Seed from the tree of the same name originating in South America.High caloric food, very rich in fats, with a high percentage of unsaturated fats, proteins and fibre. It is one of the foods with the highest concentrations of selenium; one to two nuts contain the recommended daily intake for selenium (Thomson CD 2008). Its regular consumption makes it exceed the recommended daily dose (Martens IB 2015), causing excessive levels of this element in plasma (Huguenin GV 2015) and in hair between 3 and 16 times greater than normal (Momčilović B 2016). Its lipid-lowering properties are highly contentious, as while some authors have found cholesterol reducing properties (Carvalho RF 2015), others have not (Huguenin GV 2015). There are very few reports on the excess of radioactive elements accumulated in these seeds (Garay JJ 1969, Frindik O 1989, Bull RK 2006). Since the last update we have not found published data on its excretion in breast milk. Since there is doubt about whether excessive consumption of selenium increases the amount of selenium in breast milk, only occasional or very moderate consumption of Brazil nuts during breastfeeding would be prudent.