Natural variation of selenium in Brazil nuts and soils from the Amazon region

Abstract

Brazil nut tree (Bertholletia excelsa) is native of the Amazon rainforest. Brazil nuts are consumed worldwide and are known as the richest food source of selenium (Se). Yet, the reasoning for such Se contents is not well stablished. We evaluated the variation in Se concentration of Brazil nuts from Brazilian Amazon basin, as well as soil properties, including total Se concentration, of the soils sampled directly underneath the trees crown, aiming to investigate which soil properties influence Se accumulation in the nuts. The median Se concentration in Brazil nuts varied from 2.07 mg kg (in Mato Grosso state) to 68.15 mg kg (in Amazonas state). Therefore, depending on its origin, a single Brazil nut could provide from 11% (in the Mato Grosso state) up to 288% (in the Amazonas state) of the daily Se requirement for an adult man (70 μg). The total Se concentration in the soil also varied considerably, ranging from <65.76 to 625.91 μg kg, with highest Se concentrations being observed in soil samples from the state of Amazonas. Se accumulation in Brazil nuts generally increased in soils with higher total Se content, but decreased under acidic conditions in the soil. This indicates that, besides total soil Se concentration, soil acidity plays a major role in Se uptake by Brazil nut trees, possibly due to the importance of this soil property to Se retention in the soil.

Selenium in Cardiac Surgery

“…An example of an Se‐rich food is Brazil nuts . However, even this presumably Se‐rich food differs drastically in its actual Se content, depending on the exact origin of production and the characteristics of the soil . Nevertheless, supplying patients with Se‐rich food items presurgery or post‐surgery is not feasible and can hardly be controlled for obvious reasons.…”

Natural variation of arsenic fractions in soils of the Brazilian Amazon

“…Samples were collected between 2014 and 2017. The chosen target sites for this study were the same ones used by Silva Junior et al (2017) in their survey assessing the natural variation of selenium in Brazil nuts and soils from the Amazon region, to which we have added four additional areas. Sampling sites and detailed geographic information are provided in Fig.…”

“…These samples were collected at four points and mixed to compose a single sample for each depth. The sampling method is represented schematically according to Silva Junior et al (2017).…”

“…Increased As levels have been observed in soils worldwide and also in Brazil, especially due to mining activities (Bundschuh et al, 2012). Hypothetically, we could expect high concentrations of As in soils nearby the Amazon basin because of the sediments coming through the Amazon river (and its tributaries) from the Andes, which are expected to be naturally enriched in selected volatile trace elements (e.g., Se and Hg) (Fadini and Jardim, 2001;Silva Junior et al, 2017). However, there is a lack of comprehensive information about background levels of As in soils from the Amazon basin to prove this assumption since the more recent studies have focused only in specific states of Eastern Amazon (Fernandes et al, 2018).…”

Symbiotic interaction in forage crop cultivations: A review

“…Brazil is an extensive forest plants producer due to the edaphoclimatic conditions though; most part of the soils which constitutes Brazil's territorial extension has features as low fertility mainly in primary nutrients, they are, Nitrogen (N), Phosphorus (P) and Potassium (K). These soils are highly degraded, rich in iron oxide and aluminum on the clay fraction, becoming primordial fertilizer usage in order to increase forage production and maintain availability of the pasture in a sustainable manner (Abreu et al, 2011;Rezende et al, 2017;Silva Junior et al, 2017;.…”