What Are Free Radicals and Why Are They Bad?

Medically Reviewed on 10/19/2021
what are free radicals and why are they bad
Free radicals are unstable atoms that can damage cells, cause diseases, and accelerate aging. Learn which foods can help fight free radical damage

Free radicals are unstable atoms that are naturally formed during metabolism or by exposure to environmental toxins. In excess, free radicals can damage cells, cause diseases, and accelerate aging.

While the body produces free radicals every day, its defense system is capable of eliminating the excess. However, when there is a disturbance in maintaining this balance, excess free radicals stay in the body and cause oxidative stress.

Multiple studies have shown that oxidative stress can lead to a range of diseases, including:

Other studies have linked the formation of free radicals to the acceleration of aging, such as wrinkles, metabolic disorders (such as diabetes mellitus), and damage to blood vessel lining.

What causes free radical formation?

Free radicals are produced naturally in the body every day. However, certain factors can increase their production:

  • Exposure to toxins such as pesticides, dyes, irritants, and air pollution
  • Smoking
  • Alcohol
  • Foods high in saturated fats
  • Stress

What are antioxidants?

Antioxidants fight the damage caused by free radicals and minimize the effects of oxidative stress on your body. These defenders can be obtained from food and play a role in repairing DNA and maintaining the health of cells.

Some common antioxidants and their food sources include:

  • Vitamin C
    • Broccoli
    • Brussels sprouts
    • Cantaloupe
    • Cauliflower
    • Grapefruit
    • Leafy greens (turnip, mustard, beets, collards)
    • Honeydew
    • Kale
    • Kiwi
    • Lemon
    • Orange
    • Papaya
    • Strawberries
    • Tomatoes
    • Bell peppers
  • Vitamin E
    • Almonds
    • Avocado
    • Swiss chard
    • Leafy greens
    • Peanuts
    • Red peppers
    • Spinach (boiled)
    • Sunflower seeds
  • Carotenoids, such as beta-carotene and lycopene
    • Apricots
    • Asparagus
    • Beets
    • Broccoli
    • Cantaloupe
    • Carrots
    • Bell peppers
    • Kale
    • Mangos
    • Turnip
    • Collard greens
    • Oranges
    • Peaches
    • Pink grapefruit
    • Pumpkin
    • Winter squash
    • Spinach
    • Sweet potato
    • Tomatoes
    • Watermelon
  • Selenium
    • Brazil nuts
    • Fish
    • Shellfish
    • Beef
    • Poultry
    • Barley
    • Brown rice
  • Manganese
    • Shellfish
    • Whole grains
    • Nuts
    • Soybeans
    • Leafy greens
  • Zinc
    • Beef
    • Poultry
    • Oysters
    • Shrimp
    • Sesame seeds
    • Pumpkin seeds
    • Chickpeas
    • Lentils
    • Cashews
    • Fortified cereals
  • Quercetin
    • Apples
    • Red wine
    • Onions
  • Catechins
    • Tea
    • Cocoa
    • Berries
  • Resveratrol
    • Red and white wine
    • Grapes
    • Peanuts
    • Berries
  • Coumaric acid
    • Spices
    • Berries
  • Anthocyanins
    • Blueberries
    • Strawberries


What percentage of the human body is water? See Answer

Health Solutions From Our Sponsors

Medically Reviewed on 10/19/2021
Mayo Clinic. Slide show: Add antioxidants to your diet. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/multimedia/antioxidants/sls-20076428

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. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/