Brazil nut effects on health in clinical trials
What it found
In 24 clinical trials in people, eating Brazil nuts regularly raised selenium and antioxidant markers, and improved some lipid, glucose and other health markers.
Benefits varied with the person's health status and the selenium content of the nuts.
What they found
Studies in people
Antioxidant status
All studies that checked antioxidant status found improvements, with higher selenium levels and/or glutathione peroxidase activity in plasma, serum, whole blood and/or red blood cells. This was seen regardless of the health status of the people studied.
Healthy subjects
Healthy subjects improved lipid markers and fasting glucose. Regular consumption lasted 15 days to 12 weeks, with 1 to 11 units a day providing 48 to 862.65 micrograms of selenium.
Obesity
People with obesity improved markers of lipid metabolism. In one study, three to five units a day for 16 weeks reduced total cholesterol, triglycerides and oxidized LDL, and increased red blood cell velocity in adolescents with obesity.
Diabetes and dyslipidemia
People with type 2 diabetes or dyslipidemia improved oxidative stress or DNA damage markers. In one study, one unit a day for 24 weeks increased glutathione peroxidase activity and selenium, and reduced malondialdehyde and creatine kinase in people taking statins.
Hemodialysis
People on hemodialysis benefited greatly, with improvements in lipid profile, oxidative stress, inflammation and thyroid function. One unit a day for three months raised selenium and glutathione peroxidase, and lowered inflammatory and oxidative stress markers.
Mild cognitive impairment
Older adults with mild cognitive impairment improved verbal fluency and constructional praxis after one unit a day for 24 weeks. Selenium status was positively correlated with a cognitive test score.
Coronary artery disease
Results on a marker of lipid peroxidation were controversial in people with coronary artery disease. No significant changes were found in some other markers of lipid metabolism and inflammation.
What the authors conclude
“Nowadays, scientific evidence supports the health benefits of regular BN consumption in a free-living habitual diet.”
Also in their conclusions
- They conclude that scientific evidence supports the health benefits of regular Brazil nut consumption in a free-living habitual diet.
- They say these benefits seem to vary according to the health status of the subjects, the selenium content of the Brazil nuts, the selenium levels of the participants before the intervention, and the presence of some polymorphisms.
- They report that the benefits of Brazil nut consumption were found in different action pathways.
How it was done
The authors say the Brazil nut is a promising food with many reported health benefits, but the scientific evidence had not been systematically reviewed.
They searched three databases for clinical trials of regular Brazil nut consumption and included 24 studies, of which 15 were non-randomized. In all studies, Brazil nuts were eaten as whole seeds in a habitual free-living diet.
What it can’t tell you
- Most of the studies were not randomized, so they cannot prove that Brazil nuts caused the changes seen.
- The studies used different amounts of Brazil nuts and lasted different lengths of time, so the best dose and duration are not clear.
- The evidence is limited for people with diabetes, dyslipidemia or coronary artery disease because few studies included them.
Who paid
- Funding
- Funded by Coordenação de Aperfeicoamento de Pessoal de Nível Superior; National Council for Scientific and Technological Development; Fundação de Amparo à Pesquisa do Estado de Minas Gerais (from the PubMed record).
- Conflicts
- The authors declare no conflicts of interest.
- Authors work at
- Laboratory of Energy Metabolism and Body Composition, Brazil; Institute of Public Policies and Sustainable Development, Brazil
The paper
- Title
- Effects of Regular Brazil Nut ( Bertholletia excelsa H.B.K.) Consumption on Health: A Systematic Review of Clinical Trials
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- da Silva A, Silveira BKS, de Freitas BVM, Hermsdorff HHM, Bressan J (2022). Effects of Regular Brazil Nut ( Bertholletia excelsa H.B.K.) Consumption on Health: A Systematic Review of Clinical Trials. Foods (Basel, Switzerland). doi:10.3390/foods11182925Free full textPubMed 36141050DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error