Final answer:
Selenium is the mineral that serves as a cofactor in enzymes like glutathione peroxidase, which neutralize free radicals in the body, thereby preventing cellular damage from oxidative stress.
Step-by-step explanation:
The mineral that serves as a cofactor in chemical reactions that neutralize free radicals in the body is selenium. Selenium is essential for the activity of antioxidant enzymes like glutathione peroxidase, with only trace amounts required. It functions alongside vitamins such as vitamin C and vitamin E, and provitamin ß-carotene, which also act as antioxidants to prevent damage from free radicals. Free radicals are highly reactive molecules with unpaired electrons and can be generated through metabolic reactions or environmental factors like radiation and pollution. Antioxidants like selenium help to neutralize these free radicals by participating in reactions that reduce their reactivity, thus protecting cells from oxidative stress and DNA damage.