Antioxidants help rid your body of waste substances called free radicals. These free radicals are unstable molecules that the body produces as it processes food and in reaction to environmental pressure. Free radicals damage the body by producing inflammation that can lead to disease, particularly illnesses such as arthritis, heart disease, cancer, and others. 

To help you visualize how antioxidants work, think of free radicals as microscopic monsters circulating throughout the body. Antioxidants are the monster hunters that zero in on free radicals and neutralize them. This process helps protect the body from disease. 

Most plant based foods — fruits and vegetables — are rich in antioxidants; these include berries, citrus fruits, pineapple, pomegranate, green leafy vegetables, carrots, beets, and green tea. 

There are variations of antioxidants in different foods and each has a different role in relation to the organ or body system where they work to clean up free radicals. Some of the many antioxidants that support immunity are: 

Green tea: provides catechins and epigallocatechin gallate (EGCG). 
Bioflavonoids and Vitamin C: found in citrus fruits. 
Selenium: a trace mineral (meaning we only need small amounts of it on a daily basis) found in Brazil nuts. 

Before taking antioxidants in pill form, consult with a holistic physician who can determine which types and sources (food sources are best) are most important to your personal health for preventing or helping to heal illness.

Resources:

Lobo V, Patil A, Phatak A, Chandra N. “Free radicals, antioxidants and functional foods: Impact on human health”. Pharmacogn Rev. (2010) 4(8):118-126. doi:10.4103/0973-7847.70902 

Hourieh Alkadi. “A review of free radicals and antioxidants.” Infect Disord Drug Targets (2020) 20(1):16-26. doi: 10.2174/1871526518666180628124323.