Gelatin helps to make foods more gelatinous. Gelatin dessert, for example, is usually made from gelatin sheets or powder combined with liquid. Doughnuts don't need the wobbly, firm texture of gelatin dessert, so a simple doughnut recipe includes flour, sugar, butter, water, a little egg -- and no gelatin.

It's difficult to know exactly what ingredients are in a store or restaurant doughnut. A plain doughnut is unlikely to contain gelatin, and large doughnut stores may avoid gelatin in all of their products. For example, one major doughnut company does not list gelatin in its ingredients and states that no animal products other than eggs and dairy feature in their doughnuts -- which rules out gelatin.

Doughnuts that contain homemade or quality fruit jelly or jam usually don't have gelatin. The thickening agent in jelly is usually fruit pectin. However, jellies or fillings at times contain gelatin, so it's worth checking the ingredient label or making your own filling. Glaze can include gelatin, though more commonly consists of powdered sugar and butter.

While the doughnut and its filling may be gelatin-free, other possible sources of gelatin might come along with your snack. For example, gummy candies, fruit sweets and marshmallows often contain gelatin to provide a chewy texture, so a doughnut with extra toppings or candy side treats could mean you end up eating gelatin accidentally.