Also in Patient Information Leaflets:
How does calcium and vitamin D work with my treatment?
In the body, calcium works together with osteoporosis treatments to fill holes in old worn out bone made by cells called osteoclasts. Working along side bone building cells called osteoblasts, these holes are closed over. This constant process of renewal is called bone turnover. Vitamin D controls the absorption of calcium from the gut.
Do I need a calcium and vitamin D supplement with my osteoporosis treatment?
In the studies looking at the effect of osteoporosis treatments on reducing the rate of fractures in post menopausal women, it was ensured that the people recruited into the trials were also having enough calcium (with or without vitamin D). Therefore, it cannot be assumed that the osteoporosis treatments will achieve a similar level of effect on the bones to that seen in the trials without ensuring that people have sufficient levels of calcium.
Of course, many people will not need a calcium and vitamin D supplement. If you already get all the calcium that you need from your diet and vitamin D from exposure to sunshine, then a supplement will not be necessary. There is no evidence to suggest that taking more than the required level (see below) will provide any extra benefit for your bones.
How much calcium and vitamin D do I need?
The Government's advisors on nutrition (Scientific Advisory Committee on Nutrition) have set levels of dietary calcium intake or reference nutrition intake (RNI), of which 700 mg is sufficient to meet the daily requirements for 95% of the adult population. These advisors also recommend that 400 mg is the lower reference nutrition intake (LRNI) or the lowest amount of calcium required for maintaining a healthy adult skeleton.
If you have osteoporosis, the National Osteoporosis Society's medical advisors recommend an overall calcium intake of 1200 mg per day. This is particularly important for those people who receive glucocorticoid (steroid) tablets who may have decreased calcium absorption and for those people with malabsorption problems such as Crohn's or coeliac disease.
The daily recommended intake of vitamin D is 10 micrograms (mcg) or this is sometimes also expressed as international units (iu). Ten mcg = 400 iu. It is thought that a substantial proportion of all people with osteoporosis have a calcium intake lower than 700 mg per day and many also have low circulating levels of vitamin D.
Can I get enough calcium from my diet?
There are many different food sources of calcium. Please refer to our Information Sheet on calcium rich foods for lists of calcium content calculated in a 100 gram portion of food. This may be downloaded from our Website on the following hyperlink http://www.nos.org.uk/public.asp or
by contacting the NOS on 01761 471771.
Many people will struggle to achieve all the calcium they require from their diet. So if you are taking a treatment for osteoporosis and have a low dietary calcium intake, the use of a calcium and vitamin D supplement will ensure that you are getting enough.
As doctors cannot always assume that a person's dietary intake of calcium is sufficient, they will often prescribe a calcium and vitamin D supplement.
So what about vitamin D?
About 90% of the recommended daily intake of vitamin D is obtained through the action of sunlight on the skin. Around 20 - 30 minutes per day with your face, arms and legs in the sun is
thought to be sufficient. The remaining 10% comes from the diet. Useful food sources of vitamin D are margarine which is fortified and oily fish such as sardines and herrings.
Elderly people are less able to make and use vitamin D efficiently, especially if they are housebound and have little exposure to sunlight. A supplement which combines both calcium and vitamin D is therefore recommended.
Do any of the osteoporosis treatments already contain calcium?
One of the established osteoporosis treatments, cyclical etidronate (Didronel PMO) comes with a supply of calcium in the form of Cacit, the manufacturers own brand of calcium citrate 500 mg.
If your doctor is concerned that you may need vitamin D as well your cyclical etidronate, a separate vitamin D product may be prescribed.
Could I just take calcium and vitamin D as a treatment for my osteoporosis?
Calcium and vitamin D can be used to help prevent hip fractures in frail older people who live in residential or nursing homes. The two large trials that showed a reduction in the risk of hip or other fractures, used between 1000 to 1200 mg of calcium and 700 to 800 iu of vitamin D per day. If you have already suffered a fracture, it is likely that your doctor will want to consider a stronger treatment than just calcium and vitamin D.
For people under 75, calcium and vitamin D is not generally considered as a treatment option but can be used as part of a lifestyle approach to maintaining bone health. A combination of
weight bearing exercise, a well balanced diet (including foods from a mixture of nutrients including protein and carbohydrates, fruit, vegetables and dairy products), not smoking, moderate alcohol intake and the use of a calcium supplement can all enhance the effectiveness of your osteoporosis medication.
If I need a supplement, which supplement should I choose?
There are many products available, some of which are available on prescription from your GP. Others are sold over the counter at the pharmacy, health food store or supermarket. If you are considering an over the counter supplement, it is advisable to discuss this with an in-store or high street pharmacist beforehand, to check for any reason why you should not proceed.
Can I have too much calcium?
There is an upper limit to the amount of calcium that can be taken safely. It is recommended that you do not exceed 2000 - 2500 mg of calcium per day included in your food, drink and supplements. Consistently exceeding the upper limit may increase your risk of medical problems including a high level of calcium in the blood (milk alkali syndrome) and may interfere with the absorption of other minerals such as iron.
If you have a history of kidney stones, consuming a diet rich in calcium will not increase your risk of further stone formation. Interestingly, most renal doctors do not restrict calcium intake for their patients these days.
Can I have too much vitamin D?
Although there are some studies looking at the effects of a high intake of vitamin D and toxicity, there is not yet enough information to specifically identify an upper safe limit. Therefore it seems sensible to keep to the recommended daily intake levels.
Are there any particular instructions as to how and when to take my supplement?
Remember not to take your calcium supplement at the same time of day as your strontium ranelate or bisphosphonate (alendronate, risedronate and cyclical etidronate) osteoporosis treatment, as calcium will prevent the absorption of these drugs.
Splitting the dose which is mostly two 500 mg tablets is advisable, as the gut would not be able to absorb 1000 mg all at once. To maximise the absorption of your calcium tablet, take it at meal times with or after food. You may also need to take iron tablets for other health reasons. If so, avoid taking calcium at the same time by staggering the tablets throughout the day. This will ensure that both minerals are fully absorbed.
To obtain other NOS publications and Information Sheets, go to www.nos.org.uk or telephone 01761 471771.
To contact the NOS osteoporosis nurses, telephone the NOS Helpline on 0845 450 0230 or e-mail them on firstname.lastname@example.org
For regular updates on osteoporosis, join the NOS on-line today www.nos.org.uk
or telephone 01761 473117 / 473119 to speak to one of our Membership Coordinators.