Brazil nut

Template:Short description Template:Use mdy dates Template:Speciesbox Brazil nut (Bertholletia excelsa) refers to a South American tree in the family Lecythidaceae as well as the tree's commercially-harvested edible seeds. It is one of the largest and longest-lived trees in the Amazon rainforest. The fruit and its nutshell – containing the edible nut – are relatively large and weigh as much as Template:Cvt in total. As food, Brazil nuts are notable for diverse content of micronutrients, especially a high amount of selenium. The wood of the Brazil nut tree is prized for its quality in carpentry, flooring, and heavy construction.

In 2023, Brazil and Bolivia combined produced 91% of the world total of Brazil nuts.

Common names

In Portuguese-speaking countries, like Brazil, they are variously called "" (meaning "cashew from Brazil" in Portuguese), "" (meaning "cashew from Pará" in Portuguese), castanha-da-amazônia, castanha-do-acre, "" (meaning "Amazonian nut" in Portuguese), noz boliviana, tocari ("probably of Carib origin"), and tururi (from Tupi turu'ri).

In various Spanish-speaking countries of South America, Brazil nuts are called , , or .

In North America, as early as 1896, Brazil nuts were sometimes known by the slang term "nigger toes", a vulgarity that fell out of use after the racial slur became more socially unacceptable.

Description

File:Brazil Nut - Project Gutenberg eBook 11662.jpg

Depiction of the Brazil nut in Scientific American Supplement, No. 598, June 18, 1887

The Brazil nut is a large tree, reaching Template:Convert tall, with a trunk Template:Cvt in diameter, making it among the largest of trees in the Amazon rainforest. It may live for 500 years or more, and can often reach a thousand years of age. The stem is straight and commonly without branches for well over half the tree's height, with a large, emergent crown of long branches above the surrounding canopy of other trees.

The bark is grayish and smooth. The leaves are dry-season deciduous, alternate, simple, entire or crenate, oblong, Template:Convert long, and Template:Cvt broad. The flowers are small, greenish-white, in panicles Template:Cvt long; each flower has a two-parted, deciduous calyx, six unequal cream-colored petals, and numerous stamens united into a broad, hood-shaped mass.

Reproduction

Brazil nut trees produce fruit almost exclusively in pristine forests, as disturbed forests lack the large-bodied bees of the genera Bombus, Centris, Epicharis, Eulaema, and Xylocopa, which are the only ones capable of pollinating the tree's flowers, with different bee genera being the primary pollinators in different areas, and different times of year. Brazil nuts have been harvested from plantations, but production is low and is currently not economically viable.

File:Brazil nut DSC05477.JPG

A freshly cut Brazil nut fruit

The fruit takes 14 months to mature after pollination of the flowers. The fruit itself is a large capsule Template:Cvt in diameter, resembling a coconut endocarp in size and weighing up to Template:Cvt. It has a hard, woody shell Template:Cvt thick, which contains eight to 24 wedge-shaped seeds Template:Cvt long (the "Brazil nuts") packed like the segments of an orange, but not limited to one whorl of segments. Up to three whorls can be stacked onto each other, with the polar ends of the segments of the middle whorl nestling into the upper and lower whorls (see illustration above).

The capsule contains a small hole at one end, which enables large rodents like the agouti to gnaw it open. They then eat some of the seeds inside while burying others for later use; some of these are able to germinate into new Brazil nut trees. Most of the seeds are "planted" by the agoutis in caches during wet season, and the young saplings may have to wait years, in a state of dormancy, for a tree to fall and sunlight to reach it, when it starts growing again.

Taxonomy

The Brazil nut family, the Lecythidaceae, is in the order Ericales, as are other well-known plants such as blueberries, cranberries, sapote, gutta-percha, tea, phlox, and persimmons. The tree is the only species in the monotypic genus Bertholletia, named after French chemist Claude Louis Berthollet.

Distribution and habitat

The Brazil nut is native to the Guianas, Venezuela, Brazil, eastern Colombia, eastern Peru, and eastern Bolivia. It occurs as scattered trees in large forests on the banks of the Amazon River, Rio Negro, Tapajós, and the Orinoco. The fruit is heavy and rigid; when the fruits fall, they pose a serious threat to vehicles and potential for traumatic brain injury of people passing under the tree.

Ecology

Capuchin monkeys have been reported to open Brazil nuts using a stone as an anvil.

Production

Brazil nut production
2023, tonnes

	35,351
	33,650
	6,909
World	75,910
Source: FAOSTAT of the United Nations

In 2023, world production of Brazil nuts (in shells) was 75,910 tonnes, most of which derive from wild harvests in tropical forests, especially the Amazon regions of Brazil and Bolivia which together produced 91% of the total (table).

