Analysis of 69 clinical trials and 150,000 people finds minimal benefit — while older studies link supplements to higher kidney stone and heart disease risk
"Calcium is good for your bones" passes for common knowledge. For middle-aged and older adults worried about osteoporosis, calcium supplements are usually the first thing they reach for.
But do calcium supplements actually strengthen bones and prevent fractures? Decades of research point to a more complicated answer than most people expect.
Study of 150,000 people finds little fracture-prevention benefit
A research team from Montreal, Canada, published findings in the British Medical Journal in May, pooling results from 69 clinical trials on the effectiveness of calcium and vitamin D supplements in preventing fractures and falls. The analysis covered 153,902 adults.
Taking calcium alone, vitamin D alone, or both together showed almost no effect in preventing fractures. When calcium and vitamin D were taken together, fracture risk fell slightly in statistical terms, but the benefit amounted to roughly one fewer fracture for every 100 people who took the supplements.
The results held when the research team broke down participants by age, sex, history of fractures or falls, and habitual dietary calcium intake.
The research team concluded that "there is no basis for recommending that everyone take calcium or vitamin D supplements to prevent fractures and falls."
However, most of the trials included in the analysis involved generally healthy adults not at elevated fracture risk, making it difficult to apply the findings directly to patients already undergoing treatment for osteoporosis.
Bone density up 1%, but kidney stone risk rose 17%
A large-scale US clinical trial conducted about two decades ago reached similar conclusions.
The Women's Health Initiative research team published results in the New England Journal of Medicine in 2006 after giving 36,282 postmenopausal women 1,000 milligrams of calcium and 400 IU of vitamin D daily for seven years.
Women who took the calcium and vitamin D supplements showed hip bone density about 1 percent higher than those who took a placebo.
Hip fracture rates, however, did not fall significantly. Instead, kidney stone risk rose 17 percent.
An even larger controversy surrounding calcium supplements involves the heart.
A research team led by Myung Seung-kwon, a professor at the National Cancer Center, published findings in the journal Nutrients in 2021, pooling results from 13 double-blind clinical trials involving about 29,000 people.
People who took calcium supplements faced a 15 percent higher risk of cardiovascular disease and a 16 percent higher risk of coronary artery disease, the research found.
Myung's team said that unlike dietary calcium, supplements rapidly raise blood calcium levels, which may cause calcium to accumulate in blood vessels or promote clotting.
Other studies have reached the opposite conclusion.
The National Osteoporosis Foundation published findings in the journal Osteoporosis International in 2016, pooling data from eight clinical trials in which participants took calcium and vitamin D together, covering 30,970 people.
People who took calcium and vitamin D together had a 15 percent lower risk of any fracture and a 30 percent lower risk of hip fracture compared with those who took a placebo.
The research team said "no benefit can come without actually taking the supplement," arguing that measuring calcium's effect requires looking at people who genuinely adhered to the regimen.
When two trials focused solely on elderly residents in care facilities were examined separately, overall fracture risk was 33 percent lower. By contrast, six trials involving community-dwelling individuals showed no statistically significant reduction in overall fracture risk.
References
DOI: 10.1136/bmj-2025-088050
Massé O, et al. Calcium, vitamin D, or combined supplementation to prevent fractures and falls: systematic review and meta-analysis. BMJ. 2026;393:e088050.
DOI: 10.1056/NEJMoa055218
Jackson RD, LaCroix AZ, Gass M, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006;354(7):669-683.
DOI: 10.3390/nu13020368
Myung SK, Kim HB, Lee YJ, Choi YJ, Oh SW. Calcium supplements and risk of cardiovascular disease: a meta-analysis of clinical trials. Nutrients. 2021;13(2):368.
DOI: 10.1007/s00198-015-3386-5
Weaver CM, Alexander DD, Boushey CJ, et al. Calcium plus vitamin D supplementation and risk of fractures: an updated meta-analysis from the National Osteoporosis Foundation. Osteoporos Int. 2016;27(1):367-376.
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