Final answer:
Antioxidants like vitamin C, vitamin E, and β-carotene are substances that mitigate the damaging effects of free radicals on normal physiological functions by neutralizing them.
Step-by-step explanation:
Substances like vitamin C that significantly decrease the adverse effects of free radicals on normal physiological functions are known as antioxidants. These substances, including vitamin E and β-carotene, protect the body by neutralizing free radicals, which are unstable molecules with unpaired electrons created through metabolic reactions and environmental factors such as pollution and radiation. Antioxidants act by donating an electron or hydrogen atom to the free radicals, stopping the chain reactions they cause, and thereby reducing damage to cells and tissues.
Vitamin C, for example, acts as a radical scavenger in the blood, while vitamin E protects fatty substances by becoming a less reactive radical itself, which can be excreted safely from the body. Additionally, β-carotene functions as a provitamin, being able to convert into vitamin A in the body and aiding in the fight against free radical damage.