When you go hunting down the best peanut butter, only opt fororganic varieties. Non-organic peanut butters tend to be drowning in pesticides and fungus and contain aflatoxin, known for being a potent carcinogenic mold. Peanuts are just as packed with protein as soy. You can mix in Brewer’s yeast to boost the protein content of your favorite peanut butter. Vegetarians, you’re welcome.