Which Nut Has the Highest Selenium? The Brazilian Powerhouse

December 1, 2025 •

3 min read

According to the USDA, a single Brazil nut can contain as much as 68 to 96 micrograms (mcg) of selenium, easily exceeding the daily recommended intake for adults. When considering which nut has the highest selenium, the Brazil nut is the unequivocal answer, standing far above all other nuts and many other foods.

Quick Summary

Brazil nuts are the richest food source of selenium, a vital trace mineral important for thyroid function, immunity, and overall health. However, their high potency requires mindful consumption to prevent toxicity. This guide explores the benefits, provides a comparison of selenium sources, and offers practical advice.

Key Points

Brazil nuts reign supreme: Brazil nuts have the highest selenium content of any nut, with a single nut potentially exceeding your daily recommended intake.
Selenium benefits: The mineral is essential for thyroid hormone production, a healthy immune system, and acting as a powerful antioxidant.
Consider other sources: While Brazil nuts are the most concentrated nut source, other good food sources include tuna, sardines, chicken, and eggs.
Avoid toxicity: Due to the high potency, consuming more than a few Brazil nuts daily can lead to selenosis, or selenium toxicity, with potential side effects including hair loss and brittle nails.
Soil variability: The selenium levels in Brazil nuts can vary significantly based on the soil where they are grown, so moderation is key even when consuming small amounts.

The Undisputed King of Selenium: The Brazil Nut

Brazil nuts (Bertholletia excelsa) are the edible seeds of a tree native to the Amazon rainforest and are renowned as the single greatest food source of selenium on the planet. While many foods contain selenium, the concentration found in Brazil nuts is exceptionally high. Just a single nut can provide between 68 and 96 mcg, which is well over the recommended dietary allowance (RDA) of 55 mcg for an adult.

Why Do Brazil Nuts Contain So Much Selenium?

The selenium content in Brazil nuts is not uniform and can vary dramatically depending on the soil composition where the tree was grown. The unique soil conditions in certain parts of the Amazon are rich in this trace mineral, leading to the nuts’ potent concentration. This variability means that some batches of Brazil nuts may have even higher levels than the average, which is an important consideration for consumers.

The Critical Role of Selenium in the Body

Selenium is a trace mineral, meaning the body only needs it in small amounts. However, its importance cannot be overstated. It plays a crucial role in many physiological processes.

Thyroid Function: Selenium is vital for the proper functioning of the thyroid gland, which contains the highest concentration of selenium in the body. It helps produce and convert thyroid hormones, and deficiency is linked to conditions like Hashimoto's thyroiditis.
Antioxidant Defense: As a potent antioxidant, selenium protects cells from oxidative damage caused by free radicals. This protective effect is achieved by increasing levels of the enzyme glutathione peroxidase (GPx), which helps reduce inflammation and cellular stress.
Immune System Support: Selenium is essential for a healthy immune system, playing a role in how immune cells function and defend against infections. Adequate selenium levels are associated with enhanced immune responses.
Reproductive Health: This mineral is important for male fertility, as it is involved in sperm motility. In women, it is important for a healthy pregnancy and may protect against complications like pre-eclampsia.
Brain Health: Research has linked low selenium levels to cognitive decline and neurodegenerative diseases like Alzheimer's and Parkinson's. The antioxidant properties of selenium help protect the brain from damage.

Selenium Content Comparison: Nuts and Other Foods

For context, here is how Brazil nuts compare to other popular nuts and food sources when it comes to selenium content. Keep in mind that the exact values can vary based on factors like soil quality and processing.


Food Source	Serving Size	Approximate Selenium Content	Notes
Brazil Nuts	1 nut	68-96 mcg	Extremely potent; requires moderation
Yellowfin Tuna	3 oz (cooked)	92 mcg	Excellent seafood source
Sardines (canned)	3 oz	45 mcg	Good fish source
Ham (roasted)	3 oz	24 mcg	Moderate meat source
Chicken (white meat)	3 oz	22 mcg	Lean protein source
Hard-Boiled Egg	1 large egg	15 mcg	Common dietary source
Cashews	1 oz	1 mcg	Minimal nut source compared to Brazil nuts
Pistachios	1 oz	3 mcg	Lower source, but rich in other nutrients

The Risks of Excessive Selenium Intake

While Brazil nuts are a fantastic source of selenium, consuming too many can lead to a condition known as selenosis, or selenium toxicity. The Tolerable Upper Intake Level (UL) for adults is set at 400 mcg per day. Since a single Brazil nut can contain a significant portion of this, it is easy to overdo it.

Common symptoms of selenosis include:

Hair loss
Brittle nails and nail discoloration
Gastrointestinal problems (nausea, diarrhea)
Fatigue and irritability
Garlicky breath
Skin rashes
Damage to the nervous system

For most people, a safe intake strategy involves consuming just one to three Brazil nuts per day to meet their selenium needs without risking toxicity. Those who also take multivitamin supplements containing selenium should be especially cautious and monitor their total intake. Consulting with a healthcare professional can help determine the right approach.

Conclusion: Mindful Consumption for Maximum Benefit

In the realm of nuts, Brazil nuts are the clear winner for selenium content. They offer a potent dose of this essential mineral, providing powerful benefits for thyroid health, immune function, and antioxidant defense. However, their exceptional richness also comes with a notable risk: overconsumption can lead to toxicity. The key is moderation. By sticking to just a few nuts per day and being aware of other selenium sources in your diet, you can enjoy all the nutritional advantages that the Brazilian powerhouse has to offer safely.

For more detailed information on selenium's health roles and intake recommendations, you can visit the NIH Office of Dietary Supplements website.

Frequently Asked Questions

To get the benefits of selenium without risking toxicity, most experts recommend eating no more than one to three Brazil nuts per day.

Symptoms of too much selenium can include hair loss, brittle nails, nausea, diarrhea, skin rashes, fatigue, and nerve damage.

While Brazil nuts are in a class of their own, some other nuts like pistachios and cashews contain small amounts of selenium, but nowhere near the concentration found in Brazil nuts.

Excellent sources of selenium apart from nuts include seafood like tuna and sardines, lean meats such as chicken and turkey, and eggs.

The thyroid gland requires selenium for the proper production and conversion of thyroid hormones. Selenium also protects the thyroid from oxidative stress.

Yes, the amount of selenium in Brazil nuts can vary significantly depending on the soil composition of the region where they were grown. This variability is why cautious consumption is advised.

Individuals who take selenium supplements, have thyroid issues, or live in regions with high selenium soil should be especially mindful of their intake to avoid excessive amounts.