Figure 4.

Factors affecting the balance between ROS production and scavenging. A, In traditional lifestyles, ROS are derived from the metabolism of endogenous and exogenous (i.e., natural dietary) substances. The skin, especially its sweat glands, may play an important antioxidant role. B, In modern lifestyles, dietary xenobiotics have significantly increased, while the skin functions, especially sweat-mediated excretion, is decreased due to sedentary lifestyles. As a result, an imbalance between ROS production and the body’s antioxidant defense system takes place. OK, antioxidant defense capacity > ROS production; OS, oxidative stress.