If you are vegan, lactose intolerant or allergic to dairy, you can still enjoy the benefits of high protein milk by choosing plant-based options. Generally soy milk has the highest amount of protein. These milks also have other nutrients and health benefits, such as omega-3 fatty acids, fiber, iron and calcium. However, some nutrients such as vitamin B12 and zinc may not be absorbed as well. Therefore, it is advisable to choose fortified plant-based milks and supplement your diet with other sources of these nutrients.