Brazil nuts are very nutritious. They contain a good amount of protein and healthy fats and are quite rich in essential minerals, including calcium, magnesium, phosphorus, and zinc. They also contain plenty of vitamin E. A one-ounce serving of Brazil nuts (6 to 8 kernels) provides more than half of the copper you need in a day. You could argue that Brazil nuts are too high in minerals. One mineral, selenium, makes Brazil nuts a bit of a problem. It is because of their high selenium content that we are advised to not eat more than 2 to 4 Brazil nuts a day.
One Brazil nut can contain up to 96 micrograms (mcg) of selenium (average is 68 to 91 mcg). That is 175% of the reference daily intake or RDI, which is 55 mcg per day. It is easy to get confused about the difference between the RDI and the UTI, however.
The RDI, or recommended daily intake, is the recommended amount of a nutrient that is likely to meet the nutritional requirements of a healthy person. The RDI of particular nutrients will differ depending on age groups and gender. UTI stands for “upper tolerable intake.” This is the maximum amount of a nutrient or other chemical that a healthy individual can consume daily without risking adverse health consequences or toxicity.
Selenium is a necessary trace element for human health. The mineral is involved in DNA production, reproduction, thyroid function, immune functions, and antioxidant roles.
The upper tolerable intake (UTI) of selenium is 400 mcg per day. And, selenium can build up in your body, meaning that multiple small doses in a short period can lead to toxic levels of the mineral in your body. An intake of 750 to 850 mcg can produce functional signs of toxicity, and over 900 mcg is considered a toxic dose. This means that 9 Brazil nuts may be enough to cause symptoms of toxicity, and over 9 could be acutely toxic!
If you consume close to the RDI of selenium every day, your body can usually safely dispose of the excess. But if you consume larger amounts chronically, daily for a long enough period of time, the levels of selenium in your body can build up to toxic levels. This is why you should not eat more than 2 to 4 Brazil nuts a day. Snacking on brazil nuts freely like you would almonds, is not safe at all.
The earliest signs of selenium toxicity are garlicky breath and a metallic taste in the mouth. After chronic high intakes of selenium, “selenosis” occurs, manifesting in hair loss, brittle nails (and potentially loss of nails). Other symptoms are skin rash, nausea, diarrhea, fatigue, irritability, and nervous system abnormalities.
Acute toxicity from selenium can be life-threatening. Symptoms include neurological symptoms, respiratory distress, myocardial infarction, tremors, lightheadedness, facial flushing, kidney failure, cardiac failure, and, rarely, death. In 2008 201 people experienced severe adverse reactions from taking a liquid dietary supplement containing 200 times the labeled amount of selenium.
Should You Eat Brazil Nuts To Get Selenium?
Although you can get too much selenium from over-eating Brazil nuts, some sources claim that you should eat two or three Brazil nuts a day to ensure you have adequate selenium. While Brazil nuts are a rich source of micro-nutrients and healthy fats, you are not likely in any danger of not getting enough selenium from your diet. You certainly do not need to eat Brazil nuts to make sure you have enough of this nutrient as your body only needs trace amounts of it and selenium is found in many different foods, including animal and plant sources.
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