Vitamin C, an essential antioxidant, is often sold with plant-based substances called flavonoids in a single product. While each supplement can be purchased individually, there are several reasons to consider a product that combines the two.

For one, flavonoids–the catchall term for some 4,000 antioxidant compounds responsible for the color and numerous health benefits of fruits, vegetables, and herbs–enhance the body’s absorption of vitamin C. Key flavonoids include quercetin, rutin, genistein, grape seed extract, and naringen.