Brazil Nuts: Cholesterol and Inflammation


Brazil nuts are best known for selenium, but a second set of claims surrounds them: that a nut or two a day lowers cholesterol, protects LDL from oxidation and calms inflammation. This page goes through every human trial in our verified set that measured blood fats or inflammatory markers after people ate Brazil nuts, a Brazil nut flour or Brazil nut oil, along with the results that went the other way. It also looks at what the nut's fat actually is, how it compares with other nuts, and which explanations for the findings are still only ideas. The short version: the trials are small, many have no control group, the selenium doses are very uneven, and the results point in more than one direction.


Table of Contents

  1. The Fat Profile, Compared With Other Nuts
  2. Selenium, Polyphenols and Sterols
  3. How Small the Trials Are
  4. Trials Measuring Cholesterol and Triglycerides
  5. The Brazil Nut Oil Result
  6. Oxidized LDL and Fat Oxidation Markers
  7. Trials Measuring Inflammation
  8. When the Nut Was Very High in Selenium
  9. Mixed-Nut Trials and the Wider Nut Evidence
  10. Selenium, Fat or Polyphenols? The Hypotheses
  11. What Is Not Known
  12. Who the Research Raises Cautions For
  13. Connections
  14. Key Research Papers
  15. Featured Videos

The Fat Profile, Compared With Other Nuts

About two thirds of a Brazil nut's weight is fat. USDA FoodData Central lists 67.1 g of fat per 100 g of dried, unblanched Brazil nuts (FDC ID 170569). That fat breaks down as:

The saturated fat figure stands out once Brazil nuts are set beside other common nuts. The table uses USDA FoodData Central values per 100 g. "Saturated share" is saturated fat divided by total fat.

Nut (USDA entry)Total fatSaturated fatSaturated share of fat
Brazil nuts, dried, unblanched67.1 g16.1 g24%
Macadamia nuts, raw75.8 g12.1 g16%
Cashew nuts, raw43.8 g7.8 g18%
Pistachio nuts, raw45.3 g5.9 g13%
Peanuts, all types, raw49.2 g6.3 g13%
Walnuts, English65.2 g6.1 g9%
Pecans72.0 g6.2 g9%
Almonds49.9 g3.8 g8%
Hazelnuts60.8 g4.5 g7%

By these USDA figures, Brazil nuts carry the most saturated fat of the nine common nuts, both by weight and as a share of their fat. Macadamias and cashews come next. Two other points from the same entries matter for cholesterol:

A Brazilian laboratory study of Amazonian oils calculated two indexes from the fatty-acid makeup of Brazil nut oil: an atherogenicity index of 0.20 and a thrombogenicity index of 0.42. Both are described as low (Pereira 2019). These indexes are arithmetic on fatty-acid percentages. They are not measurements of what happens in a person's arteries.

On fat alone, then, the Brazil nut does not look like the strongest cholesterol food among nuts. Any cholesterol effect in the trials below has to be read against that.

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Selenium, Polyphenols and Sterols

Three other groups of compounds come up when researchers try to explain Brazil nut results:

Most Brazil nut trials give such a small amount, often one nut a day (roughly 5 g), that the fat, fiber and polyphenol doses are tiny. The one nutrient that is not tiny at that dose is selenium. That is why many researchers treat these studies mainly as selenium studies.

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How Small the Trials Are

A 2022 systematic review collected 24 clinical studies of regular Brazil nut eating. Fifteen of the 24 were not randomized. In all of them the nuts were eaten as part of people's normal free-living diet (da Silva 2022). The review reported improved lipid markers in healthy people and in people with obesity, and improved lipid profiles, oxidative stress and inflammation in people on hemodialysis. It also reported conflicting results for a marker of fat oxidation in people with coronary artery disease.

Looking at the individual trials, a few features recur:

Single-meal studies, which measure blood fats in the hours or days after one serving, are sometimes quoted for Brazil nuts. A single meal cannot show what happens over months or years. No single-meal study is among the records verified for this page, so none is described here.

