Blueberries:
Blueberries are a delicious package of antioxidants that help the immune system in scavenging the free radicals in the body and improving the immune system significantly. Blueberries contain a class of antioxidants, i.e., flavonoids, which make the adults 33 percent less prone to get infectious diseases as compared to those who do not take any flavonoids in their diets. Having a handful of this colorful fruit daily helps significantly in boosting the immune system, and there are fewer chances of oxidative reactions happening in your body.