Research has shown that a healthy diet and physical exercise need to begin early in life to prevent build up of potentially fatal coronary calcium deposits.
"Women cannot afford to wait until middle age to begin a healthy lifestyle. They need to control poor diet, lack of exercise, obesity and high blood pressure while they are still young," Dr Lewis Kuller told a meeting of the American Heart Association.
Dr Kuller from the University of Pittsburg's Graduate School of Public Health is heading the Women's Healthy Lifestyle Project.
"By middle age, the damage from an unhealthy lifestyle could already be done," he said.
The study looked at 535 pre-menopausal women over a period of four-and-a-half years, half of whom were put on a low-fat, low-calorie diet and on a physical activity programme, the other half in a control group.
Cholesterol link
The researchers found that levels of LDL cholesterol - the so-called "bad" cholesterol - before the menopause were linked to coronary artery calcium deposits after the menopause.
The women's arteries were studied using a scanning technique known as electron beam computed tomography.
Women who were estimated as being at high risk at the start of the study, because of factors such as high blood pressure or obesity, had significantly higher levels of coronary calcium.
Those who had coronary calcium had an average total cholesterol of 203mg compared with a level of 189mg in women without coronary calcium.
The researchers also found that women who were heavier and who had larger waists were more likely to develop coronary calcium deposits.
"However coronary heart disease takes many years to develop so it is important that both men and women take steps to prevent it well before middle age," she said.
"Stopping smoking, taking regular physical activity - at least 30 minutes five times a week, and enjoying a high fruit and vegetable, low fat diet are some of the easiest and most effective steps everyone can take to reduce their risk of coronary heart disease."