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Trials Measuring Cholesterol and Triglycerides

Defatted Brazil nut flour in treated high cholesterol (Rio de Janeiro)

This randomized, placebo-controlled, double-blind trial enrolled 77 people with high cholesterol and high blood pressure who were already taking cholesterol-lowering drugs. Everyone received personal dietary guidance. One group added 13 g a day of partially defatted Brazil nut flour (about 227.5 mcg of selenium); the other added dyed cassava flour as a placebo. Both were followed for 90 days.

Within the Brazil nut group, total cholesterol fell by an average of 20.5 mg/dL, non-HDL cholesterol by 19.5 mg/dL and apolipoprotein A-1 (the main protein of HDL particles) by 10.2 mg/dL. The ApoB/ApoA-1 ratio did not change. The key point is the comparison between groups: the trial found no statistical difference in serum lipids or blood pressure between the Brazil nut group and the placebo group. The placebo group's free T3, an active thyroid hormone, fell slightly, and its lipoprotein(a) rose. The authors concluded that the flour seemed to help keep T3 levels steady and contributed to lower blood fats (Carvalho 2015). Because the group-versus-group comparison was null, "within-group" changes are the weaker evidence here.

One nut a day in 130 healthy adults (São Paulo)

130 healthy volunteers ate one Brazil nut a day for 8 weeks, then stopped for 8 weeks. Total cholesterol and fasting glucose were lower after the 8 weeks of nuts. There was no separate control group. The study also genotyped people for variants in selenoprotein genes. A variant in the selenoprotein P gene (rs7579) was linked with cholesterol response, with lower levels in people carrying the GG genotype, a result the authors reported at p = 0.053, right at the usual cut-off for chance (Donadio 2018).

One nut a day in people on hemodialysis

Forty people on maintenance hemodialysis (treatment that filters the blood when the kidneys have failed) each received one Brazil nut a day for 3 months. Afterwards, HDL ("good") cholesterol had risen and LDL had fallen significantly. There was no control group; every participant got the nut (Stockler-Pinto 2014). The inflammation results from the same study are below.

One nut a day in people taking statins

Thirty-two patients taking statins, the most common cholesterol-lowering drugs, ate one Brazil nut daily for 3 months, again without a control group. The study's main finding was genetic: variants in the selenoprotein P gene influenced how triglycerides and LDL responded, along with an antioxidant enzyme and creatine kinase, a muscle enzyme (Watanabe 2022). The abstract does not report an overall cholesterol change for the group as a whole.

What these four studies add up to

One placebo-controlled trial with a null between-group result, and three before-and-after studies, two of which suggest the response depends partly on a person's genes. That is suggestive, but it is not the kind of evidence that settles whether Brazil nuts lower cholesterol.

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The Brazil Nut Oil Result

One randomized trial tested the oil on its own. Thirty-one people with metabolic syndrome took 10 mL a day of either Brazil nut oil (15 people) or soybean oil (16 people) for 30 days, with no other change in lifestyle.

The authors described the blood-fat changes in both groups as undesirable, and the drop in malondialdehyde as the one favourable effect of the Brazil nut oil (Costa e Silva 2019). This was a 30-day study in 31 people, so it cannot say what would happen over a longer period. It does show that the oil, which carries the nut's fat but little of its selenium, did not reproduce the improvements reported in some whole-nut studies. In this trial its effect on HDL and triglycerides ran the other way.

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Oxidized LDL and Fat Oxidation Markers

LDL particles become more harmful to artery walls when their fats are oxidized, so some trials measured oxidized LDL, or markers of fat oxidation in general, instead of LDL itself.

The systematic review described the evidence on fat oxidation in coronary artery disease as conflicting (da Silva 2022).

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Trials Measuring Inflammation

Inflammation is usually measured through blood proteins. C-reactive protein (CRP) is made by the liver when inflammation is active. Cytokines such as interleukin-6 (IL-6), tumour necrosis factor (TNF) and interleukin-1β are signalling proteins that immune cells use to switch inflammation on.

