 The evidence suggests that ROS can be beneficial for health when present at low levels, which is known as mito-hormesis. This phenomenon is triggered by various environmental factors such as calorie restriction, hypoxia, temperature stress, and physical activity, as well as by insulin-slash-IGF-1 receptor signaling, amp-dependent kinase, AMPK, activation, target of rapamycin, TOR, inhibition, and sirtuin regulation. Furthermore, interference with this signaling pathway by pharmaceuticals or natural compounds is often detrimental. This article was authored by Michael Risto and Catherine Schmeisser.