Calcium Supplements: Who Actually Needs One

Approximate calcium content of everyday portions:

• Milk, 200ml glass: about 240mg
• Cheddar, a 30g matchbox: about 220mg
• Yoghurt, 150g pot: about 200mg
• Tinned sardines with the bones, half a tin: about 250mg
• Fortified plant milk, 200ml: about 240mg (check the label, since unfortified versions have almost none)
• Tofu set with calcium sulphate, 100g: 200 to 350mg
• Kale, 80g cooked: about 120mg
• Two slices of white bread: about 90mg, since UK white and brown flour is fortified by law
• Tinned baked beans, half a tin: about 60mg
• Dried figs, four: about 100mg

A glass of milk, a pot of yoghurt and a small piece of cheese gets an adult to 700mg before anything else on the list is counted. That is why the food-first position is the standard one: the target is genuinely reachable for most people.

The Royal Osteoporosis Society puts it the same way, advising that most people can get all the calcium their bones need from food, with supplements used to top up a shortfall. Their site has a calculator worth ten minutes of your time before you buy anything.

The people for whom a supplement earns its place:

• Anyone who avoids dairy without replacing it with calcium-fortified alternatives. This is the largest group by some margin, and it includes people who switched to plant milks and did not check whether the one they bought is fortified.
• People prescribed treatment for osteoporosis. Most bone medications are trialled and prescribed on the assumption of adequate calcium and vitamin D, and prescribers often supply both alongside.
• People with conditions or surgery affecting absorption, including coeliac disease, inflammatory bowel disease and bariatric surgery.
• People with a poor appetite or a restricted diet, which frequently means older adults living alone or recovering from illness.
• People on long-term corticosteroids, which reduce bone density.

If none of those apply and your food intake is already near 700mg, a supplement is adding a number that was already reached. Add up a normal day first, using the figures above.

Two concerns come up, and the evidence on both is genuinely mixed rather than settled.

Heart disease. Some meta-analyses of trial adverse-event data have reported an increase in heart attack risk of roughly 10 to 20% with calcium supplements, while calcium from food shows no such association. Other analyses and later reviews have found no significant effect. The Royal Osteoporosis Society's position is that there is not enough evidence to conclude supplements raise the risk. The honest summary is that a modest possible signal exists for supplements and not for food, which is one more argument for the food-first approach and for not exceeding the amount you actually need.

Kidney stones. High supplemental calcium has been associated with an increased risk of stones in some large studies, while high dietary calcium has been associated with a lower risk, probably because calcium eaten with a meal binds oxalate in the gut. Anyone with a history of kidney stones should raise this with their GP before taking one.

Practical implications: take the amount that fills your gap rather than a large round number, split doses of more than 500mg across the day since absorption is better in smaller amounts, and take it with food.

Calcium is the raw material for bone. Mechanical load is the instruction to use it. Supplying more material without the instruction changes very little, which is why calcium supplementation alone has a small effect on bone density and a weak effect on fracture risk in the general population.

The stimulus bone responds to is force: resistance training heavy enough to be demanding, and impact through the legs and spine. Swimming and cycling are excellent for many things and near-useless for bone, because the skeleton is largely unloaded in both.

The second half of fracture prevention is not falling over, which is a matter of leg strength, balance and confidence rather than of nutrition. Our guide to falls prevention covers the programmes with evidence behind them, and rehab for seniors covers how that work is built up safely.

Buxted Park is where a good number of people in this area do their walking, and a lap of it is a genuinely useful thing for the heart, the head and the knees. What it does for the hip and spine bone density of someone who has just been told they have osteopenia is close to nothing, and that surprises people who have been walking daily precisely because they were told to look after their bones.

The reason sits in how bone works. It remodels in response to strain, and strain means loads meaningfully heavier or faster than the ones the skeleton already handles every day. Walking on the flat is a load the body has been managing since childhood. What changes bone is a heavy carry, a loaded squat or step-up, a hop where hopping is safe, and enough repetition over months for the remodelling to happen. In the Uckfield clinic, the calcium question and the loading question nearly always arrive together, and the second one is the one that has been left out.

If you want a loading programme built for your bone density, your joints and what you can currently tolerate, consider checking our 1:1 rehab and strength training sessions are set up for exactly that.

How much calcium do I need a day?
700mg for UK adults aged 19 to 64. People at risk of osteoporosis or on treatment for it are often advised to aim for about 1,000mg.

Do I need a calcium supplement?
Only if your diet falls short. Add up a normal day first: a glass of milk, a yoghurt and a small piece of cheese together reach 700mg. Supplements matter most for people avoiding dairy without fortified alternatives, and for those on osteoporosis treatment.

Are calcium supplements bad for your heart?
The evidence is mixed. Some analyses report a modest increase in heart attack risk with supplements and none with dietary calcium; others find no effect. The Royal Osteoporosis Society considers the evidence insufficient to conclude there is a risk.

When is the best time to take calcium?
With food, and split into doses of 500mg or less if you are taking more than that, since absorption drops as the single dose rises.

Do I need vitamin D with calcium?
Vitamin D is required to absorb calcium properly, and UK sunlight cannot make it between October and March. The NHS advises considering 10 micrograms daily through autumn and winter.

Will calcium stop me breaking a bone?
On its own it does very little. Bone strengthens in response to mechanical load, and most fractures follow a fall, so strength and balance work carries more of the protection than any supplement does.