Environmental effects of harvesting

Since most of the production for international trade is harvested in the wild, the business arrangement has been advanced as a model for generating income from a tropical forest without destroying it. The nuts are most often gathered by migrant workers known as castañeros (in Spanish) or castanheiros (in Portuguese). Logging is a significant threat to the sustainability of the Brazil nut-harvesting industry.

Analysis of tree ages in areas that are harvested shows that moderate and intense gathering takes so many seeds that not enough are left to replace older trees as they die. Sites with light gathering activities had many young trees, while sites with intense gathering practices had nearly none.

Toxicity

File:Brazil nuts.jpg

Brazil nuts after shell removal

Brazil nuts are susceptible to contamination by aflatoxins, produced by fungi, once they fall to the ground. Aflatoxins can cause liver damage, including possible cancer, if consumed. Aflatoxin levels have been found in Brazil nuts during inspections that were far higher than the limits set by the EU. However, mechanical sorting and drying was found to eliminate 98% of aflatoxins; a 2003 EU ban on importation was rescinded after new tolerance levels were set.

The nuts may contain traces of radium, a radioactive element, with a kilogram of nuts containing an activity between Template:Convert. This level of radium is small, although higher than in other common foods. According to Oak Ridge Associated Universities, elevated levels of radium in the soil does not directly cause the concentration of radium, but "the very extensive root system of the tree" can concentrate naturally occurring radioactive material, when present in the soil. Radium can be concentrated in nuts only if it is present in the soil.

Brazil nuts also contain barium, a metal with a chemical behavior quite similar to radium. While barium, if ingested, can have toxic effects, such as weakness, vomiting, or diarrhea, the amount present in Brazil nuts is orders of magnitude too small to have noticeable health effects.

European Union import regulation

In 2003, the European Union imposed strict regulations on the import of Brazilian-harvested Brazil nuts in their shells, as the shells are considered to contain unsafe levels of aflatoxins, a potential cause of liver cancer.

Uses

Nutrition

Brazil nuts are 3% water, 14% protein, 12% carbohydrates, and 66% fats. The fat components are 16% saturated, 24% monounsaturated, and 24% polyunsaturated.

In a Template:Convert reference amount, Brazil nuts supply 659 calories, and are a rich source (20% or more of the Daily Value, DV) of dietary fiber (30% DV), thiamin (54% DV), vitamin E (38% DV), magnesium (106% DV), phosphorus (104% DV), manganese (57% DV), and zinc (43% DV). Calcium, iron, and potassium are present in moderate amounts (10–19% DV).

Selenium

Brazil nuts are a particularly rich source of selenium, with just Template:Cvt supplying 544 micrograms of selenium or 10 times the DV of 55 micrograms. However, the amount of selenium within batches of nuts may vary considerably.

The high selenium content is used as a biomarker in studies of selenium intake and deficiency. Consumption of just one Brazil nut per day over 8 weeks was sufficient to restore selenium blood levels and increase HDL cholesterol in obese women.

Oil

File:Castanha-copl6.JPG

Brazil nut oil

Brazil nut oil contains 48% unsaturated fatty acids composed mainly of oleic and linoleic acids, the phytosterol, beta-sitosterol, and fat-soluble vitamin E.

The following table presents the composition of fatty acids in Brazil nut oil:

Palmitic acid	10%
Palmitoleic acid	0.2%
Stearic acid	6%
Oleic acid	24%
Linoleic acid	24%
Alpha-linolenic acid	0.04%
Saturated fats	16%
Unsaturated fats	48%

Wood

The lumber from Brazil nut trees (not to be confused with Brazilwood) is of excellent quality, having diverse uses from flooring to heavy construction. Logging the trees is prohibited by law in all three producing countries (Brazil, Bolivia, and Peru). Illegal extraction of timber and land clearances present continuing threats. In Brazil, cutting down a Brazil nut tree requires previous authorization from the Brazilian Institute of Environment and Renewable Natural Resources.

Other uses

Brazil nut oil is used as a lubricant in clocks and in the manufacturing of paint and cosmetics, such as soap and perfume. Because of its hardness, the Brazil nutshell is often pulverized and used as an abrasive to polish materials, such as metals and ceramics, in the same way as jeweler's rouge, while charcoal from the shells can be used to purify water.

See also

• Brazil nut cake
• List of culinary nuts
• Official list of endangered flora of Brazil
• Granular convection, also known as the "Brazil nut effect"