Antioxidant vitamins don’t stress us like plants do—and don’t have their beneficial effect.     Illustration by John Hendrix .  Perhaps you steer toward “superfoods , ” fruits ,  nuts ,  and vegetables advertised as “antioxidant , ” which combat the nasty effects of oxidation in our bodies .    Maybe you take vitamins to protect against “free radicals , ” destructive molecules that arise normally as our cells burn fuel for energy ,  but which may damage DNA and contribute to cancer ,  dementia ,  and the gradual meltdown we call aging .   Warding off the diseases of aging is certainly a worthwhile pursuit .    But evidence has mounted to suggest that antioxidant vitamin supplements ,  long assumed to improve health ,  are ineffectual .    Fruits and vegetables are indeed healthful but not necessarily because they shield you from oxidative stress .   Eating food from plants that have struggled to survive toughens us up as well .    Rather than killing us ,  t...