In non-stimulated conditions and in the presence of a pro-oxidant (t-BOOH), the fermented T. pratense sprout extracts decreased the ROS production in breast adenocarcinoma ER-+ and ER− cells and in human umbilical vein endothelial cells to a lesser extent (approximately 20–40%) than what we observed in our study (30–65%) for MCF-7 cells. The gene discussed is ESR1; the disease is breast adenocarcinoma.