Oxidative stress

Oxidative stress is an imbalance in which reactive oxygen molecules outpace the body's antioxidant defenses, damaging lipids, proteins and DNA.

Cells produce reactive oxygen species constantly as a by-product of making energy in mitochondria, and immune cells make them deliberately to kill microbes. Enzymes such as superoxide dismutase and catalase, along with glutathione and dietary antioxidants, normally neutralize them. When production rises, from inflammation, smoking, radiation, certain toxins or intense exercise, or when defenses fall, the surplus reacts with cell components; the resulting damage accumulates with age and contributes to atherosclerosis, neurodegeneration and cancer.

Oxidative stress is measured indirectly, through markers such as malondialdehyde, 8-OHdG or the ratio of reduced to oxidized glutathione, since the reactive species themselves last only fractions of a second. Large trials of antioxidant vitamins have generally not improved health outcomes, a reminder that the biology is more complex than simple scavenging. CBD shows antioxidant activity in chemical and cell-based experiments; whether that has any clinical significance is unresolved.