Vitamin E

Absorption

10-33% of deuterium labelled vitamin E is absorbed in the small intestine. Absorption of Vitamin E is dependant upon absorption of the fat in which it is dissolved. For patients with poor fat absorption, a water soluble form of vitamin E may need to be substituted such as tocopheryl polyethylene glycol-1000 succinate.
In other studies the oral bioavailability of alpha-tocopherol was 36%, gamma-tocotrienol was 9%. The time to maximum concentration was 9.7 hours for alpha-tocopherol and 2.4 hours for gamma-tocotrienol.

Toxicity

There is no data available for effects in pregnancy, breast feeding, hepatic impairment, or renal impairment. However, it appears that the process of vitamin E elimination is strict and self regulating enough that vitamin E toxicity is exceedingly rare. Studies showing adverse effects from excess vitamin E generally involve people consuming more than 1000mg/day for weeks to months.

Description

(+)-α-Tocopherol is one of eight components of vitamin E and, while not the most abundant, it is the most biologically active. It occurs naturally in many foods, especially in plant oils such as wheat germ, canola, sunflower, and safflower.
In 1936, Herbert M. Evans*, Oliver H. Emerson, and Gladys A. Emerson at the University of California, Berkeley, reported the first isolation of α-tocopherol, from wheat germ. Vitamin E was already known, and these authors established that α-tocopherol is its active component. Between 1938 and 1943, the same team published seven papers on the compound’s role in nutrition.
Also in 1938, Erhard Fernholz at Merck (Rahway, NJ) described the structure of α-tocopherol, which he deduced from its degradation products. The same year, three other research groups reported syntheses of the molecule: Paul Karrer et al. at the University of Zurich, Franz Bergel et al. at the University of Manchester (UK), and Lee Irvin Smith et al. at the University of Minnesota (Minneapolis). Five years later, Smith and Joseph A. Sprung followed up with an improved synthesis.
The main biological function of vitamin E/α-tocopherol is as a fat-soluble antioxidant. The US National Academy of Medicine’s adult daily dietary recommendation for vitamin E is 15 mg; individuals with deficiencies are often prescribed the vitamin as a supplement. Vitamin E is also added to commercial fats and oils as an antioxidant.
During this National Chemistry Week, “The Healing Power of Chemistry”, keep in mind how α-tocopherol keeps your body safe.

The Uses of Vitamin E

vitamin E, antioxidant

What are the applications of Application

(+)-α-Tocopherol is a fat-soluble antioxidant

Background

In 1922, vitamin E was demonstrated to be an essential nutrient. Vitamin E is a term used to describe 8 different fat soluble tocopherols and tocotrienols, alpha-tocopherol being the most biologically active. Vitamin E acts as an antioxidant, protecting cell membranes from oxidative damage. The antioxidant effects are currently being researched for use in the treatment of diseases causing bone loss, cardiovascular diseases, diabetes mellitus and associated comorbidities, eye diseases, inflammatory diseases (including skin conditions), lipid disorders, neurological diseases, and radiation damage. Though this research is so far inconclusive, vitamin E remains a popular supplement and is generally considered safe by the FDA.

Indications

Vitamin E supplementation is indicated for treatment of vitamin E deficiency which can occur in cystic fibrosis, cholestasis and severe liver disease, abetalipoproteinemia or simply poor diet.

Pharmacokinetics

Vitamin E is a collective term used to describe 8 separate fat soluble antioxidants, most commonly alpha-tocopherol. Vitamin E acts to protect cells against the effects of free radicals, which are potentially damaging by-products of the body's metabolism. Vitamin E deficiency is seen in persons with abetalipoproteinemia, premature, very low birth weight infants (birth weights less than 1500 grams, or 3? pounds), cystic fibrosis, and cholestasis and severe liver disease. Preliminary research suggests vitamin E may help prevent or delay coronary heart disease and protect against the damaging effects of free radicals, which may contribute to the development of chronic diseases such as cancer. It also protects other fat-soluble vitamins (A and B group vitamins) from destruction by oxygen. Low levels of vitamin E have been linked to increased incidence of breast and colon cancer.

Metabolism

Alpha and gamma tocopherol are undergo beta oxidation and a process mediated by cytochrome P450s such as CYP4F2, CYP3A4, and CYP3A5. These processes convert alpha and gamma tocopherol to alpha-CEHC (2,5,7,8-tetramethyl-2-(2’-carboxyethyl)-6-hydroxychroman) and gamma-CEHC (2,7,8-trimethyl-2-(2’-carboxyethyl)-6-hydroxychroman) respectively, however the full process is not known.