Advanced Nutrition by Zahler Vitamin C and Bioflavonoids Advanced Vitamin C Formula General Health Dietary Supplement Kosher Pareve Manufactured in a GMP Certified Facility Non-GMO Gluten Free Dairy Free Soy Free Vegetarian Friendly Feel Better, Everyday Advanced Vitamin C Vitamin C is an essential antioxidant that helps support the immune system. Since Vitamin C is water soluble and the body cannot store it, a continuous supply is needed.