Bacteria present in the gut can give off substances which offer protection against colon cancer and inflammatory bowel disease, scientists found.
Scientists at the University of Aberdeen Rowett Institute of Nutrition and Health and from the MTT Agrifood Research Institute in Finland showed that bacteria in the human gut convert linoleic acid, a naturally-occurring fat in the diet, into a form called conjugated linoleic acid (CLA) which is absorbed by the gut wall.
Dr John Wallace of the Rowett Research Institute said that there exist different types of CLA, out of which only a few have beneficial effects, and that "good" form of CLA is present in dairy foods such as milk and cheese."
"But eating lots of dairy foods won't necessarily help our gut health as most of the fats are digested in the small intestine before they get to the large intestine, where most of our gut bacteria are found," he said.
The findings indicated that gut bacteria produce several different forms of CLA, most of which are of the "good" kind.
Bit Wallace stressed that more extensive studies are needed, as one subject produced small amounts of a CLA whose effects are much less clear.
Thus, the researchers deduced that if small quantities of dietary linoleic acid could be delivered to the large intestine, the effects on gut health would be generally beneficial in most people.
"The results are of special interest for individuals using anti-obesity treatments that prevent the small intestine from absorbing fats. This means that those fats - including linoleic acid - will pass into the large intestine and the gut bacteria will produce CLA. It has to be the correct CLA, so it is important to understand how individuals produce different CLA. This must depend on which types of bacteria are present," said Wallace.
The study has been published in the journal Microbiology.