The protocol lists "saccharine and other sweeteners" as being allowed. I don't think aspartame existed in Dr. Simeons' day so it falls under the category of other sweeteners. It also meets these requirements: "In many countries specially prepared unsweetened and low Calorie foods are freely available, and some of these can be tentatively used." And unless you're growing your own stevia, most of the stuff you buy is processed artificial stuff. If it is white, it isn't real stevia.