The Food and Drug Administration (FDA) has specific definitions for conventional foods and dietary supplements, but protein powders can fall into one or the other. There are no definitive guidelines for protein powders, and a product’s category (and, thus, label) depends on how the manufacturer intends the product to be used. If it’s intended to replace one or more items of a meal or diet (as with a conventional food), then it displays a Nutrition Facts panel. Otherwise, it should be labeled as a dietary supplement and display a Supplement Facts panel. You should also be aware that if a protein powder is labeled as a dietary supplement and makes a “structure/function claim,” the law requires that the label carry a disclaimer that FDA has not evaluated the claim and the dietary supplement product is not intended to “diagnosis, treat, cure, or prevent any disease.” On the other hand, structure/function claims made for conventional foods do not require a similar disclaimer. Please see this OPSS FAQ on labeling of dietary supplement products for more information. https://www.opss.org/faqs/protein-powders-why-do-some-protein-powders-have-nutrition-facts-labels-while-others-have