Brazil Nut (Bertholletia excelsa) Seed Oil

Heritage and History

Brazil nut (also spelled Brazilnut) oil is pressed from the seeds of Bertholletia excelsa, known in Brazil as the castanheira. One of the giants of the Amazon rainforest, the tree can reach about 50 meters in height and live for centuries [1], rising above the surrounding forest canopy. It grows wild in Brazil, Bolivia and Peru [1, 2].

Brazil nuts have been a food staple for Indigenous and riverside communities for generations, and the oil has long been applied to treat skin irritations and dry skin and to promote healthy hair. Today the Brazil nut is one of the most important non-timber forest products of the Amazon, providing income to Indigenous, riverside and extractivist communities without the need to clear forest. The tree is legally protected in Brazil [1] and is widely seen as a symbol of the forest's abundance.

Today, Brazil Nut oil is valued in skin and hair care for its light, comfortable feel and its balanced fatty acid profile.

Cultivation and Regional Origins

Brazil nut trees depend on healthy, intact forest. Their flowers are pollinated almost exclusively by large native bees [1, 2], and their seeds are spread by agoutis, which bury them for later and forget some, allowing new trees to grow [1, 2]. Because of this, plantation-grown trees produce few nuts, and nearly all Brazil nuts are gathered from the wild [2].

The fruits are heavy, woody capsules known as ouriços that fall to the forest floor when ripe. Harvesters collect them during the rainy season [2] and crack them open to remove the seeds, which are then pressed for oil. Because the trade depends on standing forest, it gives local communities an economic reason to protect it. The species is listed as Vulnerable [1], so responsible harvesting that leaves enough seeds for regeneration matters.

Chemistry of Brazil Nut Seed Oil

Brazil nut oil is a pale yellow oil with a mild, slightly sweet, nutty scent. It stays liquid at room temperature and spreads easily, with a light, comfortable feel. Its two main fatty acids, oleic and linoleic acid, are present in roughly equal amounts. Here are the key components of pure, unadulterated Brazil Nut oil:

Oleic acid (C18:1, typically 31–41%): A monounsaturated fatty acid that gives the oil its smooth, nourishing slip. It is one of the most widely used skin-conditioning emollients in cosmetics [3].

Linoleic acid (C18:2, typically 32–42%): An essential omega-6 fatty acid that the body cannot make on its own. The skin uses it to build ceramides, the lipids that hold the outer layer of the skin together [4].

Palmitic and stearic acids (C16:0, typically 12–16%, and C18:0, typically 9–13%): Saturated fatty acids that give the oil its richness and help keep it stable.

Plant Sterols: Brazil nut oil contains plant sterols, mainly β-sitosterol, which makes up about three-quarters of the sterol fraction, along with smaller amounts of stigmasterol [5].

Vitamin E (Tocopherols): Brazil Nut oil contains vitamin E [5], a potent antioxidant that helps protect the skin from free radical damage caused by pollution. Vitamin E also supports the skin's natural healing processes, promoting a smoother, more even complexion and reducing the appearance of fine lines, wrinkles and age spots.

Phospholipids: The oil also contains phospholipids such as phosphatidylcholine [5].

Fatty acid percentages are typical specification ranges for commercial Brazil Nut seed oil; exact values vary from batch to batch.

Benefits for Skin and Hair

Brazil nut oil's balanced blend of oleic and linoleic acids makes it a nourishing everyday oil for skin and hair:

For Skin:

Nourishing Moisture: Brazil nut oil helps skin hold on to moisture, leaving it soft, smooth and comfortable. It suits dry, mature and normal skin alike.

Supports the Skin's Moisture Barrier: Rich in linoleic acid, it helps support the skin's natural moisture barrier, so skin feels less tight and dry.

Supple, Healthy-Looking Skin: With regular use, well-moisturized skin looks smoother, more supple and more radiant.

Skin Repair: Brazil Nut oil's vitamin E and fatty acids help to repair damaged skin from environmental stressors. The oil supports the skin's natural regeneration processes, helping to improve the texture and appearance of scars or stretch marks.

For Hair:

Softness and Shine: Brazil nut oil helps hair feel softer and look shinier, and helps smooth the look of dry, frizzy ends.

Scalp Comfort: Massaged into the scalp, it helps relieve the feeling of dryness and tightness.

How It Works

Most of the published science on Brazil nut comes from laboratory, animal or composition studies rather than studies on people's skin. Here is what that research found, and what it does and doesn't tell us.

