Truly one of the best superfoods, beef liver provides the highest level of preformed Vitamin A of any other food. In addition, it is an excellent source of the B vitamins (especially B12), as well as minerals like iron, copper, and the fat-soluble vitamin D. Many of these nutrients are notoriously difficult to obtain in our typical diets, so including even a small dose of beef liver regularly in the diet is sure to make a big impact.