Pro Zero Pro Zero is a low protein milk replacement consisting of carbohydrate & fat for use in the dietary management of inborn errors of metabolism from 6 months of age. It can used be in a similar way to milk, e.g. as a drink, on cereal, in tea or coffee & in recipes. Pro Zero is a food for special medical purposes & should only be used under medical supervision. Pro Zero contains milk fats & milk sugar (lactose).