Since food allergies are closely related to the immune response and the immune system, ensuring that your immune system is working correctly is crucial to avoiding allergic reactions. Vitamin C is the most easily accessible and most effective booster for our immune system, as it stimulates the production of white blood cells and acts as an antioxidant within our body’s systems. Flooding your system with vitamin C is a great way to counter the effects of food allergies. Some of the most vitamin C-rich foods include peppers, papaya, cauliflower, pineapple, kiwi, mango and strawberries.