How they help: These mollusks contain more of the mineral zinc than any other food, and zinc has been proven to support and enhance the immune system. Eating just a single oyster will give you a whopping 13 milligrams of zinc. That said, since it may be difficult to work them into your diet regularly (oyster sandwich for lunch?), look to zinc-fortified breakfast cereals, baked beans, and pumpkin seeds to help you get the recommended eight milligrams a day.
Good to know: Zinc is also effective when taken at the first signs of a cold. Oral lozenges that contain the mineral, like those made by Cold-Eeze and Zicam, have been shown to decrease the duration of colds.