Selenium-Biofortified Strawberries Improve Glucose Homeostasis and Hepatic Function: A 30-Day Randomized Controlled Trial in Healthy Adults

Background: Selenium is an essential trace element for humans that plays a key role in glucose homeostasis and hepatic function. Biofortification is a sustainable agricultural technique able to increase micronutrients and reduce pesticides in crops. Purpose: The present study aimed to examine whether the consumption of strawberries biofortified with selenium in a healthy population for 30 days would increase the endogenous selenium concentration, and whether and to what extent it would impact glucose homeostasis and hepatic function. Methods: Thirty-five healthy participants, male and female, were divided by double-blinding into three different groups that received control strawberries (100 g/day), selenium-biofortified strawberries (100 g/day) or selenium in tablets (100 µg/day) for 30 consecutive days. Blood samples were collected at the beginning (T0, baseline) and at the end of the nutritional intervention (T1), and the groups were compared for differences in serum selenium concentrations, glucose homeostasis aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), and albumin (ALB). Results: Biofortification increased the selenium concentration in strawberries by 419%. Supplementation with biofortified strawberries increased serum selenium levels by about 73.6%, while standard selenium supplementation showed no statistically significant effect. Selenium-biofortifies strawberries reduced fasting glucose and insulin, and improved insulin sensitivity and β cell function. They also reduced AST and GGT within the physiological range. Conclusions: These data suggest that supplementation for 30 days with selenium-biofortified strawberries is safe and is associated with favourable changes in markers of glucose regulation. Selenium supplementation, at the standard market dose of 100 µg/day, demonstrated no significant clinical differences during the studied period.