THE DUCHESS of Cornwall’s first public engagement, when still Mrs Camilla Parker Bowles, was at a meeting of the National Osteoporosis Society. Her mother and grandmother suffered from osteoporosis and it is said to have contributed to her mother’s death. Over the past few years the Duchess’s concern has helped to keep this problem in the news.

Osteoporosis was in the news again last week following a report in The Lancet on the value of calcium and vitamin D supplements in its prevention. Unfortunately, although the results of the Lancet trial were widely reported, they were to some extent misrepresented. Another study, also reported last week (in the BMJ), investigated the effect of calcium and vitamin D on a different group of elderly patients.

At first sight the Duchess doesn’t appear to be the classic osteoporotic type. The person most at risk is a post-menopausal woman, especially if she has had an early menopause. She is likely to be thin, with a family history of proven osteoporosis or a fractured hip, and to have a small frame. It is likely that she takes little weight-bearing exercise. When the condition is becoming clinically obvious the first symptoms — other than an unexpected fracture after a trivial fall — are loss of height, back pain and difficulty in straightening up.

Fortunately, the Duchess, well known as a keen horsewoman, is often pictured riding and therefore presumably takes a reasonable amount of exercise. The only certain way of making a diagnosis is by bone scanning, but unfortunately the waiting list for this is lengthy.

Bone strength is dependent on two principal factors: bone density and bone quality. The loss of bone density in women starts before the menopause at about the age of 35, or even earlier if a woman is anorexic, otherwise under-nourished or over-exercised (too much exercise when young can be as damaging to the bone as too little). The onset of osteoporosis is insidious and so may be missed, but its effects accelerate once oestrogen levels fall at the menopause. Men develop osteoporosis too, but it is only rarely a problem before they are 70. Bone strength is under-investigated in men.

The Lancet trial was an extensive one involving more than 21 centres and 15,000 patients. The results were concerned only with the effect of calcium and vitamin supplements, without any other additional treatment, on people over 70 who had already had one fracture. The fracture had followed minimal trauma and it was assumed that in part it was the result of osteoporosis. This trial wasn’t investigating the effect of calcium and vitamin supplements on those who hadn’t yet developed evidence of osteoporosis, regardless of lifestyle.

The important message conveyed by these results wasn’t that calcium and vitamin D supplements weren’t needed, but that they were inadequate to treat established, or predicted, osteoporosis, and that they needed to be combined with other treatment such as bisphosphonates or Protelos (strontium ranelate). Vitamin D and calcium by itself is not likely to stop the progress of osteoporosis, and certainly won’t reverse the situation.

There is also evidence that frail, elderly women, who may be living in residential accommodation and are likely to be getting little exercise, need to take calcium and vitamin D supplements. Patients who are taking steroids, even if only for their asthma or chronic obstructive pulmonary disease (COPD, such as chronic bronchitis and emphysema), also need to take calcium and vitamin D supplements, and, if there is evidence of osteoporosis, bisphosphonates or Protelos too.

The Lancet trial endorses the advice of the National Institute for Clinical Excellence (Nice) on the prevention of fractures in post-menopausal women. Nice recommends the use of calcium and vitamin D as an aid to bisphosphonate treatment for the secondary prevention of osteoporotic fractures. It contradicts headlines which suggested that “Vitamin supplements fail to maintain bones in the elderly”, “Extra vitamin D in calcium is waste of time”, or “ Vitamin D does not stop elderly fractures”. Women shouldn’t stop taking these supplements without their doctor’s advice.

The BMJ study, was a general practice, nurse-led survey based on a questionnaire. It was sent to elderly women who had at least one risk factor for osteoporosis in the trial. It showed that there was a lower rate of fracture than would have been expected in those who had the vitamin and calcium supplements, but this difference wasn’t great enough to be statistically significant.

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