Vitamin E has many biological functions, the antioxidant function being the most important and best known. The α-isomer is the most active biologic form of Vitamin E. The γ-isomer is the most active outside the body and is widely added to pet food to prevent lipid oxidation.
Vitamin E is used in nutrition to prevent or treat many diseases caused by oxidative stress in the cell (physical effort, pollution) and caused by ageing (cardiovascular diseases, cataracts, degenerative neurological diseases).
Vitamin E was discovered in 1920 as a factor in fertility and it was isolated in 1936. It was not until the eighties that its major antioxidant role for the cell was proven. Vitamin E is a generic term that covers several substances, of which alphatocopherol is the most widespread and the form that is the most active biological antioxidant in the cell membranes. Vitamin E is stored in the body’s fat tissue, in the liver and in the muscles.
Vitamin E is a fat-soluble vitamin that is transported around the body in lymph and blood vessels bound to lipoproteins.
Vitamin E protects the cell against the action of free radicals. More properly known as “oxygen-reactive species,” free radicals are natural products of the cells during biological oxidation. They are normally part of the body’s natural defences, but when the balance between antioxidants and free radicals is disrupted, the result is oxidative stress.
Generally speaking, vitamin E helps :
Signs of Vitamin E deficiency are mostly attributed to membrane dysfunction as a result of oxidative damage. Clinical signs in dogs include muscle weakness, reproductive disorders, and gestational failure. In cats, clinical signs include heart and skeletal muscle dysfunction and hepatitis.
Vitamin E is synthesised only by plants with highest concentrations in green leaves. The richest sources of Vitamin E are vegetable oils, and to a lesser extent seeds and cereal grains.