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Coffee and Bone Health: Does Your Cup Cost You Calcium?

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Quick answer: A cup of coffee costs your skeleton very little. Caffeine slightly lowers how much calcium the gut absorbs, about 4.6 mg per 177 ml serving in one balance study, and a splash of milk makes up the difference. For adults who get enough calcium in their diet, no solid evidence shows that moderate coffee weakens bones. The one warning sign in the research sits with heavy drinkers, four cups a day or more, who also eat little calcium.

Key points
  • One 177 ml serving of caffeinated coffee made calcium balance 4.6 mg per day more negative, which about 40 mg of extra calcium offsets (1995 balance study)
  • EFSA sets the calcium reference intake for adults at 950 mg per day from age 25 and 1,000 mg for ages 18 to 24
  • In a Swedish cohort of 31,527 women, the extra fracture risk tied to coffee was confined to those eating under 700 mg of calcium a day
  • Meta-analyses disagree: a 2014 pooled analysis found more fractures in women and fewer in men, while a 2023 one found no link with hip fracture
  • A 2025 Mendelian randomisation analysis found no causal effect of coffee on femoral neck bone density
  • With a diagnosed bone condition, discuss coffee with your doctor rather than relying on a general figure

What does a cup of coffee cost your calcium balance?

Less than most people assume. The classic figure comes from Barger-Lux and Heaney, who in 1995 reviewed 560 calcium balance studies on 190 women aged 34.8 to 69.3. Each 6 fl oz (177 ml) serving of caffeinated coffee pushed daily calcium balance down by 4.6 mg, and the shortfall appeared on the intake side: women absorbed a little less calcium, with no sign of extra loss. By the authors' arithmetic, roughly 40 mg of additional calcium per serving would cancel it.

Heaney's 2002 review went further. Caffeine's depressant effect on intestinal absorption is very small, it has no effect on total 24-hour urinary calcium, and one to two tablespoons of milk are enough to offset it. Every study linking coffee to osteoporosis came from populations eating well under the optimal amount of calcium, and nothing shows harm in people who meet the recommended intake.

For scale, EFSA's 2015 opinion puts the reference intake at 950 mg a day for adults aged 25 and over.

What do the large fracture studies show?

The pooled data are mixed. Lee and colleagues (2014) combined 15 studies covering 253,514 people and 12,939 fractures. The highest coffee intake carried a relative risk of 1.14 in women (95% CI 1.05 to 1.24) but 0.76 in men (0.62 to 0.94). In the dose-response analysis for women, two cups a day gave a relative risk of 1.02 and eight cups 1.54.

A Swedish cohort sharpens the picture. Hallström and colleagues (2006) followed 31,527 women aged 40 to 76 for 10.3 years and counted 3,279 osteoporotic fractures. Caffeine above 330 mg a day, compared with under 200 mg, gave a hazard ratio of 1.20 (1.07 to 1.35), and tea showed no link. Among women taking in less than 700 mg of calcium daily, four or more cups against under one cup gave 1.33 (1.07 to 1.65).

Later syntheses move the needle back toward neutral. Chen and colleagues (2023) pooled 20 studies and 508,312 people and found no association with hip fracture (HR 1.008, 0.760 to 1.337). Zeng and colleagues (2022) reported lower odds of osteoporosis for the highest coffee group (OR 0.79, 0.65 to 0.92), a hip fracture curve that dips between one and four cups a day, and a result that weakened in larger, higher-quality studies.

Why does the evidence keep pointing in different directions?

Almost everything here is observational. Heaney points out that milk and caffeinated drinks tend to trade places in the diet, so high caffeine intake often marks a low calcium intake, and low calcium is clearly linked to fragile bones. Smoking, alcohol, activity and menopausal status add further noise, handled differently from study to study. The reason for the gap between women and men in the 2014 analysis remains unexplained.

What about bone mineral density?

Density studies show little either way. The Study of Osteoporotic Fractures followed 9,704 women aged 65 and over for around ten years and found no overall link between coffee and hip or femoral neck density, though splines hinted at lower values above five cups a day (Liu and Liu, 2025). Wang and colleagues (2025) combined 5,915 NHANES participants with Mendelian randomisation and found no association and no causal effect on femoral neck density (OR 1.06, 0.88 to 1.27). A separate 2024 Mendelian randomisation study by Ye and colleagues pointed to a small positive association with total body density.

