Go ahead and have that second cup of coffee. A study recently published shows heavy, long-term coffee drinking does not raise the risk of heart disease for most people.

The study, which followed 128,000 men and women for as long as 20 years, showed that drinking filtered coffee -- not espresso or French-style brews -- did not raise the risk of heart disease.

Heavy coffee drinkers did tend to smoke and drink alcohol more often and those two factors clearly do raise heart risk, the researchers report in the journal Circulation.

"We believe this study clearly shows there is no association between filtered coffee consumption and coronary heart disease," said Esther Lopez-Garcia, an instructor in the School of Medicine at the Universidad Autonoma de Madrid in Spain, who worked on the study.

"This lack of effect is good news, because coffee is one of the most widely consumed beverages in the world."

Researchers also found no link between heart disease and how much caffeine, tea or decaffeinated coffee people drank.

But this does not mean that everyone can overload on coffee with impunity, said Rob van Dam of the Harvard School of Public Health in Boston.

"We can't exclude the association between coffee consumption and the risk of (heart disease) in small groups of people," Van Dam said in a statement.

In March, a study published in the Journal of the American Medical Association showed that people with a "slow" version of a particular liver enzyme gene had a higher risk of heart disease if they drank more coffee, compared to those with a fast-metabolizing version. Liver enzymes metabolize coffee and many other compounds.

And several studies have shown a link with heart disease and copious drinking of French press coffee, made using a mesh filter instead of a paper drip filter, or perked coffee.

The Harvard and Madrid teams used data from two ongoing studies -- the all-male Health Professionals Follow-up Study, which began in 1986, and the all-female Nurses' Health Study, which started in 1976.

Volunteers in both studies fill out periodic questionnaires about their diet, exercise and other health habits and undergo regular physical exams.

The researchers found more than half the women and 30 percent of men who drank six or more cups of coffee a day were also more likely to smoke cigarettes, drink alcohol and use aspirin, and were less likely to drink tea, exercise or take vitamin supplements.

But once these factors were accounted for, there was no difference in heart attack risks between the very light and heavy coffee drinkers.

A study published last November found no link between coffee drinking and high blood pressure, but an apparent association with drinking caffeinated sodas.