Exogenous antioxidants, such as vitamins C and E, carotenoids, and polyphenols, play a critical role in maintaining cellular redox balance. At physiological doses, they help prevent oxidative stress by neutralizing reactive oxygen species (ROS). However, at high doses, they may exhibit prooxidant effects, potentially causing cellular damage. This review discusses the dual nature of exogenous antioxidants, highlighting their beneficial and harmful effects depending on dosage and context. Antioxidants are essential for protecting cells from oxidative damage, but their effectiveness depends on their concentration and the presence of other compounds. High concentrations of isolated antioxidants can be toxic, as they may react with beneficial ROS or increase the production of harmful radicals. For example, quercetin, a common antioxidant, can act as a prooxidant at high doses, increasing ROS production and causing cellular damage. The balance between oxidation and antioxidation is crucial for cellular function. While exogenous antioxidants are necessary for maintaining redox homeostasis, their high doses can disrupt this balance, leading to oxidative stress and potential disease. Studies show that dietary antioxidants, such as those found in fruits and vegetables, are generally safe and beneficial when consumed in their natural form. However, isolated supplements may have adverse effects due to their high concentrations. In vivo studies indicate that long-term consumption of natural food items like apples, olive oil, and honey can reduce oxidative stress and improve cognitive function. Animal experiments also show that certain antioxidants can reverse oxidative stress toxicity in rat models. However, synthetic antioxidants like BHA and BHT, when consumed in high doses, can be toxic and may even have anticarcinogenic effects. Epidemiological studies suggest that diets rich in antioxidants, such as fruits and vegetables, are associated with lower risks of chronic diseases like cancer and cardiovascular disease. However, individual supplementation trials have shown mixed results, with some studies indicating potential toxicity at high doses. This highlights the importance of consuming antioxidants in their natural food matrices, where they are more effective and safer. In conclusion, while exogenous antioxidants are beneficial at physiological doses, their high doses can be harmful. The safest and most effective way to obtain antioxidants is through a balanced diet rich in fruits, vegetables, and other natural sources. Supplementation should be approached with caution, as isolated high-dose antioxidants may have adverse effects. The complex interactions between antioxidants and other compounds in natural foods make them more effective and safer than isolated supplements.Exogenous antioxidants, such as vitamins C and E, carotenoids, and polyphenols, play a critical role in maintaining cellular redox balance. At physiological doses, they help prevent oxidative stress by neutralizing reactive oxygen species (ROS). However, at high doses, they may exhibit prooxidant effects, potentially causing cellular damage. This review discusses the dual nature of exogenous antioxidants, highlighting their beneficial and harmful effects depending on dosage and context. Antioxidants are essential for protecting cells from oxidative damage, but their effectiveness depends on their concentration and the presence of other compounds. High concentrations of isolated antioxidants can be toxic, as they may react with beneficial ROS or increase the production of harmful radicals. For example, quercetin, a common antioxidant, can act as a prooxidant at high doses, increasing ROS production and causing cellular damage. The balance between oxidation and antioxidation is crucial for cellular function. While exogenous antioxidants are necessary for maintaining redox homeostasis, their high doses can disrupt this balance, leading to oxidative stress and potential disease. Studies show that dietary antioxidants, such as those found in fruits and vegetables, are generally safe and beneficial when consumed in their natural form. However, isolated supplements may have adverse effects due to their high concentrations. In vivo studies indicate that long-term consumption of natural food items like apples, olive oil, and honey can reduce oxidative stress and improve cognitive function. Animal experiments also show that certain antioxidants can reverse oxidative stress toxicity in rat models. However, synthetic antioxidants like BHA and BHT, when consumed in high doses, can be toxic and may even have anticarcinogenic effects. Epidemiological studies suggest that diets rich in antioxidants, such as fruits and vegetables, are associated with lower risks of chronic diseases like cancer and cardiovascular disease. However, individual supplementation trials have shown mixed results, with some studies indicating potential toxicity at high doses. This highlights the importance of consuming antioxidants in their natural food matrices, where they are more effective and safer. In conclusion, while exogenous antioxidants are beneficial at physiological doses, their high doses can be harmful. The safest and most effective way to obtain antioxidants is through a balanced diet rich in fruits, vegetables, and other natural sources. Supplementation should be approached with caution, as isolated high-dose antioxidants may have adverse effects. The complex interactions between antioxidants and other compounds in natural foods make them more effective and safer than isolated supplements.