Do calcium supplements prevent fractures?

What the largest review found

A 2026 review pooled 69 randomized trials in adults who did not take osteoporosis medicines. In most of the trials, people lived at home (87% of trials) and were not at high risk of fractures or falls (73%).^[1]

It gives its results as a risk ratio: 1.00 means no difference, and 0.91 means 9% lower risk. For any fracture:^[1]

• Calcium alone. Risk ratio 0.91 in 11 trials with 9,067 people, and the result could be due to chance.^[1]
• Vitamin D alone. Risk ratio 1.00 in 36 trials with 92,045 people.^[1]
• Calcium with vitamin D. Risk ratio 0.91 in 15 trials with 51,126 people.^[1]

The authors looked at how many fractures this would prevent in absolute numbers. They concluded that the benefit is little to none, for fractures and for falls.^[1]

Older reviews disagreed

• A 2019 review of 6 large trials of calcium with vitamin D (49,282 people) found 6% fewer fractures of any kind and 16% fewer hip fractures.^[3]
• A 2016 review of 8 studies (30,970 people) found 15% fewer fractures and 30% fewer hip fractures. Its authors noted a limit: it used subgroup data from one large trial.^[4]
• A 2017 review of 33 trials in adults over 50 living at home (51,145 people) found no link between supplements and fractures.^[5]
• A 2015 review found 11% fewer fractures overall with calcium. It found no effect in the 4 trials with the lowest risk of bias (44,505 people) and called the evidence weak and inconsistent.^[6]

The largest single trial followed 36,282 women aged 50 to 79 for 7 years. They took 1,000 mg of calcium with 400 IU of vitamin D or a placebo. Hip bone density was 1.06% higher, but the 12% drop in hip fractures could be due to chance.^[7]

In the US, a health claim for calcium with vitamin D and osteoporosis is approved, but not all research supports it.^[8]

What happens to bone density

In 51 trials of supplements in people over 50, bone density rose by 0.7% to 1.8%. The gain at later time points was about the same as at one year, and calcium from food gave a similar gain.^[9] A smaller group of studies looked at younger people:

• In 7 trials in women before menopause (941 people), neither calcium nor vitamin D gave a clinical difference in bone density at the hip or spine.^[10]
• In 19 trials in healthy children (2,859 children), calcium had no effect at the hip or spine, and a small effect in the arms.^[11]

Who may gain more

The 2026 review had limited evidence on people at high risk and people in residential care.^[1] A 2015 review noted that only one trial, in frail older women in care with low calcium intake and low vitamin D, showed a clear drop in fractures.^[6]

A later trial in 60 Australian care homes (7,195 residents, mean age 86) added milk, yogurt and cheese. This gave 562 mg more calcium and 12 g more protein a day. Over 2 years there were 33% fewer fractures, 46% fewer hip fractures and 11% fewer falls.^[2] This trial tested food with protein, not a calcium tablet.^[2]

Who should be careful

Calcium with vitamin D raised the risk of kidney stones by 17% in the largest trial.^[7] Stomach problems are also common.^[12] One expert review argues that supplements have little role in osteoporosis care, because estrogen and bisphosphonates prevent fractures without added calcium.^[12]

People who take a medicine every day, including one for osteoporosis, should ask a doctor or pharmacist before they start or stop calcium.^[8]