High-Dose Antioxidant Supplements: Why They Can Be Harmful or Have Mixed Effects
High-Dose Antioxidant Supplements: Why They Can Be Harmful or Have Mixed Effects 1. Introduction Antioxidants have long been celebrated as powerful protectors of human health. They neutralize free radicals — unstable molecules that can damage cells, contribute to inflammation , and accelerate the aging process. For decades, the narrative was straightforward: more antioxidants equal better health. This belief fueled a global market for antioxidant supplements, from vitamin C and vitamin E to selenium , beta-carotene , and exotic plant extracts . However, over the last 25 years, large-scale scientific studies have painted a far more nuanced — and sometimes troubling — picture. While adequate antioxidant intake is essential for good health, high-dose supplementation has not consistently delivered the promised benefits. In some cases, it has even increased disease risk or mortality. Understanding why requires a deeper look at how antioxidants work , the b...