Patients presenting with renal failure who are also dialysis-dependent frequently evince a deficiency of vitamins and minerals. During dialysis, the function of the kidneys, i.e. the elimination of toxins from the blood, is supplanted – although this happens outside the body. The disadvantage is that it is not just toxins that are filtered out of the blood but also vital substances, such as vitamins and minerals. As is the trace element selenium. Dialysis patients often have a selenium deficiency that can result in hypothyroidism, muscular disease, skin disorders, myocardial weakness and the loss of red blood corpuscles. As a free radical scavenger, selenium plays an important role in protecting cell membranes against oxidation. Thus, selenium protects by reducing oxidative stress in the body before the occurrence of cardiovascular disease. The objective of the study described below was to investigate the effect of Brazil nuts on the selenium levels of dialysis patients. Among all foodstuffs, Brazil nuts constitute the best known sources of selenium. In addition to selenium levels, the activity of the enzyme glutathione peroxidase was also investigated. The enzyme occurs in red blood corpuscles and assumes an important, protective function specific to the cells. Selenium is an essential component of this enzyme. Reduced activity results in damage to red blood corpuscles. A total of 81 Brazilian patients participated in the study. Each patient received one Brazil nut a day, weighing approximately 5 grams and containing 290.5 micrograms of selenium, over a period of three months. The measurements showed that the selenium levels of the patients increased from poor selenium values prior to commencement of the study to normal values owing to the additional consumption of Brazil nuts. A total of 11% of the study participants evinced reduced glutathione peroxidase activity prior to commencement of the study. After the addition of Brazil nuts, all patients exhibited normal enzyme activity. Based upon the study, it can be concluded that dialysis patients can counteract a possible selenium deficiency by consuming just one Brazil nut every day and can improve their antioxidative status.
Stockler-Pinto MB, Mafra D, Farage NE, Boaventura GT, Cozzolino SM: Effect of Brazil nut supplementation on the blood levels of selenium and glutathione peroxidase in hemodialysis patients. Nutrition. 2010, Nov-Dec; 26 (11-12): 1065-9.