There is so much you can do for yourself to better bone health in your body.

Last week we looked at bone health in general. Today we will explore the myths and how they can be explained. Women feature highly in the worrying condition of osteoporosis and therefore become concerned about bone health as they get older. Most hip fractures suffered by women are sustained from a fall in older years.

When these are examined and compared with a healthy control group, there is considerable similarity between the two in bone mineral density and bone mass. This suggests that other responsible factors could be physical inactivity, loss of muscle strength, impaired vision, chronic illness and the use of one or more prescription drugs (Ageing Res. Rev., 2003).

Interestingly, although one fifth of elderly patients die within a year of a hip fracture, it is not clear whether their death is due to the fracture or to their general frailty (J. Am. Geriatr. Soc., 2006). So, bone health is not always the reason for hip fractures. Lifestyle choices can be a contributory factor.

Measuring bone mass could be a meaningless measure of the true fracture risk. A recent study found that about half of the patients who had sustained fractures had bone mineral density scores of above the diagnostic T score of -2.5, which should have meant that their bones were supposedly not at risk (J. Musculoskelet. Neuronal Interact, 2004).

Such studies suggest that the rate of bone turnover (bone ‘resorption’) and very low levels of hormones, such as estradiol and DHEA, may be a better indicator of true fracture risk than bone mineral density.

One study followed nearly 150,000 postmenopausal women for a year after having a Dual Energy X-ray Absorptiometry (Dexa) scan, which is a test that measures the density of bones.

The denser the tissue, the less X-rays pass through. Air and water are less dense than solid bone. This is because particles which make air and water are not held closely together. The general belief is that the denser the bone, the stronger it is and the less likely it is to break.

However, in the study, those at high risk had only 18 per cent of the osteoporotic fractures observed, indicating that 82 per cent of those with good T scores and good bones had a fracture during the same year (Arch. Intern. Med., 2004).

Women feature highly in the worrying condition of osteoporosis

According to the National Osteoporosis Foundation (NOF) in the US, nearly 22 million American women and close to 12 million men have osteopenia. This is a relatively new term used to describe someone whose bone density is slightly less than that of a healthy person but not as low as someone with full-blown osteoporosis.

A radiologist carrying out the Dexa test will measure a variety of bones in the body and the bone density is then calculated by working out the difference between the two beam readings and comparing them against the ideal.

It is interesting to understand how the final T score is arrived at. Osteoporosis is determined by the T score as a measure of bone density, which is set at zero, representing the score of an average young woman in her 20s at peak bone density.

An older woman past the menopause is overwhelmingly likely to have a negative score. The World Health Organisation arbitrarily set the T score for osteoporosis at -2.5. Having a score between -1 and -2 standard deviations, lower than the ideal young person, would result in a diagnosis of osteopenia.

Recent evidence measuring older people against a young standard as a measure of bone health places some 34 million women and men in the US in the category of having osteopenia. It has been pointed out by American nutritionist and bone health expert Susan Brown that young people are no longer a yardstick of good health. Some 16 per cent also have a bone density score of -1 T or lower and, by that definition, would also have osteopenia.

The goalpost between osteopenia and osteoporosis also keeps moving. In 2003, the NOF redefined a T score of -2, previously the lowest level defined as osteopenia, as now representing full-blown osteoporosis.

The effect of that change in definition was to immediately reclassify 6.7 million American women who had been characterised as being borderline healthy as now having osteoporosis, thereby requiring medical treatment.

The T score does not take into account the Z score, which is the score compared with people of your own age, gender, racial origin and weight, all of which can affect your fracture risk. It is perfectly healthy to lose bone mass as we age. The problem isn’t mass but the ability of bone to self-repair.

Once again, a health condition is based on a score defined by an organisation, which in turn can greatly affect how we live our lives. There is so much you can do for yourself to better bone health in your body.

kathryn@maltanet.net