**4. Tea phytochemicals as Nutraceuticals in different diseases**

Tea is beneficial in protection and prevention of numerous critical diseases such as different cancers, diabetes, neurodegenerative and cardiovascular diseases [29–31]. The polyphenols, the major phytochemicals present in tea are known for their antioxidant properties due to their abilities to scavenge free radical species such as hydroxyl radical (OH), hydrogen peroxide (H2O2) and superoxide anion (O2.) and thus their consumption confer them as potential cancer chemopreventive agents as well as other free radical induced diseases. The polyphenol extract of tea has been effectively used in cancer prevention, protection cardiovascular diseases, reduce weight-loss, anti-allergic, prebiotics, osteoarthritis protection etc. [32, 33]. Green tea extract comprises of nearly 40% of polyphenols of which nearly 25% accounts for different catechins and their gallates of which EGCG is the highest in quantity (about 11%), the most studied polyphenols in therapeutic properties. Black tea polyphenols theaflavins, theaflavin gallates (which are dimers of two different catechins and their gallates) and thearubigins with 2-6% in quantity in addition to 3-10% of catechins gain attention in different diseases [34].

Herein, we wish to discuss the health benefits of tea in common and major diseases such as diabetes, cardiovascular diseases, obesity, cancers, as well as others minor diseases related to microbial and inflammatory types. The role of major phtochemicals of tea in different diseases is outlined in **Table 3**.
