Antioxidants and Their Physiologic Role
Antioxidants are substances that reduce oxidative damage by neutralizing reactive oxygen species (ROS) or by interrupting oxidative chain reactions. Antioxidants help protect cells from injury caused by oxidative stress.
Types of Antioxidants
Dietary antioxidants include vitamins (such as vitamin C and vitamin E) and minerals (such as selenium), plus antioxidant compounds found in plants (such as polyphenols). Endogenous antioxidants are produced within the body, including glutathione and antioxidant enzymes (such as superoxide dismutase and catalase).
Mechanisms of Antioxidant Action
Antioxidants can directly scavenge free radicals, reducing ROS activity. Antioxidants can also limit ROS production or enhance cellular antioxidant defenses through enzyme regulation.
What Antioxidants Do in Cells
Oxidative stress can damage lipids, proteins, and DNA. By lowering ROS activity, antioxidants reduce oxidative damage and support normal cellular function.
Clinical Context of Antioxidant Effects
Antioxidant effects can be measured in laboratory assays, such as reduced markers of oxidative stress. Clinical outcomes depend on the underlying disease process, baseline antioxidant status, and the specific antioxidant source or formulation.
Antioxidant Supplements and Evidence Limitations
Supplement use does not consistently translate into improved clinical outcomes across populations and diseases. Some large trials have shown no benefit or potential harm with certain high-dose antioxidant supplements in specific settings.