Smoking is 25 percent more likely to give women heart disease than men, a study has revealed on Thursday. Toxic chemicals in tobacco smoke may have a more potent effect on women due to biological differences, scientists said. US researchers analysed pooled data on around four million individuals from 86 studies. After adjusting for other risk factors, they found the increased risk of heart disease linked to smoking was 25 percent higher for women. The longer a woman smoked, the greater her heart disease risk was compared with that of a man who had smoked for the same length of time. A woman\'s extra risk increased by 2 percent for every additional year she had been smoking. The findings are published today in an early online edition of The Lancet medical journal here. Authors Dr Rachel Huxley, from the University of Minnesota, and Dr Mark Woodward, from Johns Hopkins University, of Maryland, wrote \"women might extract a greater quantity of carcinogens and other toxic agents from the same number of cigarettes than men. \"This occurrence could explain why women who smoke have double the risk of lung cancer compared with their male counterparts. \"Physicians and health professionals should be encouraged to increase their efforts at promotion of smoking cessation in all individuals. \"Present trends in female smoking, and this report, suggest that inclusion of a female perspective in tobacco-control policies is crucial.\" In the UK, 21 percent of women and 22 percent of men smoke cigarettes. Ellen Mason, senior cardiac nurse at the British Heart Foundation, said \"It\'s alarming to see such a large study confirm that women are so much more at risk of heart disease from smoking than men. \"Despite women generally smoking fewer cigarettes a day than men, women appear to be substantially more at risk of getting heart disease. Biologically, women seem more susceptible to the dangers of smoking and passive smoking. A Department of Health spokesperson said \"Over 80,000 people die in England each year from smoking-related diseases - this includes both men and women. \"That\'s why in March we published our plans to help drive down smoking rates and reduce the harms from tobacco over the next five years\".