Grade A pure maple syrup is a suitable option for the Master Cleanse, as is any pure maple syrup. However, subsisting on the Master Cleanse beverage -- which, along with the syrup, contains just water, lemon juice and cayenne pepper -- is not a healthy way to lose weight as it deprives you of important nutrients.
Maple vs. Table Syrup
The Master Cleanse drink requires pure maple syrup rather than the table syrup you'll find at most diners, which costs less but contains high-fructose corn syrup rather than maple. The grade refers to the color of maple syrup. In the United States, grade A maple syrup is the light variety you drizzle on pancakes, while grade B maple syrup is darker, and typically only used for cooking.
Just because you can use grade A pure maple syrup doesn't mean you should, or that you should use the Master Cleanse system at all. Harvard Medical School reports that this plan lacks needed protein and fats, and that if you take the additional laxative recommended by the program, you risk dehydration. Plus, the starvation slows your metabolism, causing you to regain the weight rapidly once you stop.