Caffeic acid metabolism by bacteria of the human gastrointestinal tract

The metabolism of caffeic acid, previously shown to be carried out by the intestinal microbiota of man and experimental animals, has now been examined in a number of bacteria isolated from human feces. It has been found that of the 12 organisms isolated none has the ability to catalyze more than one reaction of the series leading from caffeic acid to either m-hydroxyphenylpropionic acid or 4-ethylcatechol.