Brazil nuts are tree nuts native to the Amazon rainforest in Brazil, Bolivia, and Peru. Their smooth, buttery texture and nutty flavor are typically enjoyed raw or blanched.

These nuts are energy dense, highly nutritious, and one of the most concentrated dietary sources of the mineral selenium.

Eating Brazil nuts may benefit your health in several ways, including regulating your thyroid gland, reducing inflammation, and supporting your heart, brain, and immune system.

Here are 7 proven health and nutrition benefits of Brazil nuts.

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Brazil nuts are very nutritious and energy dense.

A 1-ounce (28-gram) serving of Brazil nuts contains the following nutrients (1, 2):

  • Calories: 187
  • Protein: 4.1 grams
  • Fat: 19 grams
  • Carbs: 3.3 grams
  • Fiber: 2.1 grams
  • Selenium: 988% of the Reference Daily Intake (RDI)
  • Copper: 55% of the RDI
  • Magnesium: 33% of the
  • Phosphorus: 30% of the RDI
  • Manganese: 17% of the RDI
  • Zinc: 10.5% of the RDI
  • Thiamine: 16% of the RDI
  • Vitamin E: 11% of the RDI

Brazil nuts are rich in selenium, with just one nut containing 96 mcg, or 175% of the RDI. Most other nuts provide less than 1 mcg, on average (3).

Additionally, they have higher concentrations of magnesium, copper, and zinc than most other nuts, although the exact amounts of these nutrients can vary depending on climate and soil (3).

Finally, Brazil nuts are an excellent source of healthy fats. In fact, 36% of the fats in Brazil nuts are 37% polyunsaturated fatty acids, a type of fat that has been shown to benefit heart health (1, 4).

Summary Brazil nuts are energy dense and rich in healthy fats, selenium, magnesium, copper, phosphorus, manganese, thiamine, and vitamin E.

Brazil nuts are a rich source of selenium. In fact, they contain more of this mineral than any other nut with an average of 96 mcg per nut. However, some pack as much as 400 mcg per nut (1, 3).

The RDI for selenium is 55 mcg per day for adults. Thus, the average Brazil nut contains 175% of the required amount of this mineral (1, 2).

Selenium is a trace element that is vital for the proper functioning of your body. It is essential for your thyroid and influences your immune system and cell growth (5).

Indeed, higher levels of selenium have been linked to enhanced immune function and better outcomes for cancer, infections, infertility, pregnancy, heart disease, and mood disorders (6).

Although selenium deficiency is rare, many people around the world have insufficient selenium intake for optimal functioning. For example, suboptimal selenium status has been found in people throughout Europe, the United Kingdom, and the Middle East (7).

Brazil nuts are a highly effective way to maintain or increase your selenium intake. In fact, one study in 60 people found that eating two Brazil nuts per day was as effective as taking a selenium supplement at raising selenium levels (8).

Summary Brazil nuts are rich in selenium. One nut can contain 175% of the RDI. Selenium is an essential trace element that is vital for your immune system, thyroid gland, and cell growth.

Your thyroid is a small, butterfly-shaped gland that lies in your throat. It secretes several hormones that are essential for growth, metabolism, and body temperature regulation.

Thyroid tissue has the highest concentration of selenium, as it’s required for the production of the thyroid hormone T3, as well as proteins that protect your thyroid from damage (9, 10).

Low selenium intake can lead to cellular damage, reduced thyroid activity, and autoimmune disorders like Hashimoto’s thyroiditis and Graves' disease. It may also increase your risk of thyroid cancer (5, 9).

One large study in China showed that people with low selenium levels had a significantly higher prevalence of thyroid disease, such as hypothyroidism, thyroiditis, and an enlarged thyroid, compared to those with normal levels (11).

This highlights the importance of getting adequate selenium intake. Just one Brazil nut per day should deliver enough selenium to maintain proper thyroid function (1).

Summary Your thyroid gland produces hormones that are necessary for growth, metabolism, and body temperature regulation. One Brazil nut contains enough selenium to support the production of thyroid hormones and proteins that protect your thyroid.

As well as ensuring proper thyroid function, selenium may improve symptoms in people who have disorders of the thyroid.

Hashimoto's thyroiditis is an autoimmune disorder in which the thyroid tissue is gradually destroyed, leading to hypothyroidism and a range of symptoms like fatigue, weight gain, and feeling cold.

Several reviews have found that supplementing with selenium may improve immune function and mood in people with Hashimoto's thyroiditis (12, 13, 14).

However, two other reviews concluded that there is not enough evidence to determine selenium’s role in treating the disease. Therefore, further research is needed (15, 16).

Meanwhile, Graves’ disease is a thyroid disorder in which too much thyroid hormone is produced, leading to symptoms like weight loss, weakness, sleeping problems, and bulging eyes.

Studies have shown that supplementing with selenium may improve thyroid function and delay the progression of some symptoms in people with this disease. However, more research is needed (17).

No studies have investigated the use of Brazil nuts as a selenium source, specifically, in people with thyroiditis or Graves' disease. Nevertheless, including them in your diet may be a good way to ensure that your selenium status is adequate.

Summary Supplementing with selenium may benefit people with thyroid disorders such as Hashimoto's thyroiditis and Graves' disease. Yet, further research is needed.

