Scientists have discovered that Brazil nuts may have anti-inflammatory effects on gut health. Max Oppenheim/Getty ImagesBrazil nuts are rich 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 overweight or obese women. Experts say that while eating Brazil nuts is likely safe and beneficial for most people, it is best to limit nut intake to one or two a day to avoid selenium toxicity. states.
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 intestinal health issues.
Additionally, previous research has highlighted the link between obesity, inflammation, and intestinal problems such as increased intestinal permeability, also known as leaky gut. Leaky gut is thought to develop when body fat and inflammation increase, loosening the tight junctions in the cells lining the intestines.
This creates a cycle in which more antigens, toxins, and bacteria enter the bloodstream, causing further inflammation and mutually worsening obesity and intestinal permeability.
A new study focused on overweight or obese women on an 8-week calorie reduction diet and investigated the effects of daily Brazil nut consumption on inflammation and intestinal permeability.
Research published in The Journal of Nutrition suggests that eating 8 grams of Brazil nuts a day may improve these health markers, likely due to their high selenium content. Masu.
Participants ate organic Brazil nuts from Amazonas (Brazil) donated by ECONUT.
Medical News Today attempted to contact ECONUT about its involvement in donating Brazil nuts to the study. There was no comment from the company at the time of article publication. Their support had no reported conflicts of interest.
Researchers from the Department of Nutrition and Health at the Federal University of Viçosa in Brazil conducted an eight-week non-randomized controlled trial from June 2019 to September 2021. The study involved 56 adult women between the ages of 20 and 55, with an average age of 34.
Participants included those who were overweight (17.4%) or obese (82.6%) due to specific cardiometabolic risk factors, regardless of risk factors.
Researchers found that people who regularly consume nuts include those who are pregnant, breastfeeding, menopausal, athletes, vegans, have certain medical conditions, take certain medications, have significant weight changes, and those who regularly consume nuts. We excluded those who were currently working on the project, as well as those who might interfere with the research.
Researchers divided participants into a control group and a Brazil nut group, with both groups receiving a customized menu option that contained approximately 500 fewer calories than their estimated daily calorie needs.
The researchers’ macronutrient distribution was 50% carbohydrate, 30% fat, and 20% protein, in accordance with established obesity management guidelines. They aimed for participants to lose at least 4 kilograms in 8 weeks.
The researchers also provided each group with ingredient-controlled salad dressings to balance fat and calorie intake between groups.
The diet was as follows:
Control group — Brazil nuts group following a nut-free diet consuming 10 grams of soybean oil-based salad dressing with lemon daily — 8 grams of Brazil nuts (347.2 micrograms of selenium) and 5 grams of canola oil-based salad as a morning snack Consume lemon dressing daily.
A nutritionist provided individual counseling and biweekly monitoring of dietary compliance, including alcohol intake. Participants who did not follow the study protocol were excluded from the final sample.
The researchers analyzed inflammatory markers and selenium levels in the blood. They also tested intestinal permeability using the lactulose/mannitol test (LM ratio).
They used statistical analysis to assess group changes and relationships between variables and had 97% power to detect differences in intestinal permeability.
Of the 56 women recruited, 46 (82.1%) were included in the final sample. At baseline, the control group had a higher intake of polyunsaturated fat than the Brazil nut group.
During the intervention, saturated fat decreased in the control group, while polyunsaturated fat and dietary fiber intake increased in the Brazil nut group.
Both groups achieved similar caloric restriction, weight loss (approximately 3 kilograms), and modest reductions in waist circumference.
The researchers noted that the group that consumed Brazil nuts showed a significant increase in selenium levels compared to the control group, indicating compliance with their Brazil nut intake.
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 mg/L to 9.4 mg/L. The mechanism behind changes in C-reactive protein levels is still unclear but may be related to intestinal permeability and intestinal inflammation.
Additionally, women in the Brazil nut group who lost more weight showed a more pronounced reduction in C-reactive protein levels.
Additionally, the Brazil nut group had lower values of lactulose excretion and LM ratio, indicating slightly improved intestinal permeability markers compared to the control group. However, the changes were statistically similar in both groups.
