Antioxidants are chemical compounds that inhibit oxidation, a chemical reaction that can produce free radicals, which are unstable molecules capable of damaging cells through oxidative stress.
In the dietary context, antioxidants are crucial for neutralizing free radicals, thereby protecting lipids, proteins, and DNA from oxidative damage, which is associated with aging and the development of chronic diseases such as cancer, cardiovascular disease, and neurodegenerative disorders.
Key dietary antioxidants include vitamins C and E, carotenoids, polyphenols, and selenium, all of which act through various mechanisms to donate electrons or hydrogen atoms to stabilize free radicals, halting chain reactions of oxidative damage.
In food systems, antioxidants also play a functional role by preventing the oxidation of fats and oils, which can lead to rancidity and loss of nutritional value. For instance, vitamin C (ascorbic acid) is often added to processed meats to reduce the formation of nitrosamines during curing by interrupting oxidative pathways. Similarly, vitamin E (tocopherol) protects cell membranes and fatty acids from oxidation, and polyphenols in fruits, vegetables, and tea contribute to the stabilization of reactive oxygen species.
While antioxidants are widely regarded for their health benefits, their efficacy depends on various factors, including bioavailability, dietary source, and the balance of oxidative and antioxidative processes in the body. Excessive supplementation of antioxidants has shown mixed results in studies, sometimes disrupting natural oxidative signaling pathways and failing to confer additional benefits. Antioxidants should be primarily consumed through a balanced diet rich in fruits, vegetables, nuts, and whole grains.