Biomarker µmol/l (mg/l)

Vitamin E (Tocopherol)

Fat-soluble antioxidant protecting cell membranes from oxidative stress

Also known as

α-tocopherol tocopherol vitamin E complex tocotrienol

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

Agree on your personal target range with your doctor.

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 amounts of α-tocopherol can potentiate anticoagulant effects (vitamin K antagonism), prolong bleeding time, and paradoxically increase oxidative stress. The tolerable upper intake level was set in 2003 by the EU Scientific Committee on Food (SCF), EFSA's predecessor; EFSA re-evaluated it in 2024 (adopted on 28 June, published on 2 August 2024) and retained it for the existing age groups. The critical endpoint is blood clotting with an increased risk of bleeding. It does not apply to people on anticoagulant or antiplatelet medicines, on secondary prevention of cardiovascular disease or with vitamin K malabsorption. It is a safety limit, not an intake recommendation.

✓ What can influence this value

The vitamin E level is influenced by intake from food (wheat germ oil has the highest content, followed by sunflower oil, almonds, hazelnuts, spinach, avocados) and by supplements, which raise the value. Because vitamin E is fat-soluble and absorbed together with fat, fat metabolism disorders, malabsorption (Crohn's disease, celiac disease, cystic fibrosis), bile acid deficiency, and very low-fat diets can lower the value. The assessment is made by the treating doctor.

When to test

Reasons for a measurement can include malabsorption syndromes, unexplained neurological symptoms, hemolytic anemia in newborns, or a severely fat-restricted diet. Whether and when it is measured is decided by your doctor.

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 than synthetic dl-α-tocopherol (all-rac-α-tocopherol). The natural form is identifiable by the 'd-' prefix.

What role does vitamin E play in 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 high-dose α-tocopherol; the evidence base is not conclusive. Whether and how treatment is given is decided by your doctor.

Vitamin E (Tocopherol)

Sources

Last updated: May 28, 2026

This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.