Vitamin E comprises a combination of 8 different compounds (4 tocopherols and 4 tocotrienols) that exhibit vitamin E activity. The tocopherols include isomer alpha-tocopherol, beta-tocopherol, gamma-tocopherol and omega-tocopherols. They are all derivatives of tocol or 6-hydroxy chromane ring with phytyl side chain. All the tocopherols are alkaline sensitive, and their vitamin activity is destroyed through oxidation. Of all the tocopherols, alpha-tocopherol is the most potent and widely distributed in nature. Vitamin E is only found in plant dietary sources such as oils, nuts, grains, wheat and fruits. Therefore, excessive cooking and food processing may destroy vitamin E to some extent. It is fats-soluble hence, stored in the body and used as needed. Each isomer of vitamin E confers unique properties and hence functions and applications especially in the manufacture of food and beverage products. To begin with, the dietary tocopherols maintain cell integrity by functioning as antioxidants and free radical scavengers. It also prevents the peroxidation of membrane lipids especially polyunsaturated fatty acids (PUFA) of membrane phospholipids.
Vitamin E supports the immune system. First, it has the ability to reduce free radical damage and promote health which confers its immune-supportive function. As an antioxidant, vitamin E protects cells from damage. The alpha-tocopherols present in the membrane protects membrane lipids from radical attacks to cause a change in membrane structure. The damage of body cells increases susceptibility to invasion by foreign bodies. Vitamin E, therefore, acts as a chain-breaking antioxidant. The antioxidant function is also helpful when exposed to risk factors such as ultraviolet light or cigarette smoke. Its antioxidation function also, balances cholesterol preventing its transforming into a toxic form.
Additionally, vitamin E plays a role in the maintenance of muscle tone. Most of the vitamin E is normally stored in the skeletal muscle and adipose tissue. It also has a metabolic role that ensures optimal body functioning.
Vitamin E is beneficial to the skin as it strengthens the capillary walls and therefore, their moisture and elasticity. Additionally, it enhances the healing process of the skin by speeding up cell regeneration. It is absorbed by the epidermal layer of the skin. As such, vitamin E slows down the aging process and aids in the improvement of athletic performance such as running by reducing the oxidative stress on muscles post-exercise. Vitamin E counteracts the formation of free radicals that weaken and break down healthy cells hence promoting longevity.
Other therapeutic uses of vitamin E include the ability to induce apoptosis. This helps in the elimination of damaged cells or DNA thus minimizing errors. Modified Vitamin E is a proapoptotic agent that is used in the process of eliminating such cells.
Vitamin E deficiency is rare. The daily requirement for an adult is up to 10mg per day. However, during states of increased physiological needs such as in pregnancy or during lactation, the amount increases to about 12-13mg/day. It entails a deficiency in the intake of all the isomers. At times Vitamin E toxicity may occur due to self-medication with large doses of vitamin E.