Last updated: October 2026
Most UK adults don’t need calcium supplements. The NHS says adults need 700mg of calcium a day, which a varied diet usually provides. A supplement makes sense if you eat little dairy or fortified food, or your GP advises one alongside osteoporosis treatment. Keep supplements to 1,500mg a day or less, and take 500mg or less at a time.
The short version: food first (a glass of milk, a matchbox of cheese or a 125g pot of yoghurt is about 200mg each), top up only the gap, choose calcium carbonate with meals or calcium citrate with or without food, split doses, get enough vitamin D, and keep calcium apart from iron, thyroid tablets and some antibiotics (ask your pharmacist about the gap). If you take osteoporosis medicine, follow your GP’s plan.
How much calcium do you need a day?
The NHS says adults need 700mg of calcium a day, and that you should be able to get it all from your diet. Calcium is needed for the maintenance of normal bones, and calcium contributes to normal muscle function and normal blood clotting.
Some groups are advised to aim higher, and UK sources don’t all agree, so treat this as a starting point for a chat with your GP or a dietitian:
| Who | Calcium a day | Source |
|---|---|---|
| Adults, including pregnancy | 700mg | NHS, Royal Osteoporosis Society |
| At risk of osteoporosis or taking an osteoporosis medicine | Around 1,000mg, if your doctor advises it | Royal Osteoporosis Society |
| Women after the menopause, men over 55 | 1,200mg | British Dietetic Association |
| Breastfeeding | 1,250mg | British Dietetic Association |
| Coeliac disease | 700mg (Coeliac UK); 1,000mg to 1,500mg (BDA) | Coeliac UK, British Dietetic Association |
| Inflammatory bowel disease while taking steroids | 800mg to 1,000mg | British Dietetic Association |
| Teenagers 11 to 18 | 1,000mg (boys), 800mg (girls) | Royal Osteoporosis Society |
The ROS says more than the recommended amount is unlikely to make bones stronger, and a calcium blood test can’t tell you whether your diet gives you enough.
Food first: calcium in everyday UK foods
Food is the NHS’s first choice, and 700mg is easier to reach than most people think. Approximate amounts per average portion, from the Royal Osteoporosis Society’s food chooser:
| Food | Portion | Calcium (approx.) |
|---|---|---|
| Milk (skimmed, semi or whole) | 1 glass (200ml) | 200mg |
| Fortified soya, oat or almond drink | 1 glass (200ml) | 200mg |
| Cheddar cheese | Small matchbox piece (35g) | 200mg |
| Yoghurt | 125g | 200mg |
| Porridge made with milk | 1 bowl (160g) | 200mg |
| Tinned sardines (with bones) | Half a tin (60g) | 200mg |
| Calcium-set tofu | Palm-size piece (100g) | 200mg |
| Kale, boiled | 4 heaped tablespoons (80g) | 200mg |
| White or wholemeal bread | 2 medium slices | 100mg |
| Almonds | 1 handful (30g) | 100mg |
| Broccoli, boiled | 3 tablespoons (80g) | 25mg |
Porridge with milk, a cheese sandwich and a yoghurt already add up to about 700mg. Low-fat dairy has as much calcium as full-fat, and bread counts because the NHS lists foods made with fortified flour as a source. Spinach contains calcium your body can’t absorb well, so don’t count it, and check plant drinks are fortified. The ROS says the fibre in high-fibre foods slightly lowers absorption, but not enough to matter. Many of the same foods appear in foods high in magnesium.
Who may need a calcium supplement?
The ROS says supplements are for topping up when food falls short. That most often means:
| Who | Why | What to ask your GP |
|---|---|---|
| Little or no dairy (vegan, dairy-free, lactose intolerant) | The NHS calls dairy an important source of calcium, and only fortified plant drinks match milk. | “Am I getting 700mg from food? Could a dietitian check my diet?” |
| Osteoporosis, or taking a bisphosphonate such as alendronic acid | The NHS says you may need more calcium, usually as supplements, often prescribed with vitamin D. The ROS suggests around 1,000mg a day in total. | “How much do I need on top of my diet, and when should I take it around my medicine?” |
| Coeliac disease | Gut damage before diagnosis stops calcium being absorbed, and the NHS says some people also need to avoid lactose for a while. | “Has my diet been assessed? Do I need a DEXA bone density scan?” |
| Crohn’s disease or ulcerative colitis | Crohn’s and Colitis UK says gut inflammation and steroids both reduce calcium absorption, and some people avoid dairy. | “Do my steroids affect my bones? Should I take calcium and vitamin D?” |
| After the menopause | The NHS says women lose bone rapidly in the first few years after the menopause, especially if it starts before 45. | “What is my fracture risk? Should I have a bone scan? Is HRT an option for me?” |
| Long-term steroid tablets | The NHS lists high-dose steroid tablets for more than 3 months as a risk factor for osteoporosis. | “Do I need bone protection while I’m on these?” |
For the bigger picture after 40, see supplements for women over 40, perimenopause symptoms and the best supplements for menopause. If you’re prescribed calcium, don’t stop without telling your doctor: the ROS warns that stopping when your diet is short can harm your bones.
