Selenium rich food - Selenium in Brazil nuts highly bioavailable

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Brazil nuts are rich sources of selenium (Se) and one ounce contains ten times the recommended dietary allowances.

Brazil nuts tree (Bertholletia excelsa) is a native of South America found in the rain forests of Brazil, Bolivia, Colombia, Guiana, Peru and Venezuela.
Though these trees are being raised as plantations their economic viability is questionable.
Apart from the food value, the fruits of this tree are good sources of vitamins like thiamine and vitamin E and minerals like calcium, magnesium, phosphorus, copper and manganese.

Selenium sources

One ounce of these fruits are found to contain as much as 550 mcg of Se which is ten times the U.S.Recommended Dietary Allowances (USRDA).
Among the nuts, these contain the rich amount of this mineral in them (2500 times more).
However the amount may vary among the regions and batches of produce.
In human body selenoproteins are required for making antioxidant enzymes and this makes selenium an essential mineral.
The high content of this mineral and vitamin E in these fruits contributes to their excellent antioxidant activity.

Food bio-availability of selenium is high in Brazil nuts

A study on comparative bio-availability was conducted by Christine D Thomson, Alexandra Chisholm, Sarah K McLachlan and Jennifer M Campbell from the Department of Human Nutrition, University of Otago, Dunedin, New Zealand.
59 adults were divided into 3 groups and fed in food 2 fruits, 100 µg this mineral as selenomethionine or placebo daily for 12 weeks.
After 12 weeks the blood levels of selenium and glutathione peroxidase (GPx) were measured and the levels were found to be significantly higher in 'eating group' than in placebo and selenomethionine groups.
It was conclusively proved that intake of this mineral and its bio-availability were far higher from these fruits than taking selenomethionine supplements.

Tips for getting most out the selenium in Brazil nuts

Rich in fats and polyunsaturated fatty acids, they tend to get rancid quickly.
Unshelled and fresh fruits are preferred as their kernel tastes better and contain up to 100 mcg of Se per fruit.
It is advised to keep them under refrigeration, so as to avoid rancidity and loss of their nutritive value.
Freezing the fruits helps in cracking them open and the kernel comes out easily.
In some rare cases some people develop allergy to these fruits.
Excess consumption must be avoided as this may lead to overdose and selenosis.

Why selenium is rich in Brazil nuts among foods?

There are many assumptions and the probable reasons may be these.
Proteins food contained in these fruits are rich in amino acids containing sulfur, like mthionine and cysteine.
These trees have extensive root system and taking up more minerals.
These are found to absorb rich amounts of many minerals including radium.
As the availability of selenium is more with this type of root system, it is used in the tissues of Brazil nuts to replace the sulfur in sulfur containing amino acids.
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Sodium selenite - Sodium selenate.
Selenium yeast.
Selenium rich food - Brazil nuts (current topic).

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