Vitamin E compounds are a group potent antioxidants. Vitamin E deficiency causes hemolytic anemia and neurologic deficit diseases.
AdvertisementsVitamin E compounds protect the polyunsaturated fatty acids in cellular membranes from lipid peroxidation. Vitamin E deficiency causes fragility and degeneration of cell membranes including those of red blood cells, peripheral axons and posterior column neurons. α-Tocopherol is the most biologically active form of vitamin E.
Dietary vitamin E deficiency is prevalent in developing countries. In developed countries, vitamin E inadequacy arises usually due to fat malabsorption diseases. Vitamin E deficiency is diagnosed by measuring the ratio of plasma alpha-tocopherol to total plasma lipids. A low ratio indicates its deficiency. Taking dietary sources, oral supplements and fortified foods may correct the deficiency.
Functions of vitamin EVitamin E is involved in several physiological and biochemical functions in the body. Tocopherols and tocotrienols function as potent antioxidants, protecting the cellular membranes from oxidative damage.
Vitamin E also has effect on gene expression and it downregulate the expression of the CD36 scavenger receptor gene. It also modulates expression of the connective tissue growth factor (CTGF), responsible for repair and regeneration. alpha-Tocopherol also has functions such as inhibition of platelet aggregation, enzymatic activity regulation and upkeeping neurological health.
Vitamin E deficiency causesDietary vitamin E inadequacy is very rare, except in places where poverty related malnutrition is prevalent. Certain conditions like preterm birth, genetic defective liver metabolism, surgical removal of part or all of the stomach, gastric bypass or total parenteral nutrition may cause the insufficiency. Diseases causing fat malabsorption, such as Bassen-Kornzweig syndrome, Crohn's disease, liver disease, chronic cholestatic hepatobiliary disease, pancreatic insufficiency, pancreatitis, short bowel syndrome, and cystic fibrosis are known to cause chronic inadequacy of the alpha-tocopherol in the system.
Vitamin E deficiency symptomsSome of the symptoms of reduced levels of alpha-tocopherol are:
some forms of spinocerebellar ataxia,
- general ataxia,
- peripheral neuropathy,
- retrolental fibroplasia in infants,
- paralysis of extraocular muscles,
- Skeletal muscle weakness,
- muscular pains,
- muscle weakness,
- muscle atrophy,
- absence of deep tendon reflexes,
- loss of vibratory sensation,
- loss of proprioception,
- deficits in interjoint coordination,
- positive Babinski sign,
- depressed immune response,
- loss of hair,
- hemolysis and erythrocyte destruction,
- impotency and
- male infertility.
Vitamin E deficiency diagnosisNormal the plasma alpha-tocopherol level is 5 to 20 μg/mL (11.6 to 46.4 µmol/L). Levels below 5 μg/mL (less than 11.6 µmol/L) indicate inadequacy. Below normal levels of vitamin E in the serum can determined by analyzing and measuring the alpha-tocopherol : total plasma lipids ratio. A low ratio is indicative of insufficiency of the nutrient in the body.
Vitamin E deficiency diseasesAs said earlier, these group of nutrients have a major function as antioxidants. Cellular membranes have polyunsaturated fatty acids. Free radicals produced during the metabolic processes can damage the cell membranes by the lipid peroxidation of these fatty acids. With the damage to the cell membrane cells become fragile, especially red blood cells and nerve cells.
Neuromotor manifestationsIn patients with low alpha-tocopherol levels, neuromotor symptoms manifest initially with hyporeflexia. It is followed by ataxia, decreased proprioception, decreased vibratory sense, profound muscle weakness, distal muscle weakness, dysphagia, dysarthria, cardiac arrhythmias and dementia.
Cellular damagesProlonged low alpha-tocopherol levels can cause damage and fragility to the cell membranes of the red blood cells. The RBC may rupture and release the contents. The destruction of RBC leads to hemolytic anemia. Low serum levels of vitamin E promotes platelet adhesion. Prolonged low alpha-tocopherol levels of inhibits lymphocyte proliferation and increases the production of immunosuppressive prostaglandin.
Visual impairmentProlonged low serum vitamin E levels can cause retinopathy, detached retina, pigmented retinopathy, damage to accessory visual structures, uveitis, misalignment of eyes (strabismus), long-tract defects, visual-field constriction, ophthalmoplegia, limitation in upward gaze, limited upward-gaze nystagmus, dissociated nystagmus, nyctalopia (night blindness) and total blindness.
Ataxia with vitamin E deficiency (AVED)Ataxia with vitamin E deficiency (AVED) is a rare, inherited autosomal recessive neurodegenerative disease. When the dietary and supplemental vitamin E is absorbed and delivered to the liver, only alpha-tocopherol is preferentially recognized by the alpha-tocopherol transfer protein (alpha-TTP). The α-tocopherol transfer protein gene (TTPA) expression leads to alpha-TTP production. The liver secretes only alpha-tocopherol into blood plasma. The other forms are removed from the circulation by metabolism, conjugation and excretion.
Any pathogenic mutations in the TTPA gene will affect the activation of αTTP protein and also transfer and distribution of alpha-tocopherol to cells and tissues throughout the body. The clinical manifestations include, a gradually progressing ataxia, gait ataxia (unsteady, staggering gait), paresis of ankle dorsiflexion (dropping of the forefoot) truncal and extremity ataxia, dysarthria (slurring of speech), muscle weakness, limitation in upward gaze, absence of neurologic reflexes, inverted plantar responses, pes cavus (high arched foot), severe sensory neuropathy, head titubation (reeling head) and tetraplegia (total loss of limb movement). If detected early, by administering large doses of vitamin E supplements we can keep the patient going as well as increase the quality of his life.
Abetalipoproteinemia (Bassen-Kornzweig syndrome)Abetalipoproteinemia is a rare autosomal recessive disease, caused by a mutation in microsomal triglyceride transfer protein (MTP) gene. The mutation results in absence of the apolipoproteins B-48 and B-100 which affects the absorption of dietary fats, cholesterol and fat-soluble vitamins A, D, E, and K. The consequences are, poor growth rate, fatty diarrhea, poor muscle coordination, ataxia, progressive damage to the retina and near-blindness. Administering massive doses of vitamin E may restore the body health and help in producing lipoproteins.
Vitamin E sourcesAnimal fats, liver and eggs are good sources of vitamin E. Almonds, walnuts, vegetable oils, sunflower seeds, green leafy vegetables, tomatoes, sweet potatoes and asparagus are rich plant sources of vitamin E. In patients with malabsorption, α-tocopherol injections are required to overcome the defect of absorption and transport. Please note that high doses of vitamin E along with coumarin or warfarin may increase the risk of bleeding and hemorrhagic stroke.
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