Sex is good for the heart because it reduces the levels of a harmful chemical in the blood, scientists believe - but the effect is only seen in men.

Having sex several times a week can cut lead to better circulation and healthier blood vessels in men, which researchers say is crucial for preventing a build-up of the chemical homocysteine.

But scientists say women benefit much less because sexual arousal is less dependent on having a healthy blood flow, which is a key factor in keeping homocysteine under control.

Heart disease is the biggest killer in Britain.