People who have gallstones are more likely to die within 20 years of diagnosis than people without the disease, a new study says.

Gallstones sufferers are also more likely to die from heart disease or cancer, said the study published in the journal Gastroenterology.

The findings don't mean that one condition causes the other. Instead, gallstone disease and heart disease may have the same root cause, Dr. Philip Barie, professor of surgery and public health at Weill Cornell Medical College in New York, told Reuters Health.

"People with gallstones may have an abnormal balance of fats in their body, including cholesterol, although there's no clear relationship between gallstone disease per se and high cholesterol," said Barie, who was not involved in the study.

More than 25 million people in the U.S. have gallstone disease, and almost one million new cases are diagnosed every year, according to the American Gastroenterological Association.

Gallstones happen when material in the bile hardens and sticks in the ducts leading from the gall bladder, where bile is stored, to the small intestine. Because bile can still get from the liver, where it is made, to where it needs to go, the gallbladder isn't necessary and can be removed.

The researchers looked at the medical records of more than 14,000 people between 20 and 74 years old. About one in 14 had gallstones, and one in 20 had their gallbladders removed between 1988 and 1994.

About one in three people who had gallstones or their gallbladders removed died from any cause during the follow-up time, compared to about one in seven similarly aged people without the disease.

Heart disease claimed the lives of slightly less than one in five gallstone sufferers, compared to one in 20 people without. Death from cancer was also more likely, with one in ten people with gallstones falling victim, compared to one in 25 people without the disease.

The researchers followed all patients until 2006, and recorded all causes of death from the patients' death certificates.

One of the authors on the paper, from Social and Scientific Systems Inc., did not respond by deadline, and the other, at the National Institutes of Health, declined to comment.

Severe gallstones are usually treated by cutting out the gallbladder, said Barie, who does such operations. The risk of dying from an emergency gallbladder surgery is about one in 50, depending on the age of the patient. But if the gallbladder is removed before it becomes an emergency, the risk of dying is only about one in 500, he said.

Barie suggests that people with gallstones keep on a low fat diet to reduce the risks of heart disease or stroke.

"Just a good healthy diet," he said.