Hemodialysis: cytokines fell

In the 40-person hemodialysis study, TNF-α and IL-6 in plasma fell significantly after 3 months of one nut a day, while plasma selenium and glutathione peroxidase activity rose (Stockler-Pinto 2014). People on dialysis often have low selenium and high background inflammation, so they may have more room to change. With no control group, though, the study cannot rule out other causes.

Women with overweight or obesity on a calorie-reduced diet

This 8-week controlled trial was not randomized. It allocated 56 women with overweight or obesity to one of two groups, both on a diet 500 kcal a day below their needs. One group ate no nuts. The other ate 8 g of Brazil nuts a day, supplying about 347.2 mcg of selenium. Forty-six women finished. Both groups cut similar amounts of energy; average weight loss was 2.5 kg in the control group and 3.5 kg in the Brazil nut group.

At the end, the Brazil nut group had lower CRP, TNF, IL-1β and IL-8 than the control group, and lower gut permeability on a sugar-absorption test (the lactulose/mannitol ratio). A rise in blood selenium predicted a fall in IL-8. The authors wrote that the effects "seem to be Se status-dependent" (Silveira 2024). The non-random allocation and the slightly different weight loss between groups are both reasons for caution.

The mixed-nut trial

In the San Diego mixed-nut trial, which included Brazil nuts in its blend, CRP showed only a non-significant downward trend (Nora 2023).

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When the Nut Was Very High in Selenium

The trial that most complicates the anti-inflammatory story came from the same research network in São Paulo. Fifty-five women with obesity were randomly assigned to eat one Brazil nut a day or nothing, for 2 months. The nuts used were unusually rich: about 1,261 mcg of selenium per nut. That is roughly three times the 400 mcg daily upper intake level for adults set by the US Institute of Medicine (NIH Office of Dietary Supplements).

None of the women was selenium-deficient at the start. After 2 months, every selenium marker had risen in the nut group. The amount of IL-6, TNF-α, TLR2 and TLR4 in the blood (TLRs are immune receptors that detect threats) did not change. However, the gene activity behind several of these inflammatory signals increased. The control group showed no changes. The authors described this as a possible sign of a pro-inflammatory stimulus from Brazil nuts this high in selenium (Duarte 2019).

A second report from the same trial (54 women, 29 eating nuts) looked at microRNAs, small molecules that help control gene activity. Two of them, miR-454-3p and miR-584-5p, rose after Brazil nut intake (Reis 2019). What that means for cholesterol or inflammation is not yet known.

Put next to the Silveira trial (about 347 mcg a day, lower inflammatory markers) and the hemodialysis study (people who often start low), the Duarte result fits a pattern seen across selenium research. Effects may depend on how much selenium a person already has and how much they get. More is not automatically better, and in people who were already replete, a very high dose went in the unwanted direction on gene activity. Selenium excess is covered in detail on the selenium overload and safety page.

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Mixed-Nut Trials and the Wider Nut Evidence

DICA-NUTS: the largest trial to include Brazil nuts

This multicentre randomized trial in Brazil enrolled 388 adults over 40 who had had a heart attack 2 to 6 months before. Everyone followed a Brazilian cardioprotective diet. Half also received 30 g a day of mixed nuts: 10 g of peanuts, 10 g of cashews and 10 g of Brazil nuts. After 16 weeks, LDL cholesterol did not differ between the groups (difference 3.48 mg/dL, 95% confidence interval −3.45 to 10.41, p = 0.32). Other blood fats, blood-sugar measures and body measurements did not differ either (Bersch-Ferreira 2024). The analysis was adjusted for each person's statin treatment. Still, it is a null result from the largest trial in which Brazil nuts were part of the intervention.

