A community-based population of older women, Rancho Bernardo, Calif. All 980 postmenopausal women aged 50 to 98 years (mean age, 72.7 years) who participated between 1988 and 1991. Bone density at the hip and lumbar spine measured by dual energy x-ray absorptiometry. 


There was a statistically significant graded association between increasing lifetime intake of caffeinated coffee and decreasing BMD at both the hip and spine, independent of age, obesity, parity, years since menopause, and the use of tobacco, alcohol, estrogen, thiazides, and calcium supplements. 


Bone density did not vary by lifetime coffee intake in women who reported drinking at least one glass of milk per day during most of their adult lives. 


Lifetime caffeinated coffee intake equivalent to two cups per day is associated with decreased bone density in older women who do not drink milk on a daily basis.


5.  Caffeine and bone loss in healthy postmenopausal women

S S Harris B Dawson-Hughes The American Journal of Clinical Nutrition, Volume 60, Issue 4, October 1994, Pages 573–578,



01 October 1994

The effects of caffeine consumption on rates of change in bone mineral density (BMD) were

Examined in 205 healthy, non smoking, postmenopausal women. BMD of the spine and total

Body were measured by dual-energy x-ray absorptinmetry, and dietary intakes by food frequency



Among women with calcium intakes above the median (744 mg/d), 1-y rates of bone change –

Adjusted for years since menopause, body mass index, physical activity, and baseline BMD -

did not differ by caffeine intake.


However, among women consuming less calcium, those with the highest caffeine intake (.450mg/d)

Had significantly more bone loss (ANCOVA, P <0.05) than did women consuming less caffeine

(0-171 and 182-419 mg/d). Percent change in BMD by lowest to highest tertile of caffeine

consumption was  0.26 ± 2.74, 0.70 ± 2.70 and −1.36 ± 2.70 at the spine and −0.19 ± 1.24, 0.23 ± 1.23, and −0.68 ± 1.25 at the total body. 

Daily consumption of caffeine in amounts equal to or greater than that obtained from about two to three servings of brewed coffee may accelerate bone loss from the spine and total body in women with calcium intakes below the recommended dietary allowance of 800 mg.


Harris and Dawson-Hughes, 1994):