With 69% plum and 22% agave syrup, their jam is delicious and very healthy. Agave syrup has a lower glycemic index than regular sugar, so it doesn't cause such a drastic increase in glucose levels. Plum is rich in water, fiber, and carbohydrates, but it contains very little fat or protein. It is the quintessential laxative fruit that also provides vitamins A, C, and E.