Most people think of osteoporosis as a disease that affects only older women — indeed, one woman in three in the UK over the age of 50 has osteoporosis — because of a drop in oestrogen levels during the menopause. However, one man in 12 is also affected and now a study published in The Journal of Bone and Mineral Research suggests that the condition may be linked to a B12 deficiency.

The research, which forms part of the ongoing Framingham Study in Massachusetts, measured blood levels of vitamin B12 and bone density in men and women between the ages of 30 and 87. Men who had lower levels of B12 were found to have significantly lower bone mineral density.

Vitamin B12 has long been associated with bone formation. As Professor Peter Selby, consultant physician at Manchester Royal Infirmary, explains: “Patients with pernicious anaemia — a condition which occurs as a direct result of vitamin B12 deficiency — have been shown to have greater risk of fractures for example.”

The vitamin is also linked with levels of homocysteine, an amino acid in the blood which is associated with coronary heart disease and bone fracture risk, says Dr Susan New, a reader in nutrition at the University of Surrey.

The vitamin is found primarily in meat, eggs and dairy products, as well as in leafy green vegetables. Most people get enough vitamin B12 from their daily diet unless they are strict vegetarians, says Professor Selby. “You only need 2.4 micrograms per day and it is stored well by the liver.”

He believes that B12 deficiency is more likely to be caused by an inability to absorb the vitamin, due to lack of a compound known as intrinsic factor, than to poor diet. “Intrinsic factor is secreted by cells lining the stomach and is vital for the proper absorption of vitamin B12 from the small intestine. Older people, those with coeliac disease or low stomach acid, may have problems absorbing the vitamin.”

So should we be taking supplements to prevent osteoporosis? Dr New suggests not. “This new research is important but until we have specific studies which look at the collection of data on vitamin B12 and fractures such as proper supplementation trials we are not in a position to say that the recommended nutrient Intake for vitamin B12 should be higher.”

The best advice, she says, is to eat a healthy balanced diet with a little protein, plenty of fruit and vegetables and enough carbohydrates such as potatoes, pasta and rice.

Osteoporosis is often called the “silent” disease because its discovery can take time. Dr New explains: “It is under-recognised — most people only discover it when they have a bone density scan or, worse still, they actually sustain a fracture.”

Women are at greater risk because during the menopause they experience a sharp decline in their levels of oestrogen, which has a protective effect on bones. The process of bone renewal is thought to be controlled by the sex hormones — it is now believed that men, too, produce low levels of oestrogen throughout their lives which may be equally important for their bones. Furthermore, a low level of the male hormone, testosterone “is also a risk factor for osteoporosis” , says Trevor Reed, of the National Osteoporosis Society.

But it appears that most men develop the disease through long term use of steroidal drugs such as those used to treat asthma and arthritis (these interfere with the bone-building cells) or from other medical conditions such as Cushing’s syndrome or liver and thyroid problems. Heavy drinking, which inhibits the absorption of calcium, and smoking, which appears to affect the bone cells, may also put them at risk.

However, for around a third of men with osteoporosis there is simply no known cause — this is known as male idiopathic osteoporosis.

Ian Foster believes that in his case it is probably genetic. “Because of my job I knew that men did get the disease but I was really shocked, particularly as I have always lived a healthy lifestyle — eaten plenty of fruit and vegetables, drunk milk as a child and done lots of weight training and bone loading exercise such as running.

“But my parents. who are in their eighties, recently discovered they have osteoporosis and my sister has also had it diagnosed. I do remember as a child I used to break bones easily so I suppose I could have had it for years.” he explains. He now takes bisphosphonates, which prevent bone being reabsorbed by the body (this is the only medication licensed for treating osteoporosis in men).

• National Osteoporosis Society, 01761 471771 www.nos.org.uk

  Nutritional Aspects of Bone Health by Dr Susan New is available from the Royal Society of Chemistry www.rsc.org