Raw onion is a good source of Quercetin. Quercetin is a bioflavoniod and antioxidant compound. It has anti-inflammatory actions. The compound Quercetin is also helps to reduce the allergies. Quercetin is found naturally in the onion especially in the red outer layers of onion. Quercetin is a compound which counter the allergic chemical histamine. Quercetin has anti-inflammation properties therefore, it helps to reduce the severity of asthma.