Vitamin E (Tocopherol)
Fat-soluble antioxidant protecting cell membranes from oxidative stress
Also known as
Definition
Vitamin E is a collective term for eight fat-soluble compounds (four tocopherols, four tocotrienols). α-Tocopherol is the most biologically active form in the human body. As a lipid-soluble antioxidant, vitamin E protects cell membranes, LDL particles, and polyunsaturated fatty acids from oxidative damage. It modulates immune function, inflammatory responses, and thrombotic processes.
| Parameter | Value |
|---|---|
| Unit | µmol/l (mg/l) |
| Reference Range | 12–42 µmol/l (5–18 mg/l) α-tocopherol in serum |
| Optimal Range (lab2go) | 23–35 µmol/l (10–15 mg/l) (lab2go Optimum Zone; optimal antioxidant protection) |
Conversion: 1 µmol/l α-tocopherol = 0.431 mg/l. Reference ranges often given in mg/l (normal: 5–20 mg/l).
↓ What a low value means
Vitamin E deficiency is rare but occurs with fat metabolism disorders, malabsorption (Crohn's disease, celiac disease, cystic fibrosis), bile acid deficiency, or very low-fat diets. Symptoms: peripheral neuropathy, ataxia, muscle weakness, hemolysis (in newborns), increased susceptibility to oxidative stress.
↑ What a high value means
High vitamin E levels result from supplementation. Very high doses (> 1000 mg/day α-tocopherol) can potentiate anticoagulant effects (vitamin K antagonism), prolong bleeding time, and paradoxically increase oxidative stress. EFSA sets the tolerable upper level at 300 mg/day.
✓ How to optimize this marker
Dietary sources: wheat germ oil (highest content), sunflower oil, almonds, hazelnuts, spinach, avocados. Supplementation: 15 mg/day α-tocopherol (DGE reference value). When supplementing: prefer mixed tocopherols over isolated synthetic dl-α-tocopherol. Fat-soluble — take with a fat-containing meal.
When to test
With malabsorption syndromes, unexplained neurological symptoms, hemolytic anemia in newborns, or as baseline diagnostics with severely fat-restricted diets. Routine screening is not recommended.
Frequently asked questions
Does vitamin E protect against heart disease? +
Early observational studies showed protective effects, but large randomized trials (HOPE, GISSI) did not demonstrate cardioprotective benefit from isolated α-tocopherol. There are indications that tocotrienols and mixed tocopherols may be more effective than isolated α-tocopherol.
What is the difference between natural and synthetic vitamin E? +
Natural d-α-tocopherol (RRR-α-tocopherol) has higher biological activity (~2-fold) than synthetic dl-α-tocopherol (all-rac-α-tocopherol). The natural form is identifiable by the 'd-' prefix. For most preventive purposes, natural vitamin E from whole foods or mixed tocopherols is preferable.
Can vitamin E help with Alzheimer's disease? +
Some studies suggest slowed cognitive decline with high vitamin E levels. One trial (JAMA 2014) showed slowing of functional decline in Alzheimer's disease with 2000 IU/day α-tocopherol. The American Academy of Neurology (AAN) suggests it as an option, but the evidence base is not conclusive.
Sources
Last Reviewed: May 28, 2026 · sina
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.