Antioxidaní

Antioxidaní, commonly called antioxidants, are substances that inhibit oxidation, a chemical process that can produce free radicals and damage cells. They help protect biomolecules such as lipids, proteins, and DNA from oxidative stress, which has been linked to aging and several chronic diseases.

Biological antioxidants come from two main sources: endogenous systems produced by the body and exogenous compounds obtained from the diet. Endogenous defenses include enzymes such as superoxide dismutase, catalase, and glutathione peroxidase, along with non-enzymatic components like glutathione and uric acid. Dietary antioxidants include vitamins C and E, carotenoids (such as beta-carotene, lycopene, and lutein) and a broad range of polyphenols found in fruits, vegetables, tea, coffee, nuts, seeds, and whole grains.

Mechanisms involve donating electrons to neutralize reactive oxygen species, interrupting radical chain reactions, and aiding in the regeneration of other antioxidants through redox cycling.

Health context: Diets rich in antioxidant-containing foods are associated with lower risks of certain chronic diseases, particularly cardiovascular disease and some cancers. However, randomized trials of antioxidant supplements have largely failed to show clear benefits and, in some cases, have indicated potential harm at high doses (for example, beta-carotene in smokers or high-dose vitamin E). This evidence supports obtaining antioxidants primarily through a balanced diet rather than high-dose supplements.

Safety and regulation: Most dietary antioxidants are considered safe when consumed in normal amounts via food. Supplements can interact with medications and may not be suitable for everyone, so guidance typically favors dietary patterns—fruits, vegetables, and whole grains—over megadoses of pills.