Those alternatives to traditional milk are usually obtained by macerating the dried fruit/cereal in water and filtering the liquid from the solid part. What remains is an emulsion of fats, water and proteins with a milky resemblance. Being more and more requested as replacement of cow milk, those beverages are often fortified with vitamins as type A, D e B12, to prevent deficiencies. Although the sweetened versions are more yummy, I suggest to use to the plain ones in your recipes.