HRT may not protect the heart

HRT can prevent bones thinning and fracturing with age

Scientists believe they could have discovered why hormone replacement therapy (HRT) might be powerless to prevent heart disease following the menopause.

Rates of heart disease in women rise sharply after the menopause, and this has been attributed to changes in the woman's hormone supplies.

The traditional logic follows that by maintaining these hormones with HRT, the protection can be extended.

However, although some studies apparently show HRT has a protective effect, large-scale research published last year found no signs of benefit.

Researchers perplexed by this now say there could be a separate age-related change in the body's chemistry which results in the higher risk of heart disease.

This is called "methylation", a process which stops the walls of the arteries being able to respond to oestrogen's beneficial effects.

Heart disease often requires complicated surgery

The research, published in the journal Cardiovascular Research, found that genetic receptors for oestrogen become clogged up with other molecules.

When hardened arteries taken from women with known heart disease were compared with unhardened arteries, there were almost three times more clogged, or "methylated" genes.

'A significant step'

Dr Wendy Post, who led the research team, said: "We've been looking for the link between oestrogen, menopause and atherosclerosis (hardening of the arteries).

"Having oestrogen receptor genes shut down so tissues can't respond to oestrogen appears to be a significant step."

Other studies have found that the older the person the more likely they are to have more methylated genes.

However, there are still clear clinical benefits to taking HRT, not least of all, the protection it offers from brittle bone disease, or osteoporosis.

It also reduces the symptoms of the menopause, such as hot flushes or mood changes.

Another study has shown that this protection extends into the mouth, with women who take HRT enjoying better dental health.

Research found that oestrogen supplements may reduce gum inflammation and protect the fibres and bone which support the teeth.

Dr Richard Reinhardt, of the University of Nebraska Medical Center said: "For women at risk for osteoporosis, which likely makes them more vulnerable to rapid periodontal bone loss, this may be yet one more reason to be on oestrogen.

"However, female smokers should note that the study found that smoking had a greater impact on speeding the progression of periodontal disease that oestrogen deficiency."