To prevent digestive problems, limit peanuts to the recommended serving size of 1 ounce or about 35 peanuts a day. Sometimes, peanuts can be contaminated by harmful germs that could make you sick.

The serving size for peanut butter is just 2 tablespoons, says Largeman-Roth, which is enough to spread on a sandwich or eat with an apple or banana, for example. The majority of peanut butter ...