Antioxidant protection, immune health and more : Getting enough vitamin C is vitally important for overall health but the human body can't make it, so you have to get vitamin C through diet or supplements.1 In fact, some studies have shown that vitamin C supplementation supports certain aspects of cardiovascular health. Plus, vitamin C's biological activity is complemented by the health benefits of the flavonoid quercetin. In fact, vitamin C and bioflavonoids are often present together in healthy foods such as fruits and vegetables, notably citrus fruits. Ultra-absorbable quercetin for immune health and more : There's a long tradition of using quercetin to relieve the effects of seasonal immune challenges. In a randomized clinical trial, quercetin supplementation encouraged a healthy immune response in physically fit older adults. Another randomized controlled trial found similar results in trained athletes.5 And in double-blind clinical trials, quercetin promoted a healthy inflammatory response, reduced oxidative stress and helped maintain overall health.