Brazil nuts are rich in antioxidants, which are substances that help keep your cells healthy. They do this by combating damage caused by reactive molecules called free radicals.

Brazil nuts contain several antioxidants, including selenium, vitamin E, and phenols like gallic acid and ellagic acid (3).

Selenium increases levels of an enzyme known as glutathione peroxidase (GPx), which helps reduce inflammation and protect your body from oxidative stress — an imbalance between antioxidants and free radicals that can lead to cellular damage (18, 19, 20).

The anti-inflammatory effects of brazil nuts can be achieved from single, large doses and small doses over a longer period.

One study in 10 people noted that a single 20- or 50-gram serving (4 or 10 nuts, respectively) significantly reduced a number of inflammatory markers, including interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) (21).

Another three-month study gave people undergoing treatment for kidney failure one brazil nut per day. It found that their selenium and GPx levels had increased, while their levels of inflammatory markers and cholesterol had significantly decreased (22).

However, follow-up studies observed that once people stopped eating Brazil nuts, these measurements returned to their original levels. This demonstrates that long-term dietary changes are needed to reap the benefits of Brazil nuts (23, 24).

Summary Brazil nuts contain antioxidants like selenium, vitamin E, and phenols. Just one nut per day can lead to reduced inflammation. Nevertheless, your intake needs to be consistent to continue experiencing the benefit.

Brazil nuts contain heart-healthy fatty acids, such as polyunsaturated fats, and are rich in antioxidants, minerals, and fiber, all of which may help lower your risk of heart disease (25).

One study in 10 healthy adults investigated the effects of eating Brazil nuts on cholesterol levels. It gave them either 5, 20, or 50 grams of Brazil nuts or a placebo.

After 9 hours, the group that received a 20- or 50-gram serving had lower levels of LDL (bad) cholesterol and higher levels of HDL (good) cholesterol, compared to groups that received lower doses (26).

Another study analyzed the effects of eating Brazil nuts in obese people with selenium deficiency who were undergoing treatment for kidney disease.

It found that eating Brazil nuts containing 290 mcg of selenium daily for 8 weeks significantly increased HDL cholesterol levels. Improving your HDL cholesterol levels may decrease your risk of heart disease (19).

Furthermore, a 16-week study in obese teenagers observed that eating 15–25 grams of Brazil nuts per day improved blood vessel function and reduced LDL cholesterol and triglyceride levels (27).

Brazil nuts’ effects on heart health are promising. Nevertheless, further research is needed to determine the optimal dose and which populations might reap the greatest benefits.

Summary Eating Brazil nuts may boost your heart health by reducing LDL (bad) cholesterol, increasing HDL (good) cholesterol, and improving blood vessel function.

Brazil nuts contain ellagic acid and selenium, both of which can benefit your brain.

Ellagic acid is a type of polyphenol in Brazil nuts. It has both antioxidant and anti-inflammatory properties that may have protective and antidepressant effects on your brain (28, 29, 30).

Selenium may also play a role in brain health by acting as an antioxidant (31).

In one study, older adults with mental impairment ate one Brazil nut per day for six months. In addition to experiencing increased selenium levels, they showed improved verbal fluency and mental function (31).

Low selenium levels are associated with neurodegenerative diseases like Alzheimer's and Parkinson's, so ensuring adequate intake is important (32, 33).

What's more, some research suggests that supplementing with selenium may help mediate a poor mood, which is significantly associated with inadequate selenium intake. However, results are conflicting, and further research is needed (34, 35).

Summary Brazil nuts contain ellagic acid, which may have protective effects on your brain. Additionally, selenium may reduce your risk of some brain diseases and improve mental performance and mood. Yet, further research is needed.

Brazil nuts offer some impressive health benefits, but eating too many could be harmful.

In fact, an intake of 5,000 mcg of selenium, which is the amount in approximately 50 average-sized Brazil nuts, can lead to toxicity. This dangerous condition is known as selenosis and can cause breathing problems, heart attack, and kidney failure (36).

Furthermore, too much selenium, particularly from supplements, has been linked to an increased risk of diabetes and prostate cancer (37, 38, 39).

However, communities in the Amazon with traditional diets that are naturally high in selenium have not shown any negative effects or signs of selenium toxicity (40).

Nonetheless, it’s important to limit your daily intake of Brazil nuts.

The upper level of selenium intake for adults is 400 mcg per day. For this reason, it’s important to not eat too many Brazil nuts and check nutrition labels for selenium content.

Limiting your intake to one to three Brazil nuts per day is a smart way to avoid consuming too much selenium (25).

Additionally, those with nut allergies may be allergic to Brazil nuts and need to avoid them.

Summary Selenium toxicity is a rare but dangerous, potentially life-threatening condition. The safe upper intake level for selenium is 400 mcg. It’s important to limit your intake to 1–3 Brazil nuts per day or check how much selenium is in the nuts you buy.

Brazil nuts are nutritional powerhouses, providing healthy fats, antioxidants, vitamins, and minerals. They’re particularly high in selenium, a mineral with potent antioxidant properties.

Eating Brazil nuts may reduce inflammation, support brain function, and improve your thyroid function and heart health.

To avoid consuming too much selenium, limit your intake to one to three Brazil nuts per day.