In further analysis, the researchers found that increased blood selenium levels were associated with decreased inflammatory markers, particularly IL1-β and IL-8, with IL-8 also associated with changes in the LM ratio. I discovered it. These results suggest that selenium levels can predict changes in markers of systemic inflammation and intestinal permeability.
This study had a small sample size and short duration. This study was limited to young and middle-aged women recruited in Brazil, so the findings may not be generalizable to other populations.
Study participants were blinded to the intervention, were not randomized, and were unable to follow the intended caloric restriction. Additionally, dietary compliance is primarily monitored through self-reporting, which is subject to error.
Alyssa Simpson, RDN, CGN, CLT, registered dietitian, certified gastrointestinal nutritionist, and owner of Nutrition Resolution in Phoenix, Arizona, who was not involved in the study, isolated dietary variables. We call for further research to clarify their effects and interactions.
She told Medical News Today that “the results of this study show that selenium in Brazil nuts has a significant impact on inflammation and intestinal permeability,” but that “a simultaneous increase in polyunsaturated fat and fiber intake , which complicates attributing the effect solely to selenium.”
“More controlled study designs that treat selenium, polyunsaturated fat, and fiber as separate interventions could help identify how each factor independently influences inflammation and gut health. “Sho,” she suggested.
Dr. Simpson explained that Brazil nuts may reduce inflammation and improve gut health in overweight or obese women on calorie-restricted diets, primarily due to their high selenium content.
“Selenium acts as a powerful antioxidant, increasing selenoproteins that neutralize oxidative stress and reduce pro-inflammatory cytokines, thereby improving intestinal permeability. Nuts contain polyunsaturated fats. and fiber, which independently support anti-inflammatory processes and gut health and possibly act synergistically with selenium.”
— Alyssa Simpson, RDN, CGN, CLT
MNT also spoke to Thomas M. Holland, MD, MSc, a physician-scientist and assistant professor in the Institute for Healthy Aging, School of Health Sciences, RUSH University, who was not involved in the study.
He gave a similar explanation of the mechanism underlying the study results, saying, “In this study, increased selenium levels correlated with decreased inflammatory cytokines such as IL-8 and IL1-β and improved intestinal permeability. “This could lead to more complete absorption.” Digested food. ”
“Given the ubiquitous role of selenium in inflammatory pathways, the effects may also apply to men, but further studies will be needed to confirm this,” he said.
Kiran Campbell, RDN, a registered dietitian and medical nutrition advisor at Dietitian Insights, who was not involved in the study, told MNT that our bodies cannot produce selenium.
Therefore, you should get your selenium from animal-based sources such as fish, seafood, poultry, and meat, or plant-based sources such as sunflower seeds and Brazil nuts, she said.
Professor Campbell pointed out that one Brazil nut (about 5 grams) contains about 96 micrograms of selenium, which is almost double the recommended daily intake of 55 micrograms for most adults. .
Still, Simpson says the general recommendation for most people is about one to two Brazil nuts per day, which is consistent with the National Institutes of Health’s safe upper limit of 400 micrograms per day. It is said that there is
However, she warned, “If you consume more than four or five Brazil nuts each day, you are at risk of exceeding this limit.”
Campbell highlighted that EFSA’s Panel on Nutrition, Novel Foods and Food Allergens (NDA) has set a recommended upper limit for selenium in 2023 of up to 255 micrograms per day for adult men and women.
She advises monitoring your selenium intake from supplements and foods to avoid selenium toxicity, especially if you regularly consume Brazil nuts or other sources of selenium.
Symptoms of selenium toxicity include “brittle nails, hair loss, rashes, and intestinal and nerve problems,” Campbell said.
Ultimately, both nutritionists and Holland believe it’s practical to consciously incorporate one to two Brazil nuts per day, as they may help reduce inflammation and improve gut health. suggests that it may be beneficial.
For those wondering which type of Brazil nuts to buy, organic, raw nuts may be the best choice, but the nutritional differences between raw and roasted nuts may be minimal.
Experts stressed that Brazil nuts should not be considered as a standalone solution. Instead, it should be included along with other gut health-promoting foods as part of a healthy eating pattern, such as the Mediterranean or MIND diets.
