Vitamin E

Figure 1. The chemical structure of alpha-tocopherol form of Vitamin E.

Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. All eight of these vitamers feature a chromane double ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals, and a hydrophobic side chain which allows for penetration into biological membranes. The vitamers occur in alpha, beta, gamma, and delta forms, which are determined by the number and position of methyl groups on the chromanol ring. Vitamin E is synthesised in plants and can be obtained from one's diet.

Vitamin E may have various roles in the human body. It plays a role as a fat soluble antioxidant. In this role, vitamin E acts as a radical scavenger, delivering a hydrogen (H) atom to free radicals. As Vitamin E is fat soluble, it is incorporated into cell membranes, therefore protecting cells from oxidative damage. Vitamin E also affects gene expression and is an enzyme activity regulator, such as deactivating the protein kinase C (PKC) to inhibit smooth muscle growth. Vitamin E also enhances the immune function and prevents clots from forming in heart arteries.

Food Sources

Vitamin E is found in plant-based oils, nuts, seeds, fruits, and vegetables. Sources include:

• Wheat germ oil
• Sunflower, safflower, and soybean oil
• Sunflower seeds
• Almonds
• Peanuts, peanut butter
• Beet greens, collard greens, spinach
• Pumpkin
• Red bell pepper
• Asparagus
• Mango
• Avocado

Taken as a Dietary Supplement

As a dietary supplement, Vitamin E is used to treat Vitamin E deficiency conditions. Vitamin E deficiency often occurs only in people who have digestive disorders or are unable to absorb fat properly, such as due to pancreatitis, cystic fibrosis, or celiac disease. Prolonged Vitamin E deficiency may result in retinopathy (i.e. damage to the retina of the eyes that can impair vision), peripheral neuropathy (damage to the peripheral nerves, usually in the hands or feet, causing weakness or pain), ataxia (loss of control of body movements), and decreased immune function. Vitamin E is also commonly promoted to help reduce the risk of heart diseases, cancer, age-related eye diseases, and cognitive or neurodegenerative diseases.

The Recommended Dietary Allowance for Vitamin E for males and females aged 14 years and older is 15mg daily, including females who are pregnant. Lactating women need slightly more at 19mg daily. The Tolerable Upper Limit for Vitamin E for adults 19 years and older is 1000mg daily.

While Vitamin E is generally well tolerated in the human body, excessive intake of Vitamin E may result in increased risk of excess bleeding, especially when taken together with blood thinning medication.