Brazil Nuts and Selenium

18th Dec 2021

Brazil Nuts and Selenium

We already covered Brazil nuts benefits in a different blog post. We know that these nuts are a terrific source of selenium, an essential mineral and key nutrient that contributes to nearly every system in your body to help maintain and restore health. From mental health to heart health, immune health to thyroid function, and in between, Selenium in humans is a requirement. Unlike many other nutrients, Selenium isn’t effective as a vitamin, it must be part of your diet and intake to function and help your body.

According to the National Institutes of Health:

Selenium is a nutrient that the body needs to stay healthy. Selenium is important for reproduction, thyroid gland function, DNA production, and protecting the body from damage caused by free radicals and from infection.

Specific Health Benefits of Selenium

While research into the full nutritional benefits of selenium is always underway, some of the general topics that have shown great promise and outcomes, either by causation or correlation, include positive effects on the following:

  • Cellular health -- as an antioxidant
    Antioxidants protect and clear the body of excess free radicals and they are important to overall health. However, we tend to take in too many, and when combined with the natural ones created through our metabolism they lead to damage of the very systems they are supposed to help. Excessive free radicals come into play from smoke, alcohol, and even stress. Antioxidants serve to reduce the oxidative stress on the cells, and also reduce the free radicals to more manageable and healthy levels.

  • Risk reduction for certain cancers
    This is a reverse assumption, as those who consume too little selenium are at higher risk for specific cancers, such as colon and rectum, prostate, lung, bladder, skin, esophagus, and stomach. This could be due to other and compounding risk factors as studies into adding selenium as a supplement are still underway and results aren’t yet fully available. However, “A review of 69 studies that included over 350,000 people found that having a high blood level of selenium was associated with a lower risk of certain types of cancer, including breast, lung, colon, and prostate cancers.”

    Source: NIH

  • Protection against heart disease
    As studies have found that those with low levels of selenium in their blood have a higher risk of cardiovascular disease. Research and studies into this relationship, to determine if an increase in selenium can offer further protection, are underway.

  • Cognitive improvement
    Selenium levels in the blood naturally decline as we age, therefore the reduction in levels is part of the contributing factors to cognitive decline. While studies have offered varied results, one specific study did find demonstrable results in memory and cognitive ability in those patients who received Brazil Nuts as selenium supplements in their diets.

  • Thyroid health
    The thyroid essentially serves as the well for selenium and therefore a reduction in levels here is not only an indication of lower levels in other organs, but it also directly affects the functioning of the thyroid specifically. This is particularly applicable to women but also puts all at risk of developing thyroid disease. Additionally, those who already have thyroid disorders or thyroid hormone disorders are exponentially affected by lower levels, such as those with hormonal imbalances, metabolism issues, autoimmune thyroiditis, hypothyroidism, and Hashimoto’s disease.

  • Immunity
    Having increased selenium levels in blood directly correlates with enhanced immune systems and efficiency. As a natural antioxidant, it reduces the oxidizing stress on the body, improving the ability of the body’s natural immune system to fight off bacteria, viruses, and inflammation. It has also been shown to be effective in reducing the symptoms of HIV, while a decrease in selenium in these individuals has shown a faster progression of the disease.

  • Respiration - specifically reducing asthma symptoms
    Since selenium is an antioxidant and anti-inflammatory it can be a contributor to reducing the symptoms and severity of asthma by reducing the inflammation in the airways.

What is the Recommended Daily Intake of Selenium?

Too little selenium can be problematic for many people and can lead to the breakdown of different body functions and processes. Some of these can lead to heart disease, infertility (especially in men), arthritis, and loss of joint motion. It can be particularly dangerous to those who are suffering from digestive disorders such as Crohn’s disease, or have kidney disease, especially when requiring dialysis, or are immunocompromised such as those with HIV. Too much selenium can also have toxic effects. Therefore, the daily recommended intake of selenium from food is as follows:

(micrograms of selenium)
Birth to 6 months 45 mcg
Infants 7–12 months 60 mcg
Children 1–3 years 90 mcg
Children 4–8 years 150 mcg
Children 9–13 years 280 mcg
Teens 14–18 years 400 mcg
Adults 400 mcg
 Source: Selenium Fact Sheet for Consumers

Natural Sources of Selenium

The simplest, best dietary source for selenium is Brazil Nuts, but it’s not the only source. Selenium is found in many other foods, but its levels are wholly dependent on the quality of the soil and additives where the vegetables and grains are grown, and the animals graze on and are fed.

Some sources of Selenium include:

  • Brazil Nuts
  • Fish
  • Ham
  • Enriched foods (such as pasta, whole wheat bread, grains, and cereals)
  • Pork
  • Beef
  • Turkey
  • Chicken
  • Cottage Cheese
  • Eggs
  • Brown Rice
  • Sunflower Seeds
  • Baked beans
  • Mushrooms
  • Oatmeal
  • Spinach
  • Milk & Yogurt
  • Lentils
  • Cashews
  • Bananas

How Much Selenium is in Brazil Nuts?

That’s an excellent question. As one of the simplest and easiest ways to get Selenium, and one often used in studies using supplementation as a benchmark, Brazil Nuts are a great source. The amounts of Selenium in Brazil nuts can, however, vary greatly, depending on where they are grown. The soil and other growing conditions, including the use of fertilizers, hormones, and other chemicals can significantly change the balance in each.

In general, however, one ounce of Brazil Nuts, typically about six to eight nuts, contains about 545 micrograms of Selenium. As you can see, one ounce, then, is more than the daily recommended intake levels from ALL sources, so you want to be sure not to overindulge (they can also be filling, and fattening!).

Brazil Nuts Selenium Overdose

As we mentioned earlier, Brazil nuts are high in Selenium content, as are some other foods. And while Selenium overdose is rare, it can be very dangerous, even fatal. So it’s important to understand and be aware of what you are eating, how often, and be alert to:

  • hair loss
  • dizziness
  • nausea
  • vomiting
  • facial flushing or skin rashes
  • tremors
  • muscle soreness
  • garlic breath or metallic taste in the mouth
  • diarrhea
  • irritability
  • Brittle hair or nails
  • discolored teeth
  • nervous system problems

Extreme symptoms of selenium toxicity include:

  • Breathing
  • Tremors
  • kidney failure
  • heart attacks, and heart failure


Selenium is one of those essential nutrients that the body makes full use of throughout the different systems, making it an indispensable part of a healthy diet and protecting from diseases, reducing oxidative stress, ensuring healthy thyroid function, and reducing the risk of heart disease. The best sources of selenium are from a natural source, with the simplest food source and one with the most bang for the portion being Brazil Nuts. Studies that include Selenium supplementation frequently use Brazil Nuts as their supplement source.

Additional Resources