I found the following on the company's webpage (http://www.nowfoods.com/Foods/Real-Food/Products/M004070.htm) for this product:
Ingredient: Agar-Agar Powder (100% Pure).
Contains no: sugar, salt, starch, yeast, wheat, gluten, corn, soy, milk, egg or preservatives.
Let me start by saying, I have never made marshmallows, in fact, don't like them. From the book "Food Lover's Companion": Agar; agar-agar also called kanten and Japanese gelatin, is a tasteless dried seaweed. It acts as a setting agent and is widely used in Asia. It is marketed in the form of blocks, brittle strands and powder. Agar can be substituted for gelatin but it has stronger setting powers (about 5x's greater) so less of it is required. Unlike gelatin, it will set at room temperature. It may take some experimenting to get the texture you want. Please let me know how you do. G.ma Jane