Research & Your Health is a series of articles written in accessible, everyday language, focused on the latest scientific research of natural health products.
On November 16, 2015
Background: Brazil nuts have high levels of selenium, a mineral associated with antioxidant, anti-inflammatory and thyroid hormone metabolism. The balance between oxidation in the body and antioxidant compounds is important, because higher oxidative stress may be a precursor to diseases and conditions such as hypertension, dyslipidemia and diabetes.
Objective: The aim of this study was to investigate the effects that Brazil nut consumption have on the management of hypertension and dyslipidemia by improving antioxidant status.
Methods: This was a randomized, placebo-controlled, double-blind crossover study with 91 hypertensive and dyslipidemic patients (male and female) who had a mean age of 62 years. The trial consisted of two 12-week measurement periods (measurements performed at baseline, four weeks, eight weeks and 12 weeks of each 12-week period) with a four-week break in between (known as a washout period). Participants were randomized to an intervention (13 g per day of partially defatted granulated Brazil nut supplement, which is about 227.5 μg of selenium per day) or placebo-control group. Both groups also participated in an individualized diet based on balanced macronutrient intake, nutritional status, age and physical inactivity levels. Measurements included height, weight, body mass index (BMI), blood pressure, and blood samples assessing a number of antioxidant markers along with plasma selenium content, cholesterol and blood lipid profiles.
Results: The study found significant increases in plasma selenium levels for the intervention group and significantly higher antioxidant enzymatic reactions within the blood. Reduced oxidation of low-density lipoprotein (LDL) cholesterol was also lower among the intervention group. There were no changes among either group for body weight and BMI measures.
Conclusion: This study suggests that adding an appropriate amount of Brazil nuts to the diet is beneficial for the health of hypertensive and dyslipidemic patients, because of its altering of plasma selenium levels, antioxidant status and decreasing of LDL cholesterol levels.
Findings in Perspective: This study shows promise for helping to balance antioxidant levels in the plasma through food. Further research regarding selenium supplementation is warranted to further understand the mechanism for the success with Brazil nuts, and whether or not the same effect would be present between selenium supplementation and eating the whole food. For now, this study provides support for the addition of Brazil nuts to the diet of hypertensive and dyslipidemic patients.
Grazielle V.B. Huguenin, Glaucia M.M. Oliveira, Annie S.B. Moreira, et al. Nutrition Journal (2015), 14:54