Strong Immunity

Black tea contains many antioxidants, one of them being quercetin (also found in onions), which combats inflammation and improve immunity system.

The Fruit That Helps Fight Lung Disease

Apples are known for their protective effect on the lungs and the bronchial tubes as they have a high content of the Bio-flavonoid nutrient called quercetin.

Quercetin acts like an anti inflammatory and anti allergic medication in the body. It inhibits the pro-inflammatory molecules in the body like histamine and leukotriene that create the vasoconstriction and broncho-constriction that causes asthma attacks.
About Quercetin:

Quercetin is a phytochemical that is part of the coloring found in the skins of apples and red onions. It has been isolated and is sold as a dietary supplement.

In the Body:

Quercetin is a powerful antioxidant. It is also a natural anti-histamine, and anti-inflammatory. Research shows that quercetin may help to prevent cancer, especially prostate cancer.

Why Use It:

Quercetin's antihistamine action may help to relieve allergic symptoms and asthma symptoms. The anti-inflammatory properties may help to reduce pain from disorders such as arthritis. Men who are concerned about prostate problems would also benefit from quercetin. Quercetin may also help reduce symptoms like fatigue, depression and anxiety.

Source: about.com