Improvement of antioxidant status after Brazil nut intake in hypertensive and dyslipidemic subjects

Randomized, double-blind crossover trial in adults with hypertension and dyslipidemia receiving nutrition counseling and drug therapy at a cardiology prevention clinic in Rio de Janeiro, Brazil. A total of 125 participants were randomized and 91 completed all stages; among completers, mean age was 62.1 ± 9.3 years and 51.6% were men.

Partially defatted granulated Brazil nut was given orally at 13 g/day for 12 weeks, providing about 227.5 μg of selenium on average. The comparator was 10 g/day of flavored cassava flour placebo in a randomized double-blind crossover design with a 4-week washout.

Daily Brazil nut intake improved antioxidant status overall. Compared with placebo, GPx3 increased by 24.8% with Brazil nut (p = 0.034), and 12-week total antioxidant capacity was higher (p = 0.024). Oxidized LDL was lower during the Brazil nut period and showed an inverse association with GPx3 after adjustment (p = 0.008), supporting reduced oxidative stress. 8-epi PGF2α did not show a clear between-group difference. The authors concluded that Brazil nut may be a useful addition to a heart-healthy diet for hypertensive and dyslipidemic patients.

Only 91 of 125 randomized participants completed all stages, and the crossover design raises the possibility of carryover effects despite a 4-week washout. The study was conducted in a single clinic population under concurrent diet and drug therapy, limiting generalizability. Some oxidative stress markers did not change consistently, including 8-epi PGF2α.