Calcium is essential for strong teeth and bones, and most people can get all the calcium they need from eating a balanced diet. But it is important to get the balance right — too little calcium can put you at greater risk of bone conditions such as osteoporosis, while taking too much calcium in the form of supplements can also be harmful. We asked the National Osteoporosis Society to explain who might benefit from a calcium supplement and when to see your doctor.


Who is more at risk of calcium deficiency?

If you make sudden changes to your diet or are unable to eat high-calcium food groups such as dairy, you will need to make careful food choices to ensure you get adequate calcium. However, it should be easy to get enough calcium from a range of different food sources.

See our guide on the best calcium-rich foods to discover how much calcium you need and how to achieve this through your diet.

Pouring milk into a glass

Are there symptoms that can indicate whether I have calcium deficiency?

It’s very unlikely you will present with severe calcium deficiency symptoms as a result of a limited diet. There is also no simple way to know or test to see if you are getting enough. The best approach is to ensure an adequate intake through a balanced diet and talk to your doctor if you are concerned.

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Should people at risk of calcium deficiency consider taking a calcium supplement?

If you are concerned that you are not getting enough calcium in your diet you should discuss this with your doctor or GP. Some medical conditions mean you may need tailored advice as to whether you should take a calcium supplement and how much you need.

If your doctor agrees that a supplement will be beneficial for you, they are likely to try to calculate roughly how much you are getting from food and drink in a day and work out how much supplement you may need. One or two tablets a day are usually recommended, if necessary, along with topping up the amount that you get from your food and drink. To understand how much calcium you are getting in each dose, look at how much ‘elemental’ calcium (the actual amount of calcium) the supplement provides. For instance, 1250 mg of calcium carbonate provides 500mg calcium. Supplements vary widely but most will provide between 300mg-1000mg of elemental calcium.

Can you take too much calcium, and what are the risks of this?

If you are prescribed a calcium supplement then it will usually be 500mg – 1200mg a day. Taking more than about 2,500mg of calcium a day on a regular basis could lead to medical problems including a high level of calcium in the blood, known as milk alkali syndrome. Too much calcium might also interfere with the absorption of other minerals such as iron and magnesium.

There are some medical conditions that cause high blood calcium levels (the body stops regulating levels in the blood in the normal way) which can make you very unwell and in this situation, your doctor would advise you not to take supplements.

If you are concerned that you are at risk of taking too much calcium you should discuss this with your doctor or GP.

Calcium supplements on a page of text about calcium

I’ve heard that calcium supplements may be linked to heart attacks. Is this true?

There haven’t been any research studies properly designed to answer this question. For the majority of people, it makes sense to get calcium from healthy balanced eating as far as possible and only supplement if necessary (and if approved by your doctor) to top up to recommended levels.

A high calcium intake from food and drink doesn’t seem to increase heart attack risks. Some research studies have suggested you may have an increased risk of heart attack if you take high doses of a calcium supplement alone, or calcium and vitamin D together, although the incidence of heart attack was still low. It is still unclear exactly what is causing these findings, although some researchers suggest one reason could be through a slow process of calcium being laid down in your blood vessels (called 'calcification') and because blood calcium levels rise briefly after taking supplements.

There is some uncertainty about the conclusions of these studies as other research has found that taking calcium and vitamin D supplements does not increase your heart attack or stroke risk.

The UK drugs regulatory organisation MHRA looked at the research findings and recommended that doctors still need to ensure you are getting sufficient calcium especially if you are taking osteoporosis drug treatments. The guidance says that doctors should continue to prescribe calcium supplements when necessary.

If you are concerned about taking your prescribed calcium supplements because of the link with heart disease you should discuss this with your doctor.

Now read...

The best calcium-rich foods
What is osteoporosis and what affects bone density?
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This article was published on 10 May 2017.

The information was supplied by Sarah Leyland, Osteoporosis Nurse Consultant at the National Osteoporosis Society in collaboration with the NOS's expert clinical and scientific advisors. It has been reviewed by Professor Susan Lanham New, Professor of Nutrition at the University of Surrey.

The National Osteoporosis Society are a UK-wide charity dedicated to ending the pain and suffering caused by osteoporosis. You can find out more information by visiting their website.


All health content on is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.

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