Systemic subchronic toxicity and comparison of four selenium nutritional supplements by 90-day oral exposure in Sprague-Dawley rats

To evaluate and compare the safety of four selenium supplements, namely Se-enriched peptides (SeP), yeast selenium (SeY), L-Se-methylselenocysteine (L-SeMc) and sodium selenite (Na2SeO3), the subchronic toxicity study was designed by 90-day gavage administration in Sprague-Dawley rats. The doses of SeP, SeY, L-SeMc and Na2SeO3 were 0.15, 0.30 and 0.60 mg/kg bw/day, with additional dose of 0.45 mg/kg L-SeMc (All dose calculated as Se). Symptoms like growling, hair loss and significant weight loss were found at 0.60 mg/kg of L-SeMc, but not in other groups. At the dose of 0.60 mg/kg, females in Na2SeO3, SeY and L-SeMc groups showed significant elevations in ALT and/or ALP. Pathologic manifestations such as bile duct hyperplasia and cholestasis were predominantly found in females at 0.6 mg/kg of L-SeMc and SeY groups, and in males at same dose of L-SeMc group showed marked testicular atrophy. 0.60 mg/kg of SeY and Na2SeO3, and 0.30, 0.45, 0.60 mg/kg of L-SeMc induced significant reductions in sperm motility rates, rapid movement and amount. In conclusion, the NOAEL of SeP, SeY, L-SeMc, Na2SeO3 was all 0.30 mg/kg for female, and 0.60, 0.30, 0.15 and 0.30 mg/kg for male respectively. Liver and reproductive organs are possible toxic target organs of hyper selenium.