Do calcium and vitamin D supplements really help against bone loss?
Calcium and vitamin D together can improve bone density and slightly reduce the risk of hip fractures when a deficiency has been confirmed. Vitamin D as a standalone supplement does little if your blood levels are already adequate.
Calcium and vitamin D together can improve bone density and reduce the risk of hip fractures when there is a deficiency. Vitamin D on its own does little for your bones if you are not deficient: many studies combined, covering more than 4,000 participants across 23 studies, found only a small effect at the hip (+0.8%) and no effect anywhere else.
The combination works better. Studies in women after the menopause show that calcium plus vitamin D improves bone density at several sites and reduces the risk of a hip fracture by around 14%. That benefit was found mainly with fortified dairy products, and less clearly with separate pills. For a lasting effect, postmenopausal women took 1,000 to 1,200 mg of calcium per day combined with 800 IU of vitamin D (a measure of the amount), for at least one to two years. Always discuss this with your doctor. Choose a tablet that lists 'Calcium (elemental)' in milligrams and vitamin D in IU, as calcium carbonate or calcium citrate. Which form of vitamin D is used matters less for your bones than the dose.
Supplements only make sense when a deficiency has been confirmed. You need a blood level of at least 32 ng/mL for good calcium absorption and protection against fractures; many people, especially those with darker skin, are well below that. If your levels are already adequate, taking extra supplements offers little benefit. Fortified dairy products are in any case preferable to separate pills.
Are you already taking medication for osteoporosis, such as bisphosphonates? Studies combining results from 37 studies with more than 43,000 patients show that adding vitamin D reduces digestive side effects and lowers the risk of death. In that context, calcium did not clearly help bone density or reduce fractures. Supplements play a supporting role here, not a replacement: bisphosphonates and denosumab are by far the best supported treatments for confirmed osteoporosis. Fall prevention and addressing physical frailty in older adults also help reduce fractures.
The claims are based on many studies combined, including large groups of participants, as well as a review article. The strongest evidence covers two points: vitamin D alone helps little, and medications work best. For the combination of calcium and vitamin D, the evidence is moderate: there is a modest benefit, but it depends on the form and the dose.
Does strength training help against bone loss (osteoporosis)?
Strength training helps to increase or maintain bone density, but the effect is modest and a reduction in fractures has not yet been demonstrated. Train at high intensity and under supervision for the best results.
Does vitamin D prevent bone fractures?
Studies show that vitamin D combined with calcium may offer a small benefit for older people with a deficiency. Vitamin D as a standalone supplement does not show that effect.
What do bone-loss medications (bisphosphonates) do, and are they safe?
Bisphosphonates reduce fractures and increase bone density in osteoporosis, and at high fracture risk can be used safely for up to ten years, provided that dental procedures are discussed with your doctor in advance.
Do people with darker skin have a higher risk of osteoporosis (bone loss)?
People with darker skin have a greater chance of vitamin D deficiency, but that does not automatically mean greater bone loss. Whether you are actually at risk depends strongly on your age, eating habits, and how often you spend time outdoors.
Does taking vitamin D help against cancer?
If you already have sufficient vitamin D in your blood, extra supplementation probably does not help against cancer. If you have a demonstrable deficiency, have it corrected, but do not count on this significantly lowering your cancer risk.
Do tanning beds give you vitamin D?
A sunbed can raise your vitamin D level, but only if the light also contains UV-B, and most commercial beds emit very little of it. Because sunbeds demonstrably increase the risk of skin cancer, a vitamin D supplement is the safer choice.