We don't know how it causes cancer, but it is known to cause cancer in mice, and people with colon cancer have high concentrations of it

Dr David Mangelsdorf

Highly toxic

Unlike most other acids LCA remains in the gut and then goes into the large intestine or colon, instead of circulating to the liver.

Dr David Mangelsdorf, a pharmacology expert, from the University of Texas said the acid had been shown to cause cancer in mice.

"Lithocholic acid is highly toxic and builds up in a high-fat diet.

"We don't know how it causes cancer, but it is known to cause cancer in mice, and people with colon cancer have high concentrations of it."

The scientists said vitamin D, which is already thought to reduce the risk of heart disease, can keep LCA levels under control.

Using mice they found that the vitamin triggered production of an enzyme which broke down the acid.

But the scientists warned that vitamin D should not be overdone because an excessive build-up of the calcium can itself be toxic.