Nutritional Information High in fibre, Grapefruit has significant amounts of nutrients, namely Vitamin C, Vitamin B1 Thiamine, Vitamin B9 - Folate as well as potassium and pectin. The active constituents of Grapefruit are naringin, which are flavonoids as well as furanocoumarins like bergamottin. Drug Interactions Increased bioavailability and plasma concentrations of numerous drugs potentially lead [...]