Nature's Bounty® Immune 24 Hour + with Ester-C ®Vitamin C provides advanced, long-lasting immune support to help keep you healthy.* With 1,000 mg of Ester-C®, the clinically studied immune supporting ingredient, is the only Vitamin C that stays in your white blood cells for up to 24 hours, providing immune support around the clock.* Highly bioavailable Ester-C® can increase Vitamin C levels in the body, which is important for white blood cell function, as white blood cells play a vital role in the immune system and contribute to the health of the upper respiratory tract.* For additional wellness benefits, Nature's Bounty® Immune 24 Hour + rapid release softgels contain Vitamin D, Vitamin A, plus Zinc for extra immune and antioxidant support.* In addition, the immune-supporting formula is Non-GMO, and free of artificial flavors, artificial sweeteners, sugar, starch, milk, lactose, soy, gluten, wheat, yeast, fish, and sodium. The Vitamin C 1000mg supplement also includes herbal ingredients Elderberry and Echinacea, plus 9 essential nutrients for your overall health.*