Stay healthy this winter with Natural Factors® Vitamin C and the preferred D3 form of vitamin D – SunVitamin D3. The newest research suggests that low levels of the “sunshine vitamin” may be part of the reason we get more colds and flu in winter. Increasing year-round vitamin D intake could be another natural way to ward off viral and bacterial infections. Vitamin C is best known for its antioxidant activity and immune function support. Natural Factors Vitamin C 500 mg combines the benefits of vitamin C with antioxidants, such as citrus bioflavonoids, rutin, rosehips, and hesperidin, for added botanical support.