Linoleic Acid and the Skin Barrier: Linoleic acid is the most abundant polyunsaturated fatty acid in the skin, and the skin builds it into specialized ceramides that help form the barrier in its outer layer [4]. In lab-grown human skin models, adding linoleic acid changed the makeup of the skin's lipids and its barrier properties [6]. These studies tested linoleic acid itself rather than Brazil nut oil, but they explain why oils rich in linoleic acid are valued in barrier-focused skin care.

Minor Components: Detailed analysis of Brazil nut oil has identified its tocopherols, plant sterols and phospholipids [5]. Research on Brazil nut oil has so far focused mainly on its composition, and few studies have tested the oil itself on human skin.

Allergen Information

Food allergens: Brazil nut is a tree nut. Tree nuts are one of the nine major food allergens recognized by the U.S. Food and Drug Administration, and Brazil nut is on the FDA’s list of tree nuts [7].

Fragrance allergens: Brazil nut seed oil is a fixed plant oil, not an essential oil, and does not appear on the European Union’s list of fragrance allergens that must be named on cosmetic labels [8].

Reported reactions: Allergic reactions to nuts are caused by their proteins. Refining removes almost all protein from plant oils, but unrefined oils can retain traces; in studies, some people with peanut allergy reacted to unrefined peanut oil but not to refined oil [9]. If you are allergic to Brazil nuts or other tree nuts, do not use unrefined Brazil nut oil without first asking your doctor.

Patch test: As with any new skincare product, try a small amount on your inner arm and wait 24 hours before wider use. If you have a known allergy, ask your doctor before using a new product.

Conclusion

Brazil Nut seed oil comes from one of the Amazon's most iconic trees and is gathered from the wild in a way that helps keep the forest standing. Its balanced blend of oleic and linoleic acids makes it a nourishing, comfortable oil that leaves skin soft and supple and helps hair look smooth and shiny.

References

[1] Carvalho, P. E. R. (2014). Castanha-da-Amazônia: Bertholletia excelsa. In P. E. R. Carvalho, Espécies arbóreas brasileiras (Vol. 5, pp. 205–214). Embrapa Informação Tecnológica; Embrapa Florestas. https://www.alice.cnptia.embrapa.br/alice/handle/doc/1140475

[2] Mori, S. A. (1992). The Brazil nut industry—past, present, and future. In M. Plotkin & L. Famolare (Eds.), Sustainable harvest and marketing of rain forest products. Island Press. https://www.nybg.org/bsci/braznut/BrazilNut.html

[3] Zhang, W.-R., Zhang, Q.-R., Zhou, Z.-Y., Zhang, Y.-F., Li, X.-W., Shen, H.-Y., Tang, L.-F., & Xiang, Q. (2025). Oxidative-inflammatory modulation of skin lipid metabolism by squalane, oleic acid, and linoleic acid. Cosmetics, 12(4), 130. https://doi.org/10.3390/cosmetics12040130

[4] Wang, X., Jia, Y., & He, H. (2024). The role of linoleic acid in skin and hair health: a review. International Journal of Molecular Sciences, 26(1), 246. https://doi.org/10.3390/ijms26010246

[5] Chunhieng, T., Hafidi, A., Pioch, D., Brochier, J., & Montet, D. (2008). Detailed study of Brazil nut (Bertholletia excelsa) oil micro-compounds: phospholipids, tocopherols and sterols. Journal of the Brazilian Chemical Society, 19(7), 1374–1380.

[6] Simard, M., Tremblay, A., Morin, S., Martin, C., Julien, P., Fradette, J., Flamand, N., & Pouliot, R. (2022). α-Linolenic acid and linoleic acid modulate the lipidome and the skin barrier of a tissue-engineered skin model. Acta Biomaterialia, 140, 261–274.

[7] U.S. Food and Drug Administration. (2025). Frequently asked questions: Food allergen labeling guidance for industry. Retrieved October 15, 2026, from https://www.fda.gov/food/food-allergensgluten-free-guidance-documents-regulatory-information/frequently-asked-questions-food-allergen-labeling-guidance-industry

[8] European Parliament & Council of the European Union. (2009). Regulation (EC) No 1223/2009 on cosmetic products, Annex III, as amended by Commission Regulation (EU) 2023/1545 on the labelling of fragrance allergens. Official Journal of the European Union. https://eur-lex.europa.eu/eli/reg/2023/1545/oj

[9] Crevel, R. W., Kerkhoff, M. A., & Koning, M. M. (2000). Allergenicity of refined vegetable oils. Food and Chemical Toxicology, 38(4), 385–393. https://doi.org/10.1016/S0278-6915(99)00158-1