Brazil nuts depend on big wild bees and a rodent that forgets its stash
Almost every Brazil nut sold comes from wild Amazon trees, because plantations barely produce. The flowers can be opened only by large-bodied bees that vanish when forest is disturbed, and new trees mostly sprout from seeds that agoutis bury and never dig up again.
Bertholletia excelsa is one of the Amazon's giants, reaching 50 metres with a trunk up to 2 metres across, and it can live 500 years or more, often reaching a thousand. Its straight, branchless trunk lifts a broad crown above the surrounding canopy. It is the only species in its genus, named after the French chemist Claude Louis Berthollet, and it grows scattered along the Amazon, Rio Negro, Tapajós and Orinoco.
After pollination the fruit takes 14 months to ripen into a woody capsule up to 2 kilograms, heavy enough to damage vehicles and injure people when it drops. Inside, eight to 24 wedge-shaped seeds, the nuts, are packed like orange segments, sometimes in up to three stacked tiers. A small hole at one end lets agoutis gnaw in; they eat some seeds and bury the rest in caches. Seedlings may then wait dormant for years until a falling tree lets in the light.
Because the harvest is wild, the trade has been promoted as a way to earn money from rainforest without felling it. Gatherers are often migrant workers called castañeros or castanheiros. But studies of tree ages show that heavy collecting removes too many seeds: lightly harvested sites had plenty of young trees, intensely harvested ones had almost none. Logging is prohibited in Brazil, Bolivia and Peru, though illegal felling continues. World output in 2024 was 79,736 tonnes, 87 percent from Brazil and Bolivia combined.
The nuts are extraordinarily rich in selenium: a serving of six to eight averages about ten times the daily value, though batches vary widely. Their vast root systems can also concentrate naturally occurring radium where it exists in the soil, giving higher radioactivity than common foods, though still a small dose. Once on the ground they can pick up fungal aflatoxins; sorting and drying removes about 98 percent, and an EU import ban from 2003 was later lifted.
Source: Brazil nut
