Quercetin is a flavonoid – a compound that naturally occurs in many fruits and vegetables. It is of particular interest due to the positive effects it has on human health. It can act as a natural anti-inflammatory, it has anti cancerous properties and has many more benefits. To give you some context, one large red apple contains around 10mg of Quercetin. Quercetin is believed to significantly reduce the risk of heart diseased, simply by eating onions (BBC, 2007). This really does reinforce the importance of having five pieces of fruit and vegetables a day. Let’s take a look at the top five benefits of quercetin.