These Chicken and Apple Chews contain Vitamin E, Vitamin C, and Zinc which helps restore and boosts their immune and digestive system. Immune-Boosting, Antioxidant-Rich Natural Dog Treats: The Immune Max Chews are all natural dog treats made from real chicken and apples; no wheat, corn, or soy! These treats contain Vitamin E, Vitamin C and Zinc which helps restores and boost their immune system and can aid in digestion. They also have added Calcium to help support strong teeth and bones.