Sundown Naturals Vitamin C is a time release formula that's ideal for antioxidant and immune system support. As one of the leading vitamins for immune health, Vitamin C is important for the functioning of white blood cells, which are vital components of the immune system, and contributes to heart health. This antioxidant vitamin also provides support for healthy gums. These one-per-day capsules are specially formulated to provide a gradual release of Vitamin C over a prolonged period of time.