While peanut butter is a good source of protein, several whole nuts are just as good sources. banusevim / Getty Images Peanuts, almonds, pistachios, and cashews are among the highest-protein nuts and provide amounts similar to peanut butter. These nuts also provide fiber, healthy fats, vitamins, minerals, and antioxidants. Add nuts or nut butters to snacks and meals for a protein boost. Peanut butter is often considered one of the best plant-based protein foods.