**9. Types of antioxidant**

 Three types of anti-oxidant found in nature i.e. phytochemicals, vitamins and enzymes. Potent anti-oxidants are found in plants because plants are exposed to ultra violet light throughout of the day. Plants generate high quantity of free radicals but they do not cause cellular damage, because they are protected by naturally occurring anti-oxidant defense system.

#### **9.1 Anti-oxidant enzymes**

These enzymes are basically antioxidant and are synthesized in human body when eat proteins and minerals as our daily diet. The examples of these enzymes are superoxide dismutase, glutathione peroxide, glutathione reductase and catalases. They require co-factors such as iron, copper, selenium, magnesium and zinc for anti-oxidant activity.

#### **9.2 Anti-oxidant vitamins**

 Human body is not able to synthesize or produce these anti-oxidant vitamins naturally but they require for maintaining normal physiology and health, so we take these vitamin in our daily diet. Retinol, l-ascorbic acid, α-tocopherol, folic acid and beta-carotene are the examples of anti-oxidant vitamins.

Retinol is important in tissue repair, for eye health, for improving immune system as well as for improving cholesterol level. l-Ascorbic acid protects our skin from ultra violet light damage and it stimulates immune system by providing resistance from infection and helps in regulating cholesterol level.

α-Tocopherol play an important role in maintaining health of blood vessels and it also improve the skin condition by protect the cell's membrane. Folic acid is useful in the process of erythropoiesis.

Various phytochemicals such as carotenoid provide protection against singlet oxygen and free radicals. These carotenoids are found in orange-colored vegetables like carrot as well as in dark green vegetables like kale, etc.
