Antioxidants are chemicals (both naturally occurring and man-made) that can prevent or slow cell damage. An “antioxidant” is actually not a substance; it’s a behavior. Any compound that can donate electrons and counteract free radicals has antioxidant properties.
Natural antioxidants are mainly found in fruits and vegetables, marine plants, and some seafood that eat marine plants. There are thousands of antioxidant compounds out there, but the most common dietary ones are vitamins A, C, and E, beta-carotene, and lycopene. Antioxidants can also be produced artificially and consumed in supplement form.
What Are Free Radicals?
Exposure to oxygen (aka oxidation) can “break” atoms, so they end up with unpaired electrons, which make them chemical loose cannons. These bad boys, called free radicals, are constantly on the hunt for spare electrons to stabilize their mixed-up atoms. Free radicals latch onto electrons from other cells, which can create a chain reaction of free radical-ness. Stealing nearby electrons means that the cell next door loses some of its electrons, therefore becoming a free radical in its own right. Sounds tiring.
Why Are Free Radicals a Bummer?
It’s rarely a good idea to mess with cell structure, and it can get gnarly when the cells undergoing oxidative stress contain DNA . Oxidative stress has been linked to serious diseases like cancer, heart disease, stroke, aging, diabetes, arthritis, fibromyalgia, Parkinson’s Disease, Alzheimer’s, autoimmune diseases, cognitive decline, and eye conditions like macular degeneration .
What Do Antioxidants Do?
If the human body were a baseball game, antioxidants would be the first baseman. Antioxidants are one of the first lines of defense that the body employs to keep free radicals in check and prevent them from causing a domino effect of damage on other cells. Antioxidant compounds can “donate” electrons to unstable free radicals so they don’t have to snatch electrons from unsuspecting nearby cells. Antioxidants can also help repair cell damage caused by free radicals.
What’s the Catch?
As is often the case with health buzzwords, antioxidants aren’t all they’re cracked up to be. There’s very little actual scientific proof that antioxidants are the magic bullet to protect us from heart disease, stroke, and cancer.
In fact, some studies have shown that consuming extra beta-carotene can actually increase risk of lung cancer in smokers. Several randomized trials have confirmed that cancer patients who took antioxidants supplements during their treatments actually had worse outcomes. In one randomized trial, women who took antioxidant supplements had higher rates of skin cancer than those who didn’t.
Studies involving heart disease and strokes show that antioxidants (even when used in various combinations) have a largely placebo effect (the only exception is vitamin E, which significantly benefited women with cardiovascular disease)  .
Also, recent research has disproven the idea that all free radicals are inherently bad for health. The body actually requires a certain amount of these infamous compounds to kill cancer cells and bacteria, among other tasks. Overloading on antioxidant supplements can disrupt these beneficial free radical behaviors, leading to disease or illness.
While we don’t know exactly how dietary antioxidants affect disease, a healthy diet with plenty of antioxidant-rich fruits, vegetables, and grains is always beneficial.