Free Radical Threshold Value: A New Universal Body Constant.

Three evolutionary sources create 'primary' reactive oxygen species (ROS) and 'secondary' lipid oxygen species (LOS), forming the human body's 'free radical ground state'. We present evidence for the existence of a universal free radical threshold value (FRTV), defining the borderline between advantageous and adverse effects of free radicals observed above the free radical ground state. Based on standard vitamin D doses, the calculated amount of ∼3.5 × 10(12) rad/mg ROS/LOS tissue represents the tolerated number of free radicals in skin tissue - defined as FRTV. By means of quantitative ESR x-band spectroscopy, the FRTV was experimentally verified using ex vivo human skin irradiated with ultraviolet + visible (UV + VIS), UVB + UVA and VIS light. In addition, we investigated whether this threshold is also existent in internal organs by extending our experiment to fresh porcine liver. Based on the determination of ROS/LOS below and above the FRTV, ROS > LOS was characterized as beneficial and LOS > ROS as deleterious to the organism, respectively. Results of the experiments using porcine liver confirmed the appearance of the FRTV at radical generation ∼3.5 × 10(12) rad/mg. The relation ROS/LOS before and after the FRTV was consistent with the results determined for the skin. We conclude that the FRTV, theoretically calculated and experimentally confirmed, should be considered as a new 'universal body constant'.