San Diego mixed-nut trial

Twenty-nine adults with overweight or obesity ate either 42.5 g a day of mixed nuts (cashews, almonds, macadamias, Brazil nuts, pecans, pistachios, walnuts and peanuts) or calorie-matched pretzels for 16 weeks. Total cholesterol, LDL, HDL and lipoprotein(a) did not differ between the groups. The nut group had lower body fat percentage and diastolic blood pressure and higher adiponectin, a hormone made by fat tissue. CRP and 8-oxodG, a DNA-oxidation marker, showed non-significant downward trends (Nora 2023).

The evidence for nuts in general

The stronger evidence for nuts and heart health comes from studies of nuts in general, and they were not built around Brazil nuts:

Where Brazil nuts sit in the pooled lipid analyses

Meta-analyses and network meta-analyses comparing tree nuts on blood lipids have been published. None was among the records verified for this page, so this page makes no claim about how Brazil nuts ranked in them. What can be said from the verified record: Brazil nuts have been tested mostly in small trials, at very small doses and often without controls. That limits how much they can contribute to any pooled estimate. Results for nuts in general do not automatically carry over to a nut whose fat is about a quarter saturated and whose main distinctive nutrient is selenium.

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Selenium, Fat or Polyphenols? The Hypotheses

The explanations below are hypotheses the researchers proposed or that follow from their designs. None has been proven in people.

Animal and laboratory work (not evidence in people)

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What Is Not Known

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Who the Research Raises Cautions For

Allergy, aflatoxin and selenium-excess findings are covered on the main Brazil nuts page and the selenium overload and safety page.

