Vitamin E

Is vitamin E safe?

From food, yes. Nuts, seeds and vegetable oils supply the 15 mg a day adults need, and nobody has found harm from that. High-dose capsules are a different product. The standard 400 IU and 1,000 IU pills contain 12 to 45 times the daily requirement, and the large trials that tested them found more harm than benefit for healthy people.

The two numbers to know: in the SELECT trial, 400 IU a day raised prostate cancer by 17%; across nine trials, vitamin E raised the risk of a bleeding stroke by 22%. Neither is a huge absolute risk, but both appeared at doses millions of people take.

Which upper limit is right: 1,000 mg or 300 mg?

The two main authorities disagree by more than three times. The US National Academies set the upper limit at 1,000 mg a day of supplemental alpha-tocopherol, which is 1,500 IU of natural (d-alpha) or 1,100 IU of synthetic (dl-alpha) vitamin E. The European Food Safety Authority set 300 mg a day and reviewed it again in 2024. EFSA found no new data to change it and kept it.

Both limits rest on the same effect: vitamin E interferes with blood clotting. The gap is in how much safety margin each body applied. In practice, a 1,000 IU capsule of natural vitamin E (670 mg) is fine by the US limit and more than twice the European one. EFSA also stated that its limit does not apply to people on anticoagulant or antiplatelet drugs, including aspirin, or to people treated for heart disease.

The units confuse many buyers. 1 IU of natural vitamin E is 0.67 mg; 1 IU of synthetic is 0.45 mg. A "400 IU" capsule can therefore hold anything from 180 to 268 mg.

What the big trials found

Vitamin E was once expected to prevent heart disease and cancer. The trials that tested it at scale point the other way.

The mortality signal is the least certain of the three. The high-dose trials in the 2005 analysis were often small and mostly in people who were already ill, and a later meta-analysis of 46 trials with 171,244 people found no significant effect on deaths. The Linus Pauling Institute also notes a re-analysis in which the higher death rate was significant only at 2,000 IU a day, above the US upper limit. The prostate cancer and bleeding stroke findings come from large randomised trials and are harder to dismiss. The HOPE and GISSI heart trials also reported more heart failure on vitamin E.

Does vitamin E harm the liver?

No. LiverToxLiverToxA free US National Institutes of Health database that summarises what is known about liver injury caused by medicines, herbs and supplements.More in the glossary, the US government database of drug-induced liver injuryDrug-induced liver injuryLiver damage caused by a medicine, herbal product or supplement. It is usually rare and unpredictable, but it can be serious.More in the glossary, says there is no evidence that vitamin E causes liver injury or jaundice, even at very high doses. Doctors sometimes prescribe 800 IU a day for fatty liver disease with inflammation (MASH) in people without diabetes, after the PIVENS trial found it improved liver biopsies. That is a medical treatment with monitoring, not a reason to self-dose.

Blood thinners and other interactions

The interaction that matters is bleeding. Vitamin E makes platelets less sticky, and at high doses it interferes with vitamin K. In a study of healthy adults, 1,000 IU a day for 12 weeks reduced activation of prothrombin, a vitamin K-dependent clotting protein.

That adds to the effect of warfarin, heparin, clopidogrel, aspirin and other NSAIDs. People with bleeding disorders, a past bleeding stroke or vitamin K deficiency should not take vitamin E supplements without medical advice.

One less obvious interaction: in a three-year trial in 160 people with heart disease, an antioxidant mix that included 800 IU of vitamin E reduced the protective effect of simvastatin plus niacin. Ask your oncologist before taking antioxidants during chemotherapy or radiotherapy.

Do the capsules contain what they say?

Mostly. ConsumerLab's 2020 review of 17 vitamin E products, including oils and creams, found three off-label: one held less than 1% of its claimed vitamin E, one 88% and one 65% more than stated. A 2010 university test of vitamin E succinate products found 0% to 130% of the label, and two contained a different form.

Vitamin E acetate also has a darker history. It was the additive most strongly linked to the 2019 to 2020 outbreak of vaping lung injury (2,807 hospital cases or deaths in the US), almost all from THC cartridges. The CDC notes that the same compound usually causes no harm when swallowed in a supplement or applied to skin.

Who should be careful

• People on blood thinners or aspirin: talk to your doctor before taking any vitamin E supplement.
• Before surgery: some doctors ask patients to stop high-dose vitamin E two to four weeks ahead.
• Men worried about prostate cancer: SELECT is a reason to avoid high-dose vitamin E unless prescribed.
• Anyone taking a multivitamin as well: add up the vitamin E from all products.

If you do take it, choose a product with independent testing (USP VerifiedThird-party testingTesting of a supplement by an independent lab to check that it contains what the label says and is free of set contaminants.More in the glossary or similar), check whether the label says d-alpha (natural) or dl-alpha (synthetic), and ask your doctor or pharmacist what dose, if any, makes sense for you.

How we scored it

Organ toxicity (75) and regulatory record (85) are reasonable: no liver harm in LiverToxLiverToxA free US National Institutes of Health database that summarises what is known about liver injury caused by medicines, herbs and supplements.More in the glossary and no bans. Dose safety (52) is the weakest factor, because randomised trials found more prostate cancer and bleeding strokes at the common 400 IU dose. We keep it just above 50 rather than lower because that dose is under both upper limits and the extra risks are small; niacin (45) is lower because common products exceed its limit several times over. Interactions (62) reflect the added bleeding risk with blood thinners, and quality (70) a few products far off their label.