Is 400 mg of vitamin E daily too much? What You Need to Know

October 28, 2025 •

3 min read

According to the National Institutes of Health, the Recommended Dietary Allowance (RDA) for adults is 15 mg of vitamin E daily. Given this, many people wonder, "is 400 mg of vitamin E daily too much?" The answer is more complex than a simple yes or no.

Quick Summary

While a 400 mg dose is below the 1,000 mg Tolerable Upper Intake Level, it significantly exceeds the average adult's recommended daily intake. Long-term supplementation at this level, particularly with synthetic forms, is associated with potential health risks, and most healthy individuals do not need it.

Key Points

RDA is 15 mg, not 400 mg: The Recommended Dietary Allowance for adults is a mere 15 mg, making 400 mg a substantially higher dose.
Risks outweigh benefits for healthy people: For the average healthy person, the potential risks of a 400 mg vitamin E supplement generally outweigh the unproven benefits.
Blood-thinning effects are a major concern: High doses of vitamin E can thin the blood, increasing the risk of serious bleeding and hemorrhagic stroke, especially in those on blood thinners.
Synthetic form linked to prostate cancer: Studies have shown a link between high-dose synthetic vitamin E (dl-alpha-tocopherol) and an increased risk of prostate cancer in men.
Natural food sources are safest: Most people can obtain sufficient vitamin E from food sources like nuts, seeds, and oils without the risks associated with high-dose supplements.
Consult a doctor before supplementing: Always discuss high-dose vitamin E supplementation with a healthcare provider to understand your specific needs and potential risks.

Understanding Vitamin E: RDA vs. UL

It's important to understand the difference between the Recommended Dietary Allowance (RDA) and the Tolerable Upper Intake Level (UL) for vitamin E. The RDA is the daily amount recommended for most healthy people, which is 15 mg for adults. The UL is the maximum daily intake considered unlikely to cause adverse effects, set at 1,000 mg for adults from supplements.

While 400 mg is below the UL, it's over 26 times the RDA. This significant difference raises questions about safety and necessity, particularly with prolonged use and for certain individuals.

Potential Risks Associated with High-Dose Vitamin E

Increased Bleeding Risk

A notable risk of taking high amounts of vitamin E is its potential to thin the blood. High doses can affect blood clotting, increasing the risk of serious bleeding, including in the brain. This risk is higher for those on blood-thinning medications. Doses over 300 mg daily have been linked to potential interactions.

Increased Mortality Concerns

Some research reviews suggest a possible link between high-dose vitamin E (400 IU or more daily) and a small increase in the risk of death from any cause. These findings highlight the lack of proven benefits and potential harm of high doses.

Prostate Cancer Link

A study called SELECT found that men taking 400 IU (180 mg) of synthetic vitamin E daily had a higher risk of developing prostate cancer. This led to the study being stopped and serves as a caution against unnecessary high-dose synthetic vitamin E.

Other Potential Side Effects

Taking very high doses of vitamin E can also cause less serious side effects like nausea, fatigue, headache, dizziness, and diarrhea, which usually go away after stopping the supplement.

Natural vs. Synthetic Vitamin E: A Key Distinction

Vitamin E comes in natural (d-alpha-tocopherol) and synthetic (dl-alpha-tocopherol) forms. Natural vitamin E is found in foods and is more potent and better absorbed than the synthetic version found in many supplements.

Comparison of Vitamin E Forms


Feature	Natural Vitamin E (d-alpha-tocopherol)	Synthetic Vitamin E (dl-alpha-tocopherol)
Source	Plant-based foods (oils, nuts, seeds)	Laboratory-made
Potency	More biologically active and potent	Less potent; requires higher mg dose for same effect
Absorption	Better absorbed and utilized by the body	Poorly absorbed compared to natural form
Labeling	Often listed as "d-alpha-tocopherol"	Often listed as "dl-alpha-tocopherol"
IU Conversion	1 IU $\approx$ 0.67 mg	1 IU $\approx$ 0.45 mg

It's worth noting that the SELECT study linked synthetic vitamin E to increased prostate cancer risk. Some supplements contain various forms of vitamin E, and their combined effects are not fully understood.

Who Needs Vitamin E Supplements?

Most healthy adults can get enough vitamin E from their diet by eating foods like vegetable oils, nuts, seeds, and green vegetables. Supplements are usually for individuals with conditions causing vitamin E deficiency. Discuss any high-dose supplementation with a healthcare provider.

Conclusion: The Final Verdict on 400 mg

For most healthy people, a daily dose of 400 mg of vitamin E is likely too much. It significantly exceeds the recommended intake and carries potential risks like increased bleeding and, with synthetic forms, a link to prostate cancer. Prioritize getting vitamin E from a healthy diet and consult your doctor before taking high-dose supplements. Additional information on vitamin E and supplements is available from the NIH Office of Dietary Supplements.

This content is for informational purposes only and does not constitute medical advice.

Risk Factors to Consider

Medical History: Conditions like heart disease or stroke.
Medications: Taking blood thinners.
Gender: Men have shown a potential increased risk of prostate cancer with high-dose synthetic vitamin E.
Dietary Intake: Already consuming a high amount of vitamin E from food.
Supplement Form: Synthetic dl-alpha-tocopherol has been associated with more negative outcomes in studies.

Frequently Asked Questions

No, 400 IU is not the same as 400 mg. The conversion depends on the form of vitamin E. For natural vitamin E (d-alpha-tocopherol), 400 IU is about 268 mg. For synthetic vitamin E (dl-alpha-tocopherol), 400 IU is approximately 180 mg.

Some early signs of excessive vitamin E intake include milder symptoms like nausea, fatigue, headache, and diarrhea. If you experience these, it's advisable to stop taking the supplement and consult a doctor.

While high doses of vitamin E can affect blood clotting, its direct impact on blood pressure is less documented. The main cardiovascular risk is an increased chance of hemorrhagic stroke due to blood thinning.

For most healthy people, long-term daily use of 400 mg of vitamin E is not recommended and is not necessary. Any high-dose supplementation should be guided by a healthcare professional based on a diagnosed deficiency.

The best food sources for vitamin E include vegetable oils (especially wheat germ and sunflower), nuts like almonds and sunflower seeds, and green leafy vegetables such as spinach and broccoli.

Topical application of vitamin E, often used for skin health, generally carries fewer systemic risks than high-dose oral supplementation. However, topical use does not provide the same benefits as dietary intake, and some individuals may experience skin irritation.

Combining high-dose vitamin E with other antioxidant supplements is not advised without medical supervision. Some studies have shown that antioxidant supplements can interfere with the effectiveness of certain medications and therapies.