Zinc, an essential trace element with antioxidant properties, plays a vital role in maintaining a healthy immune system. Individuals who suffer from mild to severe zinc deficiency are more prone to a variety of illnesses, but even those without a deficiency have been found to benefit from the administration of zinc, either in lozenge or spray form, at the early onset of a cold or flu. In order to maintain proper zinc levels in your diet, be sure to eat foods rich in the element, such as red meat, seafood, nuts and eggs.