LONDON "Good" bacteria commonly found in probiotic yogurts and drinks may be fatal for people with severe cases of pancreatitis, Dutch researchers said on Thursday.
More than twice as many patients with severe forms of the disease given probiotic supplements to prevent infections died compared to those who received placebos, the researchers reported in a study in the Lancet medical journal.
"The adverse effects of probiotics noted here were unexpected," Hein Gooszen and colleagues at the University Medical Centre Utrecht in the Netherlands wrote. "Several studies have associated probiotics with a reduction in infectious pancreatitis."
Gooszen was careful not to link probiotics to any other specific condition but said they should not be given to severely ill patients with organ failure and on a feeding tube.
Probiotics contain live microorganisms, usually so-called good bacteria, that colonize the intestine. They are sold as supplements but also found naturally in many fermented food including yogurt and certain juices.
Humans normally carry several pounds of bacteria in their intestines, and they are key to digestion, immune system function and possibly play other beneficial roles. They can also out-compete "bad" bacteria that may cause disease.
They have been used as a treatment for pancreatitis, an inflammation of the pancreas that can precede pancreatic cancer. The condition usually develops and subsides quickly but can destroy the function of the vital organ when untreated.
Complications are common and about a fifth of people with pancreatitis develop a severe form of the disease that raises the risk of death, mainly due to infections.
In the study of 296 people with similarly acute forms of pancreatitis, one group received a placebo and the other a mixture of probiotic supplements, some commonly available.
The number of people who developed infections was similar but 24 volunteers died in the probiotic group compared to nine in the placebo group, the researchers said.
The team said it did not know exactly why probiotics may be harmful but speculated the supplements may somehow boost demand for oxygen and worsen already reduced blood flow.
Other experts said that while probiotics are safe, they should not be given to patients with severe acute pancreatitis, an ailment largely due to gallstones or heavy alcohol use that has no satisfactory, specific treatment.
"Probiotics are safe and may be beneficial in many people who are not critically ill," Robert Sutton, a researcher at Royal Liverpool University Hospital, who was not involved in the study, said in a statement.
(Reporting by Michael Kahn, Editing by Maggie Fox)