How should a coffee lover approach bone health?

The International Osteoporosis Foundation estimates that worldwide one in three women and one in five men over 50 will have an osteoporotic fracture, so the diet around the cup matters more than the cup itself.

  • Reach your calcium target first: 950 mg a day for most adults.
  • Count the milk in your flat white or cappuccino, or choose a calcium-fortified plant drink (check the label).
  • Stay within EFSA's 400 mg of caffeine a day; our caffeine comparison by brew method helps you count.
  • Be cautious beyond four cups when calcium intake is low, the profile where a signal appeared.

Coffee has a stronger documented effect on a different mineral: see coffee and iron absorption.

Frequently asked questions

Does coffee cause osteoporosis?

No solid evidence says it does. A 2022 meta-analysis found lower odds of osteoporosis in the highest coffee group (OR 0.79), and a 2023 one found no link with hip fracture. Caffeine's effect on calcium is small and an adequate calcium intake offsets it.

How much coffee is safe for your bones?

No validated threshold exists. EFSA's general benchmark is 400 mg of caffeine a day for a healthy adult. A risk signal appeared at four or more cups a day among Swedish women eating under 700 mg of calcium daily, and a 2025 cohort hinted at lower density beyond five cups.

Should I add milk to coffee to protect my bones?

Milk covers the small loss: one to two tablespoons suffice according to Heaney's review. The bigger lever is total calcium across the day, 950 mg for adults aged 25 and over.

Is tea better than coffee for bones?

Not demonstrably. Tea was unrelated to fracture risk in the Swedish cohort, hip density was only 0.003 g/cm² higher in tea drinkers in the 2025 US study, and the 2023 meta-analysis found no significant association for tea (HR 0.93, 0.84 to 1.03).

Related reading: Caffeine effects and health guide · Coffee and health research guide · Coffee and iron absorption · Coffee in pregnancy

Sources

  1. EFSA NDA Panel (2015), Scientific Opinion on Dietary Reference Values for calcium, EFSA Journal 13(5):4101. doi:10.2903/j.efsa.2015.4101
  2. EFSA NDA Panel (2015), Scientific Opinion on the safety of caffeine, EFSA Journal 13(5):4102. doi:10.2903/j.efsa.2015.4102
  3. Barger-Lux MJ, Heaney RP (1995), Caffeine and the calcium economy revisited, Osteoporosis International. PubMed 7599455
  4. Heaney RP (2002), Effects of caffeine on bone and the calcium economy, Food and Chemical Toxicology. PubMed 12204390
  5. Hallström H et al. (2006), Coffee, tea and caffeine consumption in relation to osteoporotic fracture risk in a cohort of Swedish women, Osteoporosis International. PubMed 16758142
  6. Lee DR et al. (2014), Coffee consumption and risk of fractures: a systematic review and dose-response meta-analysis, Bone. PubMed 24576685
  7. Zeng X et al. (2022), The association of coffee consumption with the risk of osteoporosis and fractures: a systematic review and meta-analysis, Osteoporosis International. PubMed 35426508
  8. Chen CC et al. (2023), Association of Coffee and Tea Intake with Bone Mineral Density and Hip Fracture: A Meta-Analysis, Medicina 59(6):1177. doi:10.3390/medicina59061177
  9. Ye Y et al. (2024), Association of coffee intake with bone mineral density: a Mendelian randomization study, Frontiers in Endocrinology. doi:10.3389/fendo.2024.1328748
  10. Wang K et al. (2025), The association between coffee intake and femoral neck bone mineral density based on the NHANES and Mendelian randomisation study, Journal of Nutritional Science. doi:10.1017/jns.2024.38
  11. Liu RY, Liu E (2025), Longitudinal association of coffee and tea consumption with bone mineral density in older women, Nutrients 17(23):3660. doi:10.3390/nu17233660
  12. International Osteoporosis Foundation, Epidemiology of osteoporosis and fragility fractures. osteoporosis.foundation