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What are the effects of vitamin e deficiency

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vitamin E deficiency ataxia neuropathy retinopathy

Vitamin E deficiency is rare in people with a normal gut. It usually comes from problems absorbing or transporting fat, not from a poor diet. Its main effects are neurological, with some effects on blood, muscle and eye.
Who gets it
  • Chronic severe fat malabsorption: cholestatic liver disease, cystic fibrosis, Crohn disease and extensive intestinal resection. A related source also lists primary biliary cholangitis.
  • Abetalipoproteinemia (Bassen-Kornzweig disease).
  • Isolated familial vitamin E deficiency, also called ataxia with vitamin E deficiency (AVED). This is autosomal recessive. Mutations in the α-tocopherol transfer protein gene stop the liver from putting α-tocopherol into VLDL.
  • Low dietary intake alone causes only marginal deficiency, which is generally asymptomatic. - Yamada's Textbook of Gastroenterology, 7th ed.
Clinical effects
  1. Neurological (the dominant feature)
    • Prolonged deficiency of any cause can, after years, cause a spinocerebellar syndrome. It features large-fiber sensory neuropathy, ataxia, loss of proprioception, areflexia and ophthalmoplegia. It can be indistinguishable from Friedreich ataxia. - Bradley and Daroff's Neurology in Clinical Practice, p. 2701
    • In adults with chronic cholestasis, it may take about 2 years to deplete stores and another 5-10 years for neurological complications to appear.
    • The cause is a distal axonopathy of large-caliber sensory axons in peripheral nerves and the posterior columns of the spinal cord. Nerve conduction studies show normal motor conduction and low-amplitude or absent sensory nerve action potentials (SNAPs).
    • Some patients have predominant myopathy or peripheral nerve disease.
    • In primary biliary cholangitis, the deficiency mainly affects the posterior columns. This causes areflexia, loss of proprioception and ataxia. - Sleisenger and Fordtran's Gastrointestinal and Liver Disease
  2. Eye: pigmentary retinopathy and ophthalmoplegia.
  3. Hematologic: hemolytic anemia, because red cell membranes are damaged by oxidation. This is described mainly in children with cystic fibrosis and chronic cholestasis. - Tietz Textbook of Laboratory Medicine, 7th ed.
  4. Immune: vitamin E normally supports T-cell immunity, so deficiency may impair it. - Yamada's Textbook of Gastroenterology
Mechanism: Vitamin E (α-tocopherol) is a fat-soluble antioxidant. It sits in cell membranes and protects lipids from free-radical oxidation. Without it, long-lived and highly oxidative tissues are damaged, namely large sensory axons, the retina and red cells.
Diagnosis
  • A low fasting plasma vitamin E level (below 5 μg/mL) establishes the diagnosis.
  • Levels can look falsely normal in hyperlipidemia, so interpret them against lipid levels.
  • Work up the cause of fat malabsorption: 72-hour fecal fat, vitamin A and D levels, liver function tests, a blood smear for acanthocytes (abetalipoproteinemia), and apolipoprotein B.
Treatment: The textbook passages I read did not cover treatment. Standard practice is to treat the underlying cause and give high-dose vitamin E supplements, but I did not verify doses from the library.
Recent evidence check: A PubMed search of the last 2 years found no recent meta-analysis or systematic review on deficiency itself. The three results were on supplementation (pediatric fatty liver, heart disease, cognition). None contradicts the textbook description above.
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