WEDNESDAY, Jan. 11, 2017 (HealthDay News) -- A molecule produced in the digestion of red meat, eggs and dairy products is linked to an increased risk of a fatal heart attack or stroke, researchers say.

Patients with high blood levels of trimethylamine N-oxide (TMAO) were six times more likely within the next month to die, suffer a heart attack or stroke, or require surgery to reopen a blocked artery, according to the study.

TMAO also predicted long-term health risks, researchers said. People with the highest blood levels of TMAO were nearly twice as likely to die within seven years.

"A high TMAO level predicted who went on to experience a major cardiovascular event," said lead researcher Dr. Stanley Hazen, chair of cellular and molecular medicine at the Cleveland Clinic's Lerner Research Institute.

TMAO is produced by gut bacteria during digestion of animal-based food, and accumulates in blood plasma, Hazen explained.

Previous animal testing has shown TMAO could increase heart health risks in a couple of ways, he said.

It appears to cause "hair-trigger" clotting by blood cells called platelets, which can lead to a blocked artery, Hazen said.

"If you infuse TMAO into the blood, you can show that platelets become hyper-responsive," he said. "A lower degree of stimulus can produce a more pronounced and more robust degree of platelet activation and more clot formation."

TMAO also appears to contribute to hardening of the arteries by enhancing the ability of cholesterol to form deposits in blood vessels, Hazen added.

To see whether the molecule could be used as a sign of future heart problems, Hazen and his fellow researchers examined two sets of patients -- 530 people in Cleveland and more than 1,600 in Switzerland.

The American patients had been admitted to the ER of the Cleveland Clinic with chest pain, while the Swiss patients had required imaging tests after admission to one of four university hospitals with chest pain.

The patients were followed up for several years to monitor for outcomes such as heart attack, stroke, death from any cause, death specifically due to heart problems, or surgery to reopen a blocked blood vessel.