Renal Nutrition Forum A Peer Reviewed Publication of the Renal Dietitians Dietetic Practice Group

Selenium is an integral part of the human antioxidant system. Both hemodialysis (HD) and peritoneal dialysis (PD) patients are deficient in selenium and its subsequent enzymes, compared to a healthy population. Few selenium supplementation trials have been conducted to evaluate its effect on enzymes, markers of peroxidation and clinical health outcomes in dialysis patients. Introduction Selenium is one of those trace elements that only gets one lecture (maybe even half of a lecture) during advanced micronutrient metabolism, and is soon forgotten after an exam is given. The complexity of nutrition as a whole does not allow enough time to thoroughly give each micronutrient its due diligence. For renal dietitians, there is an extreme focus on phosphorus, sodium, potassium and protein (to name a few), leaving little time to explore other nutrients, including selenium. It is widely accepted that compared to healthy individuals, a selenium deficiency is present in both hemodialysis and peritoneal dialysis patients, and that peritoneal dialysis (PD) patients experience a greater deficiency compared to hemodialysis (HD) patients (1, 7, 8, 9). This deficiency could be a contributor to cardiovascular disease (CVD) and ultimately, mortality. Selenium Selenium Nutriture Selenium is a mineral required for multiple functions in the human body, most notably, as an antioxidant (10). Dietary selenium is found as both organic and inorganic forms. Organic forms (selenomethionine and selenocysteine), are found in plant and animal products, respectively. More specifically, selenium replaces the sulfur found in the sulfur containing amino acids methionine and cysteine, resulting in selenomethionine and selenocysteine (Figure 1). Selenium is incorporated from the soil into the growing plant, resulting in varying levels of selenium, determined by the selenium content of the soil; this can be up to a ten-fold difference (1, 12). Consequently, the animal consuming the plant will also have varying amounts of selenium as a result of the selenium soil content (11, 12). The inorganic forms of selenium are selenide, selenite and selenate. They are found in a few vegetables but are mainly found in supplements, usually as selenite, selenate and selenomethionine (10). All forms of dietary selenium have a relatively high bioavailability. More specifically, approximately 80% of selenomethionine and selenocysteine are – Continued on page 3.