['Thyroid hormones can lower levels of atherogenic lipoproteins, and selenium is important in thyroid hormone homeostasis. We aimed to investigate the effects of a healthy diet associated with the Brazil nut (Bertholletia excelsa) in dyslipidemic and hypertensive patients.', 'This study was a randomized, placebo-controlled, double-blind trial. Seventy-seven dyslipidemic and hypertensive patients already receiving lipid-lowering drugs received either a dietary treatment associated with partially defatted Brazil nut flour (13 g/day providing 227,5 μg of selenium/day),or with dyed cassava flour as a placebo. All patients received a personalized dietary guideline with nutritional recommendations for dyslipidemia and hypertension and were followed for 90 days.', 'The Brazil nut group showed reductions in total cholesterol (-20.5\u2009±\u200961.2 mg/dL, P\u2009=\u20090.02), non HDL-cholesterol (-19.5\u2009±\u200961.2 mg/dL, P\u2009=\u20090.02) and Apo A-1 (-10.2\u2009±\u200926.7 mg/dL, P\u2009=\u20090.03) without significant alterations in the Apo B/Apo A-1 ratio. The placebo group showed a reduction in FT3 levels (-0.1\u2009±\u20090.4, P\u2009=\u20090.03) and increased Lp(a) levels (5.9\u2009±\u200918.0 mg/dL, P\u2009=\u20090.02). There were no statistical differences in blood pressure and serum lipids between Brazil nut and placebo group.'] Does intake of partially defatted Brazil nut flour reduce serum cholesterol in hypercholesterolemic patients -- a randomized controlled trial?