Alpha-Tocopherol (Vitamin E)
Alpha-tocopherol in Serum
Vitamin E is a fat-soluble vitamin that have eight naturally occurring chemical forms, among which only alpha-tocopherol meets human nutritional requirements1.
As an antioxidant, it protects the body against free radicals by preventing production of reactive oxygen species (ROS) when fat is oxidized. It also regulates gene expression and is important for immune function2.
Signs and Symptoms of Deficiency or Toxicity
Vitamin E deficiency does not typically occur among healthy individuals. Rather it is caused by fat malabsorption syndromes1.
Deficiency states are associated with certain diseases causing peripheral neuropathy, ataxia, skeletal myopathy, retinopathy, and reduced immune response1,2.
Excessive vitamin E intakes may lead to hemorrhage and the inhibition of platelet aggregation1.
Biomarker and Methods of Analysis
ALPHA-TOCOPHEROL IN SERUM
Alpha-tocopherol is the major form of vitamin E in the blood circulation. This fat soluble vitamin is the form of vitamin E selectively transported via VLDL (very low density lipoprotein) from the liver.
It is the most preferred and commonly used method to assess Vitamin E level in the body because of ease in measurement and because it is the major form circulating in the body3.
No established guidelines for supplementation of the general public. However, an intake of 400 IU/day is an acceptable intake for lowering the susceptibility of LDL to oxidation4.
Following are the upper limits for vitamin E intakes5.
- For children
- 1-3 y.o: 200 mg
- 4-8 y.o.: 300 mg
- 9-13 y.o.: 600 mg
- 14-18 y.o.: 800 mg
- For adults, 19 years and older: 1000 mg/day
- For pregnant and lactating women who are 14-18 years: 800 mg and for those older, 1000 mg/day
Vitamin E can inhibit platelet aggregation and cause bleeding when taken concurrent with anti-blood clotting medications2.
Best sources are vegetable oil such as sunflower and safflower oil. Corn and soybean oil are also good sources. Green vegetables like spinach and broccoli contain some vitamin E. May also be found in fortified food products.
(1) Office of Dietary Supplements- National Institutes of Health. (n.d.) Vitamin E. Fact Sheet for Health Professionals. Retrieved from https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/
(2) Office of Dietary Supplements- National Institutes of Health. (May 9, 2016). Vitamin E. Fact Sheet for Consumers. Retrieved from https://ods.od.nih.gov/factsheets/VitaminE-Consumer/
(3) Gibson, R.M. (2005). Principles of Nutritional Assessment. New York: Oxford University Press, Inc.
(4) Vitamin E Research and Information Service. (n.d.). The Free Radical School. Tocopherol (Vitamin E) in Health and Disease. Retrieved from https://sfrbm.org/site/assets/documents/frs/VerisTOH.pdf.
(5) Philippine Dietary Reference Intakes. 2015. Department of Science Technology-Food and Nutrition Research Institute.