Can you get too much selenium from nuts?

November 2, 2025 •

4 min read

While most nuts contain little selenium, a single Brazil nut can provide more than your entire daily requirement, sometimes delivering up to 96 mcg. This raises a critical question: Can you get too much selenium from nuts, and what are the risks associated with this potent mineral?

Quick Summary

It is possible to get selenium toxicity, or selenosis, by consuming too many Brazil nuts due to their extremely high selenium content. Safe daily limits can be easily exceeded with only a handful of these nuts, leading to symptoms like hair loss and fatigue.

Key Points

Brazil Nuts are the Main Concern: Brazil nuts are unique among nuts for their extremely high, and variable, selenium content, posing the primary risk for dietary selenium toxicity.
Moderation is Key: To prevent selenosis, limit your intake of Brazil nuts to one or two per day, and do so occasionally rather than every day.
Know the Daily Limit: The Tolerable Upper Intake Level (UL) for adults is 400 mcg of selenium per day from all sources, a threshold that can be easily surpassed with Brazil nuts.
Watch for Symptoms: Early signs of excess selenium, or selenosis, include garlic breath, a metallic taste, fatigue, and hair loss.
Other Nuts are Safe: Most other nuts, such as almonds and walnuts, contain insignificant amounts of selenium and are not a source of toxicity risk.
Balance Your Diet: Be mindful of your overall selenium intake from all sources, including supplements, seafood, and meat, especially if you eat Brazil nuts regularly.

The Exceptionally High Selenium Content of Brazil Nuts

While nuts are a staple of a healthy diet, not all are created equal regarding their mineral content. Most common nuts, such as almonds and walnuts, contain only trace amounts of selenium, and consuming large quantities poses no risk of toxicity. However, Brazil nuts stand out as a unique and potent natural source. A single Brazil nut can contain between 68 and 91 micrograms (mcg) of selenium, an amount that can easily exceed the adult Recommended Dietary Allowance (RDA) of 55 mcg. The exact selenium level in Brazil nuts is highly variable and depends on the soil composition where the tree grew. For individuals unaware of this fact, regularly snacking on more than one or two Brazil nuts per day can lead to a dangerously high intake.

Daily Selenium Limits and the Risk of Toxicity

To prevent adverse health effects, health organizations establish a Tolerable Upper Intake Level (UL) for nutrients. For adults, the UL for selenium is set at 400 mcg per day. Exceeding this limit over a prolonged period can result in selenosis, the clinical term for selenium toxicity. Given that a handful of Brazil nuts could contain 400 mcg or more, it is surprisingly easy to reach or surpass the UL just from this single food source. Unlike other nutrients, the margin between a beneficial intake and a toxic one for selenium is relatively narrow, making mindful consumption of Brazil nuts essential.

Recognizing the Symptoms of Selenosis

Early signs of too much selenium can be subtle and easily overlooked. The most common initial indicators include a metallic taste in the mouth and a distinct garlic-like odor on the breath. As excess intake continues, more noticeable symptoms develop, affecting various body systems. For example, severe selenosis can cause hair loss and changes to the nails, such as brittleness or discoloration. Gastrointestinal issues like nausea, diarrhea, and abdominal pain are also frequently reported. In extreme, albeit rare, cases, acute selenium poisoning can lead to severe gastrointestinal and neurological problems, and even cardiac or kidney failure.

Symptoms of selenosis may include:

Metallic taste in the mouth and garlic breath
Hair loss and brittle nails
Nausea, diarrhea, and fatigue
Skin rashes or lesions
Irritability and nervous system abnormalities
Muscle tenderness and tremors

Nuts vs. Other Selenium Sources

To put the risk into perspective, it's helpful to compare the selenium content of Brazil nuts with that of other common nuts and selenium-rich foods. This highlights why Brazil nuts require special caution while other nuts do not.


Food Source	Typical Selenium Content	Risk of Toxicity from Food Alone
Brazil Nuts	~68–91 mcg per nut	High; easy to exceed daily limits
Almonds	<1 mcg per ounce	Very low; requires huge quantities
Walnuts	<1 mcg per ounce	Very low; requires huge quantities
Yellowfin Tuna	~92 mcg per 3 ounces	Possible with regular, large servings
Eggs	~30 mcg per egg	Very low; requires many eggs
Sunflower Seeds	~23 mcg per ounce	Low; moderate consumption is safe

Other Sources of Selenium to Consider

It is important to remember that nuts are not the only dietary source of selenium. A balanced intake involves considering all sources, particularly if you are a regular consumer of Brazil nuts. Integrating a variety of selenium-rich foods into your diet helps ensure you meet your nutritional needs without overdoing it on one specific item. Some of the best alternative sources include seafood and meat, which generally contain more predictable levels of selenium than plant-based foods.

High-selenium foods beyond nuts include:

Seafood, such as yellowfin tuna, halibut, sardines, and oysters
Meat, including beef, chicken, and turkey
Eggs and dairy products
Certain breads, cereals, and grains

Safe Consumption of Brazil Nuts

Moderation is the key to reaping the benefits of Brazil nuts while avoiding the risks of selenosis. For most adults, health experts recommend limiting intake to just one or two nuts per day, and consuming them only occasionally rather than daily. If you take selenium supplements, it is crucial to monitor your intake from all sources to ensure you do not exceed the 400 mcg UL. The varying selenium content of Brazil nuts, influenced by soil conditions, adds an element of uncertainty, reinforcing the need for caution. For more information on dietary minerals, consult authoritative resources like the Office of Dietary Supplements.

Conclusion

While all nuts are nutritious, the potent selenium content of Brazil nuts makes them a special case. Yes, you can get too much selenium from nuts, but only if they are Brazil nuts consumed in excess. Regular consumption of more than a couple of Brazil nuts can easily push daily selenium intake beyond safe levels, leading to selenosis. By understanding the symptoms and practicing moderation, you can enjoy the health benefits of this powerhouse nut without putting your well-being at risk. For all other nuts, enjoying them in larger quantities is not a concern for selenium toxicity.

Frequently Asked Questions

Only Brazil nuts contain high concentrations of selenium. Most other nuts, including almonds, walnuts, and pecans, have a negligible amount of this mineral.

Most health experts recommend consuming no more than one or two Brazil nuts per day to avoid exceeding safe selenium intake levels.

Excessive consumption of Brazil nuts can lead to selenium toxicity, known as selenosis, which can cause symptoms like hair loss, brittle nails, fatigue, skin rashes, and gastrointestinal issues.

Early symptoms of selenium toxicity often include a metallic taste in the mouth and breath that smells like garlic.

The Tolerable Upper Intake Level (UL) for selenium in adults is 400 micrograms (mcg) per day, a threshold that includes intake from all sources: food, beverages, and supplements.

Yes, children can also get too much selenium from Brazil nuts, and their daily upper intake limits are lower than adults. Parents should be cautious and limit their children's consumption.

Good sources of selenium include seafood (tuna, halibut), meats, eggs, and certain grains. Including a variety of these foods helps maintain healthy selenium levels without relying solely on Brazil nuts.

The selenium content of Brazil nuts varies widely depending on the soil composition where they were grown. There is no easy way to know the exact amount without laboratory testing, so it is safest to assume they are a potent source and limit your intake.