Besides raising the risk of Oral cancer, smokeless tobacco - also known as snuff, dip or chewing tobacco - appears to boost the odds male users will die from Heart disease, according to the largest study of its kind ever conducted.

The findings contradict earlier research, finding instead that people who chew or “dip” tobacco are 20 percent more likely to be killed by a Heart attack or Stroke than nonusers.

It isn’t clear why smokeless tobacco might contribute to cardiovascular problems, and the study isn’t the final word on the issue, said co-author Jane Henley, an epidemiologist with the American Cancer Society. Even so, the research, released this month in the journal Cancer Causes and Control, should give users another reason to kick their habit, she said.

Some chew users are ex-smokers who turn to smokeless tobacco to “tide them over” as they try to kick the smoking habit. But “any form of tobacco is harmful to your health,” Henley said. “We should be encouraging smokers who want to quit to use nicotine-replacement and other safe therapies.”

In their study, Henley and her colleagues examined two U.S. surveys of American adults, one spanning the years 1959-1972 and another from 1982-2000. Together, nearly 1 million men filled out questionnaires, including almost 10,000 smokeless tobacco users.

The studies encompassed both chewing tobacco, found in pouches and kept between the cheek and gums, and “dip,” also known as “snuff,” which comes in small tins and is “pinched” between the lower lip and gums.

Those who reported using smokeless tobacco when first surveyed were 20 percent more likely to die of cardiovascular diseases compared to those who never used any form of tobacco. They were also 20 percent more likely to die from all diseases combined.

The researchers adjusted the statistics in the study in an attempt to remove the influence of other factors such as age, race, occupation and diet.

Previous studies have both supported and debunked the link between smokeless tobacco and Heart disease, said Henley, who believes more research needs to be done to confirm the findings.

Why would smokeless tobacco pose a risk to the heart? According to Henley, oral use of tobacco may increase heart rate and contribute to clots, which can block blood flow in the body.

Since nicotine replacement therapy seems to be safe, “tobacco itself is probably more harmful than just pure nicotine,” she said.

An estimated 7.7 Americans, almost all male, use smokeless tobacco, Henley said. Part of its appeal is the rush delivered to users.

Also, “it’s really easy to get hold of, and it’s often sold in convenience stores right by the candy,” said Elizabeth Rogers, spokeswoman for Oral Health America.

Smokeless tobacco now comes in several flavors, like wintergreen and cherry, that attract children, she said. Another key to its appeal is the ease of hiding the habit from adults.

Cigarettes, of course, leave telltale signs of smoke, while smokeless tobacco can disappear in an instant. “If the kid is swallowing instead of spitting, they could get away with it a lot easier,” Rogers said.