Calcium carbonate vs calcium citrate
The figure that matters on a label is elemental calcium, the amount of calcium itself rather than the weight of the whole compound. The two main forms differ in strength and in how you take them:
| Calcium carbonate | Calcium citrate | |
|---|---|---|
| Elemental calcium | About 40% (1,250mg gives about 500mg calcium) | About 21%, so more or bigger tablets |
| How to take it | With a meal, as it needs stomach acid | With or without food |
| Best for | Most people; usually the cheaper option | Low stomach acid, or taking acid-reducing medicines such as omeprazole |
| Gut side effects | More likely to cause constipation | Often easier to digest |
The ROS says both forms are good for your bones. Citrate was absorbed slightly better in a small study, but carbonate with food works well for most people. Gluconate and lactate contain less calcium, and MedlinePlus advises avoiding unrefined oyster shell, bone meal and dolomite, which may contain lead. Prescribed packs often state the compound, so the ROS suggests checking the leaflet for the “available” calcium. If you take a multivitamin, add its calcium to your total.
How to take calcium supplements
- Split the dose. Take 500mg or less at a time. Absorption rises up to about 500mg and barely improves above it, and smaller doses cause less wind, bloating and constipation.
- Carbonate with meals. Citrate can go with or without food.
- Count antacids and multivitamins. Many indigestion remedies are calcium carbonate. Stay within 1,500mg a day from supplements in total.
Medicines to keep apart from calcium
Calcium binds to some medicines in the gut. Always tell your pharmacist you take it, and ask about the gap you need:
- Bisphosphonates such as alendronic acid: take the medicine on an empty stomach with plain water, at least 30 minutes before breakfast or anything else. The NHS says prescribed calcium and vitamin D are taken at a different time of day.
- Levothyroxine: the NHS lists calcium supplements among the things that don’t mix well with it. In a study of 20 people, 1,200mg of calcium carbonate taken with levothyroxine lowered thyroid hormone levels. Ask your pharmacist how far apart to take them. More in underactive thyroid symptoms.
- Iron tablets: the NHS says calcium can reduce the effect of ferrous sulfate, and advises a 2 hour gap from dairy. See iron tablets.
- Some antibiotics: leave at least 2 hours between calcium supplements and ciprofloxacin, says the NHS. Check the leaflet for any antibiotic you’re given.
- Zinc and magnesium: large doses of calcium can reduce how much you absorb, so take them at different times. See zinc.
Calcium and vitamin D
Calcium and vitamin D work as a pair. Vitamin D contributes to normal absorption/utilisation of calcium and phosphorus, and vitamin D contributes to normal blood calcium levels. That’s why calcium for osteoporosis is often prescribed together with vitamin D, and some calcium supplements already contain it.
The NHS advises all adults to consider a daily 10 microgram (400 IU) vitamin D supplement from October to March, when UK sunlight is too weak, and all year round if you rarely get outside or cover your skin. If your calcium tablet already contains vitamin D, count it towards that 10 micrograms. Our guides cover vitamin D in winter, the best time to take vitamin D and signs of vitamin D deficiency.
Side effects, kidney stones and the heart debate
Side effects and upper limit
The ROS says calcium supplements can cause constipation, diarrhoea or feeling sick, and a different form may suit you better. MedlinePlus suggests more fluids and fibre first; see also magnesium for constipation. The NHS says 1,500mg or less a day from supplements is unlikely to cause harm, while higher doses could cause stomach pain and diarrhoea, and the ROS adds kidney stones.
Kidney stones
In the Women’s Health Initiative trial of 36,282 postmenopausal women, 1,000mg of calcium (as calcium carbonate) with 400 IU of vitamin D daily for about 7 years raised the risk of kidney stones by 17%. Calcium from food is different: the NHS advice for preventing kidney stones includes making sure you get enough calcium in your diet. If you’ve had kidney stones or have kidney disease, speak to your GP before taking a supplement.
Do calcium supplements affect your heart?
This is a genuine debate, so here are both sides:
- The worry: a 2010 meta-analysis of 15 trials found calcium supplements without vitamin D were linked to about a 27% higher rate of heart attacks. A 2011 reanalysis that included the Women’s Health Initiative found a similar rise, 24%, with or without vitamin D.
- The reassurance: a 2015 meta-analysis of 18 trials in 63,563 mostly older women found no increase in coronary heart disease or deaths. A 2016 review concluded that calcium within upper intake levels is not linked to heart disease in generally healthy adults.
- UK view: the ROS says there isn’t enough evidence to prove calcium supplements raise heart attack risk, and the BDA notes the Department of Health didn’t change prescribing advice.
The benefit side is modest too. A 2015 review found supplements cut total fractures by about 11%, but trials at the lowest risk of bias showed no effect. The sensible middle ground: get calcium from food where you can, use a supplement only for the gap, and don’t go over 1,500mg a day.
