Nutrition Myths
Too many Brazil nuts can cause selenium poisoning

SUMMARY

  • Brazil nuts contain high amounts of selenium.
  • Eating more than 4 nuts daily, may cause nausea, vomiting and diarrhea.
  • Eating high amounts of Brazil nuts for a long period of time, may lead to selenosis.
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Too many Brazil nuts can cause selenium poisoning

Brazil nuts are exceptionally high in selenium.

Selenium is a powerful antioxidant and an essential trace mineral. It is necessary for reproduction, thyroid gland function, the immune system, and DNA production. However, an excess of selenium may lead to toxicity.

The maximum safe limit observed through studies was 800mcg of selenium per day. However, for safety reasons, the official upper limit is 400mcg.

The maximum daily intake of selenium has been set for various age groups. (1)

Tolerable Upper Intake Levels of selenium for different age groups.

Age groupDaily upper limit (mcg)Amount of kernels
0 - 6 months45< 1
7 - 12 months60< 1
1-3 y901
4-8 y1501.5
9-13 y2803
14-18 y4004
19 y +4004

A long-term intake of selenium above that limit, may result in an excessive amount of selenium in the blood, which leads to selenosis.

Since Brazil nuts are a great source of selenium, too many of them may contribute to an excessive intake of this trace element.

It is assumed that one 5g Brazil nut kernel contains about 100mcg of selenium. However, the concentration of selenium in Brazil nuts, depends on the selenium level of the soils that they are grown in. 

For instance Brazil nuts are higher in selenium if grown in the selenium rich soils of the Eastern region of Amazon, in comparison to the Western part of Amazon. (2)

Considering the recommended daily intake and the upper limit of selenium, the consumption of Brazil nuts should be limited to four kernels daily.

Note: foods usually contain high doses of a specific nutrient, which in high doses may cause negative health effects. Therefore, we should always make sure that our diet is balanced and that we rotate foods on a regular basis.

Other common reasons why selenosis occurs, include overdosing on selenium supplements or if you live in an area rich in selenium and consume foods with a selenium high content. (3, 4, 5, 6, 7, 8)

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