"我那同事说她吃ORGANIC FOOD长大的孩子一吃外面的东西就闹肚子." -- nonsense. It is not because of organic food, it is because they clean the food too well at home, and go out to a not clean restaraunt.
In fact, it is more likely to 闹肚子 when eating ORGANIC vegetables -- no pesticide used when growing, more likely to have germs. Heard about recent E.Coli case?