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Connections

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Key Research Papers

  1. da Silva A, Silveira BKS, de Freitas BVM, et al. Effects of Regular Brazil Nut (Bertholletia excelsa H.B.K.) Consumption on Health: A Systematic Review of Clinical Trials. Foods (Basel, Switzerland). 2022;11(18). PubMed PMID: 36141050
  2. Carvalho RF, Huguenin GV, Luiz RR, et al. Intake of partially defatted Brazil nut flour reduces serum cholesterol in hypercholesterolemic patients--a randomized controlled trial. Nutrition journal. 2015;14:59. PubMed PMID: 26077768
  3. Huguenin GV, Oliveira GM, Moreira AS, et al. Improvement of antioxidant status after Brazil nut intake in hypertensive and dyslipidemic subjects. Nutrition journal. 2015;14:54. PubMed PMID: 26022214
  4. Donadio JLS, Rogero MM, Guerra-Shinohara EM, et al. SEPP1 polymorphisms modulate serum glucose and lipid response to Brazil nut supplementation. European journal of nutrition. 2018;57(5):1873-1882. PubMed PMID: 28501922
  5. Stockler-Pinto MB, Mafra D, Moraes C, et al. Brazil nut (Bertholletia excelsa, H.B.K.) improves oxidative stress and inflammation biomarkers in hemodialysis patients. Biological trace element research. 2014;158(1):105-12. PubMed PMID: 24504745
  6. Moriguchi Watanabe L, Bueno AC, de Lima LF, et al. Genetically determined variations of selenoprotein P are associated with antioxidant, muscular, and lipid biomarkers in response to Brazil nut consumption by patients using statins. The British journal of nutrition. 2022;127(5):679-686. PubMed PMID: 33947487
  7. Costa E Silva LM, Pereira de Melo ML, Faro Reis FV, et al. Comparison of the Effects of Brazil Nut Oil and Soybean Oil on the Cardiometabolic Parameters of Patients with Metabolic Syndrome: A Randomized Trial. Nutrients. 2019;12(1). PubMed PMID: 31877968
  8. Coutinho-Wolino KS, da Cruz BO, Cardozo LFMF, et al. Brazil nut supplementation does not affect trimethylamine-n-oxide plasma levels in patients with coronary artery disease. Journal of food biochemistry. 2022;46(8):e14201. PubMed PMID: 35467017
  9. Silveira BKS, Silva AD, Rocha DMUP, et al. Brazil Nut (Bertholletia excelsa H.B.K.) Consumption in Energy-Restricted Intervention Decreases Proinflammatory Markers and Intestinal Permeability of Women with Overweight/Obesity: A Controlled Trial (Brazilian Nuts Study). The Journal of nutrition. 2024;154(9):2670-2679. PubMed PMID: 39025334
  10. Duarte GBS, Reis BZ, Rogero MM, et al. Consumption of Brazil nuts with high selenium levels increased inflammation biomarkers in obese women: A randomized controlled trial. Nutrition (Burbank, Los Angeles County, Calif.). 2019;63-64:162-168. PubMed PMID: 31026738
  11. Reis BZ, Duarte GBS, Vargas-Mendez E, et al. Brazil nut intake increases circulating miR-454-3p and miR-584-5p in obese women. Nutrition research (New York, N.Y.). 2019;67:40-52. PubMed PMID: 31150916
  12. Bersch-Ferreira ÂC, Weschenfelder C, Vieira Machado RH, et al. Effects of mixed nuts as part of a Brazilian Cardioprotective diet on LDL-cholesterol in adult patients after myocardial infarction: a multicenter randomized controlled clinical trial. Nutrition journal. 2024;23(1):118. PubMed PMID: 39354558
  13. Nora CL, Zhang L, Castro RJ, et al. Effects of mixed nut consumption on LDL cholesterol, lipoprotein(a), and other cardiometabolic risk factors in overweight and obese adults. Nutrition, metabolism, and cardiovascular diseases : NMCD. 2023;33(8):1529-1538. PubMed PMID: 37263914
  14. Macan TP, de Amorim TA, Damiani AP, et al. Brazil nut prevents oxidative DNA damage in type 2 diabetes patients. Drug and chemical toxicology. 2022;45(3):1066-1072. PubMed PMID: 32811197
  15. Cardoso BR, Duarte GBS, Reis BZ, et al. Brazil nuts: Nutritional composition, health benefits and safety aspects. Food research international (Ottawa, Ont.). 2017;100(Pt 2):9-18. PubMed PMID: 28888463
  16. Vasquez-Rojas WV, Martín D, Miralles B, et al. Composition of Brazil Nut (Bertholletia excels HBK), Its Beverage and By-Products: A Healthy Food and Potential Source of Ingredients. Foods (Basel, Switzerland). 2021;10(12). PubMed PMID: 34945560
  17. Pereira E, Ferreira MC, Sampaio KA, et al. Physical properties of Amazonian fats and oils and their blends. Food chemistry. 2019;278:208-215. PubMed PMID: 30583364
  18. da Silva Costa N, Almeida PP, Da Cruz BO, et al. Supplementation of diet with Brazil nut modulates body composition, bone parameters, and lipid peroxidation in Wistar rats. Journal of food biochemistry. 2022;46(10):e14294. PubMed PMID: 35762459
  19. Menezes AC, Brito ML, Almeida PP, et al. Brazil nuts potential: effects on lipid peroxidation and heart health in nephrectomized rats. Journal of complementary & integrative medicine. 2024;21(3):340-348. PubMed PMID: 39146527
  20. Quitian-Useche YF, Sánchez-Ortiz BL, Borges SF, et al. Fatty ethanolamide of Bertholletia excelsa triglycerides (Brazil nuts): anti-inflammatory action and acute toxicity evaluation in Zebrafish (Danio rerio). Inflammopharmacology. 2021;29(5):1519-1537. PubMed PMID: 34498144
  21. Chen GC, Zhang R, Martínez-González MA, et al. Nut consumption in relation to all-cause and cause-specific mortality: a meta-analysis 18 prospective studies. Food & function. 2017;8(11):3893-3905. PubMed PMID: 28875220
  22. Estruch R, Ros E, Salas-Salvadó J, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. The New England journal of medicine. 2018;378(25):e34. PubMed PMID: 29897866
  23. Institute of Medicine (US) Panel on Dietary Antioxidants and Related Compounds. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. 2000. PubMed PMID: 25077263

PubMed Topic Searches

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