BioEd Online

A dose of fat in the diet helps to create a safe haven for the trillions of useful bacteria in the gut - and could help to reduce complication after surgery.

A study in rats shows that fat kicks into action a hormone that keeps inflammation in the gut at bay, protecting intestinal bacteria from harm. The researchers don't suggest that people start chomping on hamburgers to keep their intestines happy. But they do think their finding might have implications for patients.

Patients are routinely asked to fast before major surgery to prevent vomiting during anaesthesia. But Wim Buurman at the University of Maastricht in the Netherlands, who led the research, thinks that fasting could deprive patients of protective fat and increase the risk of complications. "There is a strong trend in the world of surgery at the moment that suggests that we are probably doing wrong by not giving people food," he says.

Shock findings

People normally live in harmony with the bacteria in the gut, many of which produce nutrients and promote health. But sometimes these microbes prompt an inflammatory response in which immune cells bombard the gut. An overactive inflammatory response may underlie many bowel diseases and can run rampant after traumatic accidents or surgery, resulting in shock and potentially fatal sepsis.

Buurman and colleagues had previously found that feeding rats fat protected them against shock. So they set out to ask why, using a blend of vegetable fats normally used to feed patients through intravenous tubes.

They found that fat stimulated the hormone-induced production of acetylcholine, which binds to immune cells and dampens inflammation. To prove the connection, the researchers treated some rats with a molecule that blocks the action of acetylcholine, and found that fat was unable to dampen inflammation.

The findings, reported in The Journal of Experimental Medicine¹, suggest that fat helps to keep the immune system in check. The researchers think that a range of fats, from butter to margarine to olive oil, might have the same effect.

Comfort food

The researchers would also like to test whether fat could treat animal models of inflammatory bowel disease. "Theoretically you could say fat would have a positive impact," says Misha Luyer, an author on the study.

Kevin Tracey, who studies inflammation at The Feinstein Institute for Medical Research in Manhasset New York, cautions that no one knows if the same effect happens in people. But, he adds, several studies have hinted that fat might have a positive effect. Fish oil, for instance, eases the symptoms of ulcerative colitis, one of the most common forms of inflammatory bowel disease.

Buurman and colleagues also plan to test the idea that fats could protect against excess inflammation during surgery. Previous studies have suggested that feeding patients through a tube before surgery helps them recover, but no one knows why and hospitals still routinely ask patients to fast.

"A lot of our patients who have had very heavy surgery end up in the intensive care unit," says Buurman. "Our prime goal is to see how we can reduce that."