Yes, tuna salad sandwiches are usually high in protein. Tuna is an excellent protein source, containing around 20 grams of protein per 100 grams. Additionally, the mayonnaise used to make the tuna salad usually contains protein and any other ingredients, such as eggs or cheese, that may be added. Bread also has a small amount of protein, but the protein content of a tuna salad sandwich will largely depend on the type and quantity of ingredients used in the salad.