Calcium supplements
We know that we need calcium for strong, healthy, bones. If you have, or are at risk of, osteoporosis, taking calcium supplements to give your bones some extra oomph, as many of us do, seems sensible. However, according to the results of a new study it may not be a good idea for all of us.
The study, published on bmj.com, was carried out by scientists in New Zealand, Aberdeen and the USA. It looked at the results of 11 different studies, involving 12,000 patients in total. The aim was to find out what effect, if any, the supplements had on the risk of heart attack. The results showed that taking calcium supplements was associated with about a 30 percent increased risk. The National Osteoporosis Society explains that this may be caused by a slow build-up of calcium in our blood vessels (known as calcification).
However the potential risk doesn’t affect everyone. The study found that it applied to older women taking supplements that pushed their calcium levels above the recommended daily intake. And that, it seems, is the crux of the problem. Taking in too much calcium may raise your risk.
How much is too much?
According to the National Osteoporosis Society, we should take in around 700 mgs of calcium a day. This is an average figure. If you don’t consume this much in one day, it doesn’t matter as long as you catch up another day. Regularly taking supplements may cause problems if you’re already getting enough from the food you eat. This is particularly so because calcium from foods such as dairy products has a much smaller effect on our serum calcium levels than taking calcium supplements.
Dr Claire Bowring of the National Osteoporosis Society said: "We’ve always recommended that people should aim to get the calcium that they need from their diet to help build stronger bones. If you get all of the calcium that you need from your diet, and adequate vitamin D from exposure to sunshine, then a supplement will not be necessary.
"However, if you are unable to get enough calcium from your diet, supplementation may be warranted but it needs to be done with consideration. You need to assess how much calcium you are already getting and supplement to top it up to recommended levels. Boosting calcium levels beyond this has no extra benefit for bones."
It’s important to bear in mind that this study looked at participants who took calcium only. If you take a calcium and vitamin D supplement, the results may not apply to you. As Judy O’Sullivan, Senior Cardiac Nurse at the British Heart Foundation points out, "Anyone who has been advised by their doctor to take calcium supplements shouldn’t stop because of this research alone."
How do you know if you are getting enough calcium from your diet? Good sources are dairy products, including cheese, milk and yogurt, green leafy vegetables, such as broccoli and cabbage, and tinned fish with bones, such as sardines.
The National Osteoporosis Society website has a useful leaflet called Healthy bones – facts about food. It includes information on the amount of calcium you can get from different foods. For instance, 100 mls of skimmed milk contains 122 mg of calcium, 100 grams of Cheddar cheese contains 739mg of calcium, 100g of sardines in oil contains 430mg of calcium and 100g of watercress contains 170mg of calcium.
If you are taking calcium supplements and are concerned about whether they are right for you, talk to your GP.
First published July 30, 2010
Useful websites
British Heart Foundation - www.bhf.org.uk
National Osteoporosis Society - www.nos.org.uk