Circulating compounds such as drugs and nutritional components might adhere to the oxygenator fibers and tubing during ECMO support. This study evaluated the amount of nutritional supplements adsorbed to the ECMO circuit under controlled ex vivo conditions. Six identical ECMO circuits were primed with fresh human whole blood and maintained under physiological conditions at 36 °C for 24 h. A dose of nutritional supplement calculated for a 70 kg patient was added. 150 mL volume was drawn from the priming bag for control samples and kept under similar conditions. Blood samples were obtained at predetermined time points and analyzed for concentrations of vitamins, minerals, lipids, and proteins. Data were analyzed using mixed models with robust standard errors. No significant differences were found between the ECMO circuits and the controls for any of the measured variables: cobalamin, folate, vitamin A, glucose, minerals, HDL cholesterol, LDL cholesterol, total cholesterol, triglycerides or total proteins. There was an initial decrease and then an increase in the concentration of cobalamin and folate. Vitamin A concentrations decreased in both groups over time. There was a decrease in concentration of glucose and an increased concentration of lactate dehydrogenase over time in both groups. There were no significant alterations in the concentrations of nutritional supplements in an ex vivo ECMO circuit compared to control samples. The time span of this study was limited, thus, clinical studies over a longer period of time are needed.