Modulation of equol production via different dietary regimens in an artificial model of the human colon

In order to find dietary conditions favouring endogenous equol biosynthesis, a pooled faecal homogenate from equol-producing women was used to inoculate the TIM-2 artificial model of the human proximal colon. The model was fuelled with control diets not supplemented (C) or supplemented (C-ISO) with isoflavones, and two isoflavone-containing diets rich in carbohydrate (CH-ISO) or protein (PR-ISO). Compared to the C-ISO control, the CH-ISO diet doubled the production of equol, while with the PR-ISO diet the production of equol in cultures decreased sharply. The CH-ISO diet was also associated with enhanced butyrate production. The numbers of most bacterial populations analysed did not significantly change along cultures with any of the diets. Surprisingly, counts for a gene involved in equol production (tdr) were reduced in all cultures, reflecting a reduction in the number of equol-producing bacteria. In conclusion, under the TIM-2 culture conditions established, the CH-ISO diet favoured the synthesis of equol.