Selenium, Brazil Nuts & Ginger

They say that British soils lack selenium (Se), a metalloid element essential for our health. Selenium deficiency causes selenosis (damage to hair and nails), skin lesions, and neurological problems. One has to be careful, however, because selenium can be toxic to humans at high doses. So how much is enough but not too much, and how can we make up for the lack of selenium in British agricultural products?

The current WHO recommended intake is 33-34 micrograms of selenium per day for men and 25-26mcg for non-lactating women. Selenosis can manifest itself with an intake of 910mcg/day, but up to 450mcg/day is deemed ok. Jane Clarke, a nutritionist, advocates eating Brazil nuts as daily snacks to make up for this Se deficiency. Brazil nuts have 1530mcg of selenium per 100 grams (there are 140g of Brazils in an 8-oz cup); eating this many grams of Brazil nuts is clearly unwise as it exceeds the toxicity threshold. If the ok value is 450mcg (29% of the amount of selenium in 100 grams), then about 29 grams of nuts (about 1 oz) is allowable. Brazil nuts weigh 4g each on average, so a small handful (7 or so) would suffice. 

However, Brazil nuts are high in calories; an ounce (28g) is about 190 calories. So we have decided one-nut-a-day is a good policy as insurance, since selenium (110mcg) is also in our multi-vitamins. Jane Clarke mentioned raisins as a good companion to Brazil nuts, but how about a piece of crystallized ginger? Both the nuts and ginger have important medicinal properties, the latter supposedly preventing colds. Well, it didn't keep my husband from catching a zinger last weekend, but the combination of Brazil nut and ginger is a tasty treat anyway and worth eating just for its yum-factor.

Environment Agency (2009) "Soil guideline values for selenium in soil." Science Report SC050021/Selenium SGV
Kirschmann, J.D. & Nutrition Search, Inc.(2007) Nutrition Almanac. New York: McGraw Hill