Vitamin E deficiency

Vitamin E deficiency causes nerve problems due to poor conduction of electrical impulses along nerves due to changes in nerve membrane structure and function.

Signs and symptoms

Signs of vitamin E deficiency include the following:

• Neuromuscular problems-such as spinocerebellar ataxia and myopathies.^[1]
• Neurological problems-may include dysarthria, absence of deep tendon reflexes, loss of vibratory sensation and proprioception, and positive Babinski sign.^[1]
• Anemia-due to oxidative damage to red blood cells^[1]
• Retinopathy^[2][3][4]
• Impairment of the immune response^[2][3][4]

There is also some laboratory evidence that vitamin E deficiency can cause male infertility.^[1]

Causes

Vitamin E deficiency is rare and is almost never caused by a poor diet.^[1] Instead, there are three specific situations when a vitamin E deficiency is likely to occur:^[5]

• Premature, very low birth weight infants - birth weights less than 1500 grams, or 3.5 pounds. A neonatologist, a pediatrician specializing in the care of newborns, typically evaluates the nutritional needs of premature infants.
• Rare disorders of fat metabolism - There is a rare genetic condition termed isolated vitamin E deficiency or ataxia with isolated with vitamin E deficiency, caused by mutations in the gene for the tocopherol transfer protein.^[6] These individuals have an extremely poor capacity to absorb vitamin E and develop neurological complications that are reversed by high doses of vitamin E.
• Fat malabsorption - Some dietary fat is needed for the absorption of vitamin E from the gastrointestinal tract. Anyone diagnosed with cystic fibrosis, individuals who have had part or all of their stomach removed or who have had a gastric bypass, and individuals with malabsorptive problems such as Crohn's disease, liver disease or pancreatic insufficiency may not absorb fat (people who cannot absorb fat often pass greasy stools or have chronic diarrhea and bloating). Abetalipoproteinemia is a rare inherited disorder of fat metabolism that results in poor absorption of dietary fat and vitamin E.^[7] The vitamin E deficiency associated with this disease causes problems such as poor transmission of nerve impulses, muscle weakness, and degeneration of the retina that can cause blindness.

Mechanism

• Visual changes-Photoreceptor outer segment membranes have a very high concentration of polyunsaturated fatty acids (PUFA's) and are potentially very susceptible to oxidative damage (the retina consumes 5-10 times more oxygen per milligram than any other tissue tested). Vitamin E is present in the outer segment and is the only well-recognized chain-breaking, lipid-soluble antioxidant in vivo. After 12 months of experimental vitamin E deficiency in rats, visual function was absent or grossly abnormal. There was a 90% loss of DHA from the retina-probably caused by peroxidative degradation-and changes in retinal membrane fluidity.^[8]

Treatment

The treatment is some form of Vitamin E supplementation.

Aggressive vitamin E replacement therapy has been shown to either prevent, halt or improve visual abnormalities.

See also

• Familial isolated vitamin E deficiency
• Tocopherol

References