The sex hormone oestrogen protects women from heart attacks and may explain why they are far less likely to be struck down than men, claim scientists.
They have discovered that this naturally-occurring chemical helps stop blood cells sticking to the walls of arteries and forming potentially fatal blockages.
Researchers from Queen Mary at the University of London think their findings may explain why women are far more likely to suffer heart attacks after the menopause, when their oestrogen levels decline.
Around one in five men in Britain die from a heart attack, compared to just one in seven women.
But while very few women suffer heart attacks before their 50s, the risk suddenly increases after the menopause when they are just as likely to be struck down than men.
Until recently experts have struggled to explain why younger women are less likely to develop heart disease and suffer heart attacks.
Now research published in the journal Arteriosclerosis, Thrombosis and Vascular Biology claims that the hormone oestrogen may protect them.
But experts say their findings do not necessarily mean that oestrogen could ever be used in drugs to prevent heart disease.
The hormone is known to increase the risk of certain types of cancer.
Dr Suchita Nadkarni from the William Harvey Research Institute, Queen Mary, University of London, who led the research, said: ‘We’ve shown a clear relationship between oestrogen levels and the behaviour of these white blood cells.
‘Our results suggest that oestrogen helps maintain the delicate balance between fighting infections, and protecting arteries from damage that can lead to cardiovascular disease.
‘Understanding how the body fights heart disease naturally is vital for developing new treatments.’
Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation said: ‘We know that women’s health is partly protected by oestrogen. After menopause – when oestrogen levels drop dramatically – coronary heart disease rates rise steeply. It’s not yet clear quite how this protection occurs.
‘This study suggests that oestrogen has another role. The hormone seems to affect women’s response to infection and injury, by preventing white blood cells from moving out of the blood stream into tissues. This reduces inflammation, part of the immune system’s rapid response.’