Maple syrup (grade B) supplies many important minerals and vitamins during the Master Cleanse. It contains sodium, potassium, calcium, magnesium, manganese, iron, copper, phosphorus, sulphur, chlorine and silicon. Vitamin A, B1, B2, B6, and C, nicotinic and pantothenic acid. Grade B is best as it is a darker syrup and is richer in minerals being less refined. It is sometimes sold as "cooking" maple syrup and is often cheaper than the clearer "A" grade.
I believe it has a superior flavor and fragrance, and thats good enough for me.
Also, my 2nd best reason....Burroughs recommended it in his Master Cleanse protocol.