Free radicals are created naturally in the body during your day-to-day, like when you metabolize food, but they're also generated by external sources. Some examples of external sources of free radicals include: 

• Alcohol 
• Cigarettes 
• Air pollution 
• Processed meats

Free radicals damage the body because they attach to healthy cells, which disrupts the cell's usual life-sustaining functions. 

The reason free radicals attach to cells in the first place is because free radicals are a particular type of atom, called an unstable atom. 

Atoms create up just about everything, from your skin cells to the food you eat. And those atoms are surrounded by electrons. 

Now, when an atom has enough electrons, it's called a stable atom, and when it's missing some electrons, it's unstable. Here's the important part: Unstable atoms want to become stable.

When free radicals attack important molecules in the cell such as DNA, proteins, carbohydrates, and fats, it leads to large-scale cell damage and subsequent disease

The good news is our body has an defense system called the antioxidant defense system to protect us from free radicals. 

An antioxidant is any stable compound able to give up an electron of their own to neutralize, or "turn off" free radicals. They are found in fruits, vegetables, and other plant-based, whole foods. Several vitamins, such as vitamins E and C, are effective antioxidants.