Brazil nuts may help women who are overweight or obese tackle low-level chronic inflammation and improve their gut health, according to recent research from the Federal University of Vicosa, Brazil.
Inflammation is a process used by the immune system to fight off diseases, infections and viruses, but for some people, it can remain slightly elevated, and this low-level inflammation has been linked to a number of chronic diseases, including obesity, heart disease, type 2 diabetes and dementia.
Oxidative stress can contribute to this type of inflammation. That is where byproducts of chemical reactions, called free radicals, cause damage to cells in the body.
But antioxidants can neutralize free radicals. Selenium is a mineral which has antioxidant properties, meaning it can have this effect, and Brazil nuts contain a lot of selenium.
Brazilian nutrition scientists tested the effect of selenium-rich Brazil nuts on 56 women, aged 20 to 55, all of whom were overweight or obese, to see whether it had an impact on their weight-related inflammation.
Over the course of eight weeks, half of the women followed a calorie-restricted diet without any nuts, and the other half followed the same diet plus two servings of Brazil nuts per day.
The scientists took samples of their blood and urine at the beginning and end of the study to measure markers of inflammation and gut health.
After eight weeks, the scientists found that those who had eaten the Brazil nuts lost more weight than those who did not: an average of 7.7 pounds compared to 5.5 pounds.
Those who had eaten Brazil nuts improved their inflammation too. When looking at a protein called C-reactive protein (CRP), which is one way the scientists measured inflammation, they found significant improvements in the Brazil nut group and deterioration in the non-nut group.
Specifically, at the start of the trial, 24 percent of both groups had healthy levels of CRP, but by the end, this applied to 36 percent of the Brazil nut group, and just 4.7 percent of the non-nut group, suggesting inflammation got better for the former and worse for the latter.
Women in the Brazil nut group who lost more weight seemed to improve their inflammatory markers more, with greater improvements in their CRP levels, but even those who did not lose as much weight had better levels on average than those who did not eat nuts.
The scientists also investigated what happened to the women's gut health. Obesity can increase the risk of intestinal permeability, where substances can travel from the gut into the bloodstream—another route to inflammation.
Selenium-rich Brazil nuts, the nutrition scientists proposed, might be able to improve this too.
They did find that eating Brazil nuts was connected with an increased intake of fiber, which is associated with improved gut health, including more regular bowel movements and more abundant microbial communities.
And there was a small improvement in gut health in the Brazil nut group, inferred from markers in the women's urine—however, the scientists said this effect was modest, and more research was needed to confirm the effect of Brazil nuts on the gut.
They concluded that eating Brazil nuts could be a promising dietary strategy for women looking to improve their inflammation levels while losing weight, and that potential benefits were linked to the mineral selenium.
This study was published in the Journal of Nutrition in September.
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Reference
Souza Silveria, B. K., da Silva, A. Rocha, D. M. U. P., Waskow, K., Duarte Martino, H. S., Bressan, J., Hermsdorff, H. H. M. (2024). 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 154(9). https://doi.org/10.1016/j.tjnut.2024.07.016
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