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Calcium Supplements After 50: What the Trials Show About Benefits and Risks

ByBones After 50 Editorial Team

Short answer: calcium supplements raise bone density by a small amount, have not been shown to cut fractures in healthy older women, and carry a measurable risk of kidney stones. Food is the better first move. A supplement can still make sense to fill a real gap. Here is what the trials found.

Not medical advice. If you have had kidney stones, have kidney or heart disease, or take thyroid medication or other drugs that interact with calcium, ask your doctor before starting or stopping a supplement.

How much calcium do you actually need?

The US recommended daily amount for adults over 50 is 1,200 mg for women, and 1,000 mg for men aged 51 to 70 rising to 1,200 mg after 70. That figure counts everything you eat and drink plus any supplement. The tolerable upper limit for adults over 50 is 2,000 mg a day (NIH Office of Dietary Supplements). Many people already get 600 to 900 mg from food, so the gap to fill is often a few hundred milligrams, not the whole 1,200.

What 59 trials say about bone density

A 2015 BMJ meta-analysis pooled 59 randomised trials in people over 50 (Tai and colleagues). Raising calcium intake from food or from supplements increased bone mineral density by roughly 0.6 to 1.8%, and the gain did not keep growing over time. The authors concluded that these small, non-progressive increases are unlikely to lead to a clinically meaningful drop in fracture risk. Food and supplements gave similar bone-density results.

The Women’s Health Initiative: fractures and kidney stones

The largest single trial gave 36,282 postmenopausal women aged 50 to 79 either 1,000 mg of calcium (as carbonate) with 400 IU of vitamin D3 daily or a placebo, for an average of seven years (Jackson 2006).

  • Hip bone density was 1.06% higher in the supplement group.
  • Hip fracture risk was not significantly lower (hazard ratio 0.88, 95% confidence interval 0.72 to 1.08), and total fractures barely changed (0.96, 0.91 to 1.02).
  • Kidney stones were more common with the supplement (hazard ratio 1.17, 1.02 to 1.34).

When the researchers looked only at women who actually kept taking the tablets, the hip fracture hazard ratio fell to 0.71 (0.52 to 0.97). That is a secondary analysis, and it can be skewed by who sticks with a study, so it is a reason for more research rather than proof of benefit.

Heart risk: a real but disputed signal

A 2010 BMJ meta-analysis of trials of calcium supplements of at least 500 mg a day found more heart attacks in the calcium groups (hazard ratio 1.31, 1.02 to 1.67 in the five trials with patient-level data), with non-significant increases in stroke and death (Bolland 2010). The finding drew many letters and remains debated. A later re-analysis of the same data found no subgroup, by age, diet, weight or history, that was clearly spared or clearly harmed (Radford 2013). For you, the practical reading is: do not take more calcium than you need, and be cautious if you already have heart disease.

What to do

  1. Count your food calcium first. Our guide to calcium-rich foods for osteopenia and dairy-free calcium sources will show you how close you already are.
  2. Supplement only the gap. If food gives you 700 mg, a 500 mg tablet gets you to about 1,200 mg. A 1,200 mg tablet on top of a good diet pushes you toward the upper limit.
  3. Keep doses at or below about 500 mg at a time. NIH notes that absorption is best in doses of 500 mg or less. Take calcium carbonate with food; calcium citrate can be taken at any time.
  4. Do not rely on calcium alone. Vitamin D status, protein, and loading exercise matter more for fracture risk. See our prevention plan.
  5. Tell your doctor if you have had kidney stones, have kidney disease, or have been told to limit calcium.

Where this leaves the “take 1,200 mg of calcium” advice

Books and guides that list a fixed calcium supplement as a daily habit, including The Bone Density Solution (see our habit-by-habit check), are giving a sensible target but skipping the nuance: the target is a total from food and pills, and the evidence for adding pills is modest.

References

  • Tai V, et al. Calcium intake and bone mineral density: systematic review and meta-analysis. BMJ 2015;351:h4183. PubMed
  • Jackson RD, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med 2006;354:669-83. PubMed
  • Bolland MJ, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ 2010;341:c3691. PubMed
  • Radford LT, et al. Subgroup analysis for the risk of cardiovascular disease with calcium supplements. Bonekey Rep 2013;2:293. PubMed
  • NIH Office of Dietary Supplements. Calcium fact sheet for health professionals. ods.od.nih.gov

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