“An apple a day keeps the doctor away.” We’ve all heard that before. That’s because it’s true. But not just about apples. Eating right is the broader meaning of the saying, and eating well helps to keep your body functioning normally, including your immune system. When you supply your body with the nutrients it needs, you help support a healthy immune system. Being deficient in just one or a few essential nutrients can impair your immune system function, making you more susceptible to disease and illness.