What is the Tolerable Upper Intake Level of Selenium?

January 9, 2026 •

3 min read

For adults, the U.S. Tolerable Upper Intake Level (UL) for selenium is 400 micrograms (mcg) per day, representing the maximum daily amount considered safe for chronic consumption from all sources. Understanding what is the tolerable upper intake level of selenium is crucial because while essential for health, excessive intake can lead to adverse effects.

Quick Summary

The Tolerable Upper Intake Level (UL) for selenium varies by region and age, with the U.S. adult standard at 400 mcg daily. Chronic intake above the UL can lead to selenosis, a condition with symptoms like brittle hair, nail changes, and a garlic-like breath odor. Excess is most commonly caused by high-dose supplements or over-consumption of Brazil nuts, as the margin between sufficient intake and toxicity is relatively narrow.

Key Points

U.S. Upper Limit: For adults, the Tolerable Upper Intake Level (UL) for selenium is 400 micrograms (mcg) per day from all sources, including food and supplements.
European Standard: The European Food Safety Authority (EFSA) established a more conservative adult UL of 255 mcg/day, reflecting differing regional guidelines.
Selenosis Risk: Chronic intake above the UL can cause selenosis, a condition characterized by tell-tale signs like hair loss, brittle nails, and a garlic-like breath odor.
Supplement Caution: High-dose supplements and frequent consumption of exceptionally rich food sources like Brazil nuts are the most common causes of excessive selenium intake.
Narrow Margin: The gap between the beneficial dose and the toxic dose of selenium is relatively small, emphasizing the importance of not exceeding the UL.
Consult a Doctor: It is always recommended to consult a healthcare provider before taking high-dose selenium supplements to ensure safety and prevent toxicity.
Dietary Intake is Key: The vast majority of people can meet their selenium needs through a balanced diet alone without supplements.

What is the Tolerable Upper Intake Level (UL) of Selenium?

The Tolerable Upper Intake Level (UL) is the highest daily nutrient intake level that is likely to pose no risk of adverse health effects to almost all individuals in the general population. The specific value for selenium can vary depending on the health authority setting the guideline, reflecting differences in dietary habits and environmental factors in different regions. For example, the US and Australia/New Zealand have historically set a higher UL for adults than the European Food Safety Authority (EFSA).

The UL applies to total intake from food, beverages, and dietary supplements. For most people, getting adequate selenium from a balanced diet alone is very safe and rarely poses a risk of toxicity. The risk of exceeding the UL increases significantly with the use of high-dose supplements or the regular, excessive consumption of exceptionally high-selenium foods like Brazil nuts.

Varying ULs Around the World

It's important to recognize that the UL for selenium is not a universal standard. Different international bodies have set varying limits based on their research and population needs. This table provides a comparison of the ULs set by different authorities based on current guidelines:


Age Group	U.S. / Australia/NZ UL (mcg/day)	EU UL (mcg/day)
Adults 19+	400	255
Teens 14-18	400	250
Children 9-13	280	200
Children 4-8	150	90
Children 1-3	90	60
Infants 7-12 months	60	Not Defined (AI used)
Infants 0-6 months	45	Not Defined (AI used)

These differences highlight the importance of considering regional dietary intake and health standards when assessing selenium levels. The more conservative European limits often reflect a lower baseline dietary intake from soil, making supplements a greater risk factor for exceeding the UL.

Symptoms and Risks of Excess Selenium (Selenosis)

Exceeding the tolerable upper intake level of selenium can cause a condition known as selenosis. The line between sufficient and toxic doses is often described as narrow, meaning that long-term, slightly elevated intake can gradually lead to toxicity. Common symptoms of selenosis include a garlic-like breath odor, brittle hair and hair loss, nail changes, and gastrointestinal issues. In severe cases, more serious effects like neurological problems can occur.

Selenium Sources: Food vs. Supplements

A balanced diet is usually sufficient to meet the adult Recommended Dietary Allowance (RDA) of 55 micrograms of selenium per day. Food sources of selenium include Brazil nuts, seafood, organ meats, and grains. However, the selenium content in food can vary based on soil levels.

Foods High in Selenium to Monitor

While generally safe, moderate consumption of very high-selenium foods is advised, especially if using supplements.

Brazil Nuts: Can contain over 95 mcg per nut.
Seafood: Good sources include tuna, halibut, sardines, and shrimp.
Meats: Organ meats like liver, as well as beef, turkey, and chicken are good sources.
Grains: Bread and other grain products can contribute to intake.

Risk of Supplements

Supplements are the most common cause of exceeding the selenium UL. Many contain 100-400 mcg per dose. Combining these with high-selenium foods increases toxicity risk. Consult a healthcare provider before taking supplements.

The Importance of Monitoring and Medical Supervision

Excess selenium can overwhelm the body's ability to excrete it, leading to accumulation. Certain individuals may be more susceptible to adverse effects. Blood tests can assess selenium status. More information is available on the National Institutes of Health (NIH) Office of Dietary Supplements website.

Conclusion

Understanding the tolerable upper intake level of selenium is crucial for preventing toxicity. The adult UL is generally 400 mcg/day in the U.S., though lower limits exist elsewhere. High-dose supplements and foods like Brazil nuts pose the greatest risk of exceeding this limit and causing selenosis. Always consult a healthcare provider regarding supplement use.

Frequently Asked Questions

A distinctive garlic-like odor on the breath is one of the earliest and most common symptoms of selenosis (selenium toxicity), often accompanied by hair and nail changes.

It is very rare to experience selenium toxicity from food alone, unless consuming extremely high quantities of high-selenium foods like Brazil nuts on a regular basis.

No, the upper limit for selenium varies depending on the region. For example, the U.S. adult UL is 400 mcg, while the European Food Safety Authority (EFSA) sets it at 255 mcg.

Yes, Brazil nuts are an exceptionally rich source of selenium. However, they should be consumed in moderation, as just a few can cause you to exceed the daily Recommended Dietary Allowance (RDA).

The Recommended Dietary Allowance (RDA) for selenium is 55 micrograms (mcg) per day for most adults.

While severe acute toxicity is rare, an accidental overdose can cause gastrointestinal issues, nausea, and vomiting. For ongoing, mild over-consumption, symptoms of selenosis may develop over time.

The Recommended Dietary Allowance (RDA) is the intake level that is considered sufficient for most people to meet their nutritional needs. The Tolerable Upper Intake Level (UL) is the maximum daily intake unlikely to cause adverse health effects.