Calcium: functions, foods, deficiency and supplements

Find out all about calcium, including what it does, how much you need, where to find it and who might need to supplement their diet

Overview of calcium

What is calcium and what does it do?

Calcium is a mineral that’s essential for all living organisms. It’s the most abundant mineral in our body¹ and is needed for:²

• maintaining healthy bones and teeth
• normal blood clotting
• controlling muscle contractions, including heartbeat
• healthy digestion

Calcium is found in milk, cheese and dairy foods, dark green vegetables and nuts. Most people will get all the calcium they need from their diet,³ but vegans or those who don’t eat dairy may be lacking.⁴ A calcium deficiency can lead to rickets when you’re young, and osteoporosis or brittle bone disease later in life.⁵

Functions of calcium

What does calcium do in the body?

Around 99% of the calcium in our bodies is stored in our bones and teeth.⁶ Calcium helps our bones to grow strong until the age of 20-25, when bone density reaches its peak. After the age of about 35 years, the amount of bone tissue we have naturally starts to decrease, but calcium can help to maintain our bone density and slow down bone loss.⁷ Calcium also enables our blood to clot normally and regulates our muscle contractions, including our heartbeat.⁸ We lose calcium everyday via our skin, nails, sweat, urine and faeces. Our bodies cannot make calcium, so we need to get enough from our diets. If we don’t, our body can start leaching it from our bones. This is fine once in a while, but if it happens on a regular basis, it could eventually lead to weak bones.⁹ Vitamin D is essential to help our body absorb calcium properly from food. A calcium deficiency could even occur due to low vitamin D levels.¹⁰ The government recommends everyone over the age of one gets 10mcg of vitamin D a day.¹¹

How much calcium do I need?

The reference nutrient intake (RNI) for adults is 700mg a day – about the amount found in a glass of milk and a small portion of whitebait¹² – but some groups may need more, such as breast-feeding women, post-menopausal women and those with coeliac disease.¹³

How much calcium do children need?

Children need increasing amounts of calcium while growing,¹⁴ especially during puberty, to build bone density.

• 0-12 months – 525mg daily
• 1-3 – 350mg daily
• 4-6 – 450mg daily
• 7-10 – 550mg daily
• 11-18 – boys 1000mg, girls 800mg daily

Calcium foods

Which foods are the best sources of calcium?

The best food sources¹⁵ of calcium include:

• a glass of malted milk – this contains your RNI in one glass
• fish with soft bones, like sardines or whitebait
• a glass of regular, semi-skimmed or skimmed milk
• a small portion of cottage cheese
• a small pot of yoghurt

The best plant-based sources¹⁶ of calcium include:

• calcium-enriched plant milks
• green leafy veg, such as kale
• dried figs
• nuts and seeds, including almonds
• white or brown bread – white and brown flour is fortified in the UK

Calcium deficiency

Who is most at risk of calcium deficiency?

You are more at risk of a calcium deficiency¹⁷ if you:

• are on a cow’s milk- or lactose-free diet
• have coeliac disease, as you may not be able to absorb nutrients properly
• are breast-feeding
• have been through the menopause – oestrogen helps protect bones, so declining levels can lead to osteoporosis

Children are at the greatest risk of developing rickets between six and 36 months because they experience rapid growth during this time, which increases their need for calcium and vitamin D. Rickets leads to soft bones and stunted growth.¹⁸

What are the symptoms of a calcium deficiency?

Symptoms of a calcium deficiency include:¹⁹

• muscle aches and cramps
• extreme fatigue
• dry, itchy skin
• brittle nails
• tooth loss
• more fractures due to weak bones

What happens if I consume too much calcium?

Getting too much calcium – more than 1,500mg a day – can lead to stomach pain and diarrhoea,²⁰ and could even lead to developing kidney stones.²¹

Calcium supplements

When should I take calcium supplements?

You should be able to get all the calcium you need from your daily diet. But if you’re vegan, going through the menopause, or have been diagnosed with osteoporosis, you may want to consider a supplement.²²

 Should children take a calcium supplement?

