What are dietary indoles and how are they derived?

Dietary indoles are compounds formed in response to a catastrophic disruption within plant cells. They are found in a wide variety of plants but are most frequently associated with cruciferous vegetables such as broccoli, cauliflower, cabbage, and Brussels sprouts. When cell walls are broken through chopping, chewing or juicing, an enzyme called myrosinase is liberated and freely reacts with a family of compounds called glucosinolates to form isothiocyanates, thiocyanates, nitriles, and indoles. Dietary indoles are formed from a glucosinolate called Indole-3-glucobrassicin. There are a wide range of indole compounds with different activities and synergies.

While it is possible to extract various dietary indoles from certain vegetables, their concentration is not sufficient to make extraction economically viable. All commercial sources are almost certainly synthetic. Any source of I3C or DIM claiming to be completely natural is more than likely being misrepresented.