Calcium vs magnesium
Both minerals are in bone, and magnesium contributes to the maintenance of normal bones. They do different jobs, though, and you don’t need to match them to a fixed ratio. Whether to take them together, timing and the ratio myth are covered in magnesium and calcium, and the bone research in magnesium and bone health.
Does Evopure sell calcium?
No. Evopure doesn’t make a calcium supplement, and for most people food is the better source. If your GP prescribes calcium, take what they recommend.
If you take our Magnesium Glycinate Sleep Complex, an evening drink with magnesium bisglycinate and citrate, take calcium at a different time of day. On regular medicine? Tell your pharmacist: the NHS asks people on alendronic acid to mention magnesium supplements, for example. Magnesium contributes to a reduction of tiredness and fatigue.
For vitamin D, a plain 10 microgram supplement is the simplest choice. If you already use CBD oil, our Evolabs Mint CBD Oil adds 5 micrograms of vegan vitamin D3 per half pipette, and vitamin D contributes to the maintenance of normal bones. CBD isn’t a source of calcium or a treatment for bones. The FSA’s 10mg a day figure is precautionary advice rather than a legal limit, set while longer-term safety research continues. At Evopure we think it is a very cautious figure, and many adults use more. If you go above it, increase slowly, and check with your GP or pharmacist first if you take any medication.
Our products are for adults only, and we don’t recommend our products during pregnancy or breastfeeding.
FAQs
Do I need to take calcium supplements?
Most adults don’t. The NHS says 700mg a day, which a varied diet usually provides. A supplement can help if you eat little dairy or fortified food, or your GP advises one with osteoporosis treatment.
Which is better, calcium carbonate or calcium citrate?
Both are good for bones. Carbonate has more calcium per tablet and should be taken with meals. Citrate can be taken with or without food and suits people with low stomach acid or on acid-reducing medicines.
What is the best time to take calcium?
With meals if it is calcium carbonate, in doses of 500mg or less. Keep it apart from iron, levothyroxine and some antibiotics (ask your pharmacist about the gap), and take bisphosphonates first on an empty stomach.
Should I take calcium with vitamin D?
You need enough vitamin D to absorb calcium. The NHS advises all adults to consider 10 micrograms a day from October to March. Some calcium supplements already contain vitamin D.
How much calcium should a woman over 50 have?
The NHS says 700mg a day for all adults. The British Dietetic Association suggests 1,200mg after the menopause, and the ROS around 1,000mg if you’re at risk of osteoporosis or on treatment. Ask your GP which applies to you.
Are calcium supplements bad for your heart?
The evidence is mixed. Some analyses linked supplements to more heart attacks, while larger later reviews found no clear increase. UK bodies have not changed their advice. Food first and no more than 1,500mg a day from supplements is sensible.
Do calcium supplements cause constipation?
They can, especially calcium carbonate. Drink more fluids, eat more fibre and split your dose. If it continues, ask your pharmacist about switching to calcium citrate.
Sources
- NHS. Vitamins and minerals: calcium.
- NHS. Osteoporosis: treatment, overview and prevention.
- NHS. Vitamin D.
- NHS medicines: alendronic acid, levothyroxine, ferrous sulfate and ciprofloxacin.
- NHS. Kidney stones and coeliac disease complications.
- Royal Osteoporosis Society. Calcium and calcium-rich food chooser (reviewed July 2025).
- British Dietetic Association. Calcium food fact sheet (January 2026).
- Coeliac UK. Osteoporosis.
- Crohn’s and Colitis UK. Bones.
- GB nutrition and health claims (NHC) register. gov.uk.
- MedlinePlus. Calcium supplements.
- HealthLink BC. Calcium supplements.
- Straub DA. Calcium supplementation in clinical practice: a review of forms, doses, and indications. Nutr Clin Pract, 2007. PMID 17507729.
- Harvey JA et al. Dose dependency of calcium absorption: calcium carbonate and calcium citrate. J Bone Miner Res, 1988. PMID 3213620.
- Singh N et al. Effect of calcium carbonate on the absorption of levothyroxine. JAMA, 2000. PMID 10838651.
- Jackson RD et al. Calcium plus vitamin D supplementation and the risk of fractures. NEJM, 2006. PMID 16481635.
- Bolland MJ et al. Calcium supplements and risk of myocardial infarction: meta-analysis. BMJ, 2010. PMID 20671013.
- Bolland MJ et al. Calcium supplements with or without vitamin D and cardiovascular events. BMJ, 2011. PMID 21505219.
- Lewis JR et al. Calcium supplementation and coronary heart disease in postmenopausal women: meta-analysis. J Bone Miner Res, 2015. PMID 25042841.
- Chung M et al. Calcium intake and cardiovascular disease risk. Ann Intern Med, 2016. PMID 27776363.
- Bolland MJ et al. Calcium intake and risk of fracture: systematic review. BMJ, 2015. PMID 26420387.
This guide is general information, not medical advice. Always follow your GP’s or pharmacist’s advice and read the leaflet with any medicine. Evopure makes the Magnesium Glycinate Sleep Complex and Evolabs Mint CBD Oil with vitamin D3, and does not sell calcium supplements.