Children eating a healthy, balanced diet should be getting all the calcium they need.²³ If you’re worried they’re not, talk to your GP before giving them supplements.

Should women take a calcium supplement during pregnancy?

Pregnant women do not need calcium supplements as they can get all the calcium they need from their diet. However, all adults – including pregnant and breastfeeding women – need 10mcg of vitamin D a day, so should consider taking a supplement.²⁴

What are the potential benefits of taking a calcium supplement?

After menopause, women lose more bone mass due to a decline in oestrogen. But a 2014 review of studies concluded that calcium supplements could help reduce bone loss in elderly and post-menopausal women.²⁵ It’s also thought that a low-calcium intake could lead to a higher BMI. Chinese researchers found overweight people with low calcium levels who were given combined calcium and vitamin D supplements, lost more body fat on a calorie-controlled diet than those who didn’t take the supplement.²⁶ Shop Minerals Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies. Written by Nic Hopkirk on November 28, 2018 Reviewed by dietitian and nutritionist Azmina Govindji on December 19, 2018 Sources  1. Beto, J. The Role of Calcium in Human Ageing. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4337919/ 2. European Commission. EU Register on nutrition and health claims. Available from: http://ec.europa.eu/food/safety/labelling_nutrition/claims/register/public/?event=register.home 3. NHS. Calcium. Available from: https://www.nhs.uk/conditions/vitamins-and-minerals/calcium/ 4. British Nutrition Foundation. Dietary calcium and health. Available from: https://www.nutrition.org.uk/attachments/105_Dietary%20calcium%20and%20health.pdf 5. April Khan and Ana Gotter. Hypocalcemia (Calcium Deficiency Disease). Healthline.com. Available from: https://www.healthline.com/health/calcium-deficiency-disease 6. Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Available from: https://www.ncbi.nlm.nih.gov/books/NBK109827/ 7. National Osteoporosis Society. What is osteoporosis? https://nos.org.uk/about-osteoporosis/what-is-osteoporosis/ 8. As Source 3 9. National Osteoporosis Foundation. Calcium/Vitamin D. Available from: https://www.nof.org/patients/treatment/calciumvitamin-d/ 10. British Nutrition Foundation. Calcium. Available from: https://www.nutrition.org.uk/nutritionscience/nutrients-food-and-ingredients/minerals-and-trace-elements.html?start=3 11. NHS. Vitamin D. Available from: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ 12. The Association of UK Dieticians. Calcium Food Fact Sheet. Available from: https://www.bda.uk.com/foodfacts/Calcium.pdf 13. As above 14. NHS. Royal Surrey County Hospital. Calcium for infants and children. Available from: https://www.royalsurrey.nhs.uk/wp-content/uploads/2017/11/PIN1297_Calcium_for_infants_and_children_w.pdf 15. As Source 12 16. British Nutrition Foundation. Dairy and non-dairy sources of calcium. https://www.nutrition.org.uk/attachments/article/874/Calcium%20counts_final_20.08.18.pdf 17. Kerri-Ann Jennings, MS, RD. Calcium Supplements: Should You Take Them? Healthline.com. Available from: https://www.healthline.com/nutrition/calcium-supplements 18. Jacquelyn Cafasso. Rickets. Healthline.com. Available from: https://www.healthline.com/health/rickets 19. April Khan and Ana Gotter. Healthline. Hypocalcemia (Calcium Deficiency Disease). Available from: https://www.healthline.com/health/calcium-deficiency-disease 20. As Source 3 21. As Source 17 22. As Source 19 23. As Source 14 24. As Source 11 25. Lamy O, Burckhardt, P. Calcium revisited: part II calcium supplements and their effects. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4189255/ 26. Zhu W, et al. Calcium plus vitamin D3 supplementation facilitated fat loss in overweight and obese college students with very-low calcium consumption: a randomized controlled trial. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23297844