Lesson 18: Vitamin E Copy

Vitamin E

Without vitamin E, we essentially turn rancid. Vitamin E is fat-soluble, that is, able to penetrate the fatty areas of our tissues. As it does so, it neutralizes toxic oxidants and protects oxidant-sensitive membranes. Thus vitamin E is justifiably known as an antioxidant, and for helping to prevent age-associated increases in oxidative insults to our bodies. Vitamin E is for the Excellent Eight. A family of eight antioxidants, vitamin E protects essential lipids from damage, battles free radicals, and maintains the integrity of cell membranes . Take Vitamin E to avoid impaired balance and coordination, muscle weakness, and pain and numbness in the limbs — all signs of extreme deficiency . Vitamin E comes in eight different forms, all of which are derived from plants. The eight E’s are divided into two classes:

  • The tocopherols consist of 4 types of vitamin E, alpha, beta, gamma, and delta. The features distinguishing each are slight chemical differences (location and number of methyl groups) on its core structure.
  • The tocotrienols are virtually identical to the tocopherols in structure, except for the presence of 3 unsaturated bonds (hence trienol). Alpha, beta, gamma and delta tocotrienols are more permeable to cell membranes because of their unsaturated bonds. This chemical difference imparts certain advantages over the less permeable tocopherols.

The most potent antioxidant of the group is alpha tocopherol. For reasons still unknown, this form of E represents the bulk of vitamin E present in our serum. This is puzzling, since the plants we normally consume contain much more gamma tocopherol. Scientists originally speculated that our bodies require high serum levels of alpha tocopherol and have developed mechanisms to retain it. Thus, multi-vitamins almost always contain alpha tocopherol. It is becoming more evident, however, that all forms of E are important and that they serve very different functions. Laboratory experiments have indicated that gamma and alpha tocopherol may complement one another with respect to antioxidant protection. Alpha tocopherol is most effective at neutralizing oxygen-based free radicals, whereas gamma tocopherol does best with nitrogen-based free radicals. Both types of radicals are destructive to our bodies. The vitamin E offered on the market is either man-made or isolated from plants. Man-made (or synthetic) vitamin E is designated on the bottle’s label as DL alpha tocopherol. The D and L are isomers or mirror images of each other. Only the D form is representative of the natural vitamin E alpha tocopherol. There is considerable controversy as to whether the L form interferes with the natural D form in the body. Some researchers believe it may be toxic.

Natural vitamin E is usually labeled D alpha tocopherol but almost always contains all 4 tocopherols. Typically, the bottle’s label mentions only D alpha tocopherol because of the expense the manufacturer would incur to assay for the presence and quantity of the other three. The 4 tocopherols are derived from soybean oil or, less commonly, wheat germ. The 4 tocotrienols are usually prepared from extracts of palm oil or rice bran.  Vitamin E deficiency is not common, but it can occur with poor nutrition and/or a problem with absorption of fats. The RDA for vitamin E is 30 International Units (IU) per day for DL and 22 IU/day for D alpha tocopherol. A diet totally devoid of fats can result in a deficiency of E, since some fat is required for absorption from the intestines. Fragile red blood cells are a common characteristic of E deficiency. Blood cell membranes, normally protected by E, tend to oxidize and rupture easily. Recent studies indicate vitamin E may help in slowing cognitive decline in Alzheimer’s patients, and it may even lower blood pressure and cholesterol levels. Significant evidence also supports the vitamin as important for protecting tissues from the destructive action of oxidants and consequent disease, including heart disease, cataracts, cancer, neurological disorders and disorders of the muscular system. The incidence of these diseases increases with age. Thus it is important to obtain enough E to attenuate the age-associated destructive process.

Vitamin E is more than an antioxidant. Growing evidence supports specific roles for the different forms of vitamin E. For example, recent research demonstrates gamma tocopherol to be capable of blocking the activity of an enzyme involved in producing cellular mediators of inflammation (prostaglandins), which can lead to disease. Other tocopherols, including the more popular alpha, are largely ineffective in this context. Alpha tocotrienol has now been shown in cell culture experiments to protect cells of the nervous system from the degenerative action created by the overproduction of the neurotransmitter, glutamate. This chemical, better known as monosodium glutamate, is used as a food enhancer and is infamous for its reputation as the agent responsible for the Chinese restaurant syndrome (bad headaches, etc.) in those who consume too much of it. Normally, an excess of this neurotransmitter activates a neurotoxic enzyme (12-LOX). Tocotrienol, in very small amounts, stops this toxic enzyme in its tracks, thus potentially protecting the nervous tissue.

What You Need: 15 mg per day

Sources:  olive oil (1.9 mg per tablespoon), canola oil (2.4 mg per tablespoon), almonds (7.4 mg per ounce), avocados (2.7 mg per avocado), and hazelnuts (4.3 mg per ounce).

What’s Too Much: 1,000 mg

Vitamin Conversion charts 

Vitamin A: 1 IU is the biological equivalent of 0.3 mcg retinol, or of 0.6 mcg beta-carotene
Vitamin C: 1 IU is 50 mcg L-ascorbic acid
Vitamin D: 1 IU is the biological equivalent of 0.025 mcg cholecalciferol or ergocalciferol
Vitamin E: 1 IU is the biological equivalent of about 0.67 mg d-alpha-tocopherol, or 0.9 mg of dl-alpha-tocopherol.