- Brazil nuts are high in selenium, an essential mineral with antioxidant and anti-inflammatory properties.
- A recent clinical trial suggests that consuming 8 grams of Brazil nuts daily may reduce inflammation and improve intestinal permeability in women with overweight or obesity.
- While experts say it’s likely safe and beneficial for most people to eat Brazil nuts, it’s advisable to limit consumption to 1–2 nuts per day to avoid selenium toxicity.
Brazil nuts are one of the richest sources of selenium, a mineral essential for antioxidant defense, immune function, and thyroid hormone metabolism.
Low selenium levels in the bloodstream are associated with several inflammatory conditions, including gut health issuesTrusted Source.
Additionally, previous studiesTrusted Source have highlighted connections between obesity, inflammation, and gut problems, like increased intestinal permeability, also known as leaky gut. Leaky gut is thought to develop as body fat and inflammation increases, the tight junctionsTrusted Source in the cells lining the intestines may loosen.
This allows more antigens, toxins, and bacteria to enter the bloodstream, triggering further inflammation and creating a cycle where obesity and intestinal permeabilityTrusted Source worsen each other.
A new study explored the impact of daily Brazil nut consumption on inflammation and intestinal permeability, focusing on women with overweight or obesity during an 8-week calorie-reduced diet.
Findings published in The Journal of Nutrition suggest that eating 8 grams of Brazil nuts per day may improve these health markers, likely due to their high selenium content.
Participants consumed organic Brazil nuts sourced from Amazonas (Brazil) and donated by ECONUT.
Medical News Today attempted to contact ECONUT regarding their involvement in providing Brazil nuts for the study. The company could not be reached for comment at the time of publication. Their support was not a reported conflict of interest.
Researchers from the Department of Nutrition and Health at Universidade Federal de Viçosa, Brazil, conducted an eight-week non-randomized controlled trial between June 2019 and September 2021. It involved 56 adult women ages 20–55, with an average age of 34.
Participants included those who were overweight with specific cardiometabolic risk factors (17.4%) or had obesity (82.6%), regardless of risk factors.
The researchers excluded people who were pregnant, lactating, in menopause, athletes, vegan, had certain medical conditions, were using specific medications, experienced significant weight changes, consumed nuts regularly, and had other potential study interferences.
They split participants into control and Brazil nut groups, both of which received customized menu options with about 500 fewer calories than their estimated daily needs.
The researchers’ macronutrient distribution was 50% carbohydrates, 30% fats, and 20% proteins, following established obesity management guidelines. They aimed for participants to lose at least 4 kilograms over 8 weeks.
The researchers also provided each group with controlled-ingredient salad dressings to balance fat and calorie intake between groups.
The diets were as follows:
- control group — followed a nut-free diet with 10 grams of soybean oil-based salad dressing with lemon daily
- Brazil nut group — consumed 8 grams of Brazil nuts (347.2 micrograms of selenium) as a morning snack and 5 grams of canola oil-based salad dressing with lemon daily.
A nutritionist provided individualized counseling and monitored diet adherence biweekly, including alcohol consumption. Participants who did not adhere to the study protocol were excluded from the final sample.
Researchers analyzed inflammatory markers in the blood and selenium levels. They also tested intestinal permeability using the lactulose/mannitol test (LM ratio).
They used statistical analyses to assess group changes and relationships among the variables, with a 97% power to detect differences in intestinal permeability.
Of the 56 recruited women, 46 (82.1%) were included in the final sample. At baseline, the control group had a higher intake of polyunsaturated fats than the Brazil nut group.
During the intervention, the control group had reduced saturated fat, while the Brazil nut group increased their intake of polyunsaturated fats and dietary fiber.
Both groups achieved similar calorie restrictions, weight loss (about 3 kilograms), and small reductions in waist circumference.
The researchers noted that the group consuming Brazil nuts showed a significant increase in selenium levels compared to the control group, demonstrating adherence to their Brazil nut intake.
Compared to the control group, the Brazil nut group also exhibited lower values of inflammatory markers, including C-reactive protein, tumor necrosis factor, interleukin-1β (IL1-β)Trusted Source, and interleukin-8 (IL-8), indicating an improvement in systemic inflammation.
In the Brazil nut group, C-reactive protein levels decreased from 7.1 mg/L to 5.6 mg/L at the end of 8 weeks. In contrast, the control group saw an increase from 8.0 to 9.4 mg/L. The mechanism behind the changes in C-reactive protein levels remains unclear, but they may be linked to intestinal permeability and gut inflammation.
Additionally, women in the Brazil nut group who lost more weight showed more significant reductions in C-reactive protein levels.
The Brazil nut group also showed lower lactulose excretion and LM ratio values, indicating slightly improved intestinal permeability markers compared to the control group. However, the changes were statistically similar across both groups.
In further analyses, researchers found that higher blood selenium levels were linked to lower inflammation markers, particularly IL1-β and IL-8, with IL-8 also relating to changes in the LM ratio. These results suggest selenium levels could predict shifts in markers of systemic inflammation and gut permeability.
