“Antioxidants” is one of those buzzwords that gets thrown around a lot. We know that foods full of these seemingly magical compounds are good for us—but what are antioxidants exactly? What do they actually do in our bodies? And why is everyone always singing their praises? Here’s what you need to know about the science behind what antioxidants can do for us.
What antioxidants are and what they actually do
Before we talk about antioxidants, we gotta talk about free radicals—another nebulous buzzword. “Free radicals is a general term used for compounds that are highly reactive, which means that they can attach and bind to and ultimately damage normal [cells] in the body, such as DNA,” Edward Giovannucci, M.D., professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health, tells SELF.
Some free radicals are okay—these unstable molecules are actually naturally formed when we exercise and metabolize food, Dr. Giovannucci says. We can also be exposed to sources of free radicals in the environment, like cigarette smoke, sunlight, and air pollution, according to the National Center for Complementary and Integrative Health (NCCIH), a branch of the National Institutes of Health. Other environmental toxins that can cause high levels of free radicals are ionizing radiation and some metals, according to the National Cancer Institute (NCI).
But high concentrations of free radicals in the body can lead to oxidative stress, a process that can cause damage to your cells. That oxidative stress is believed to be a factor in the development of a number of conditions such as cancer, heart disease, Type 2 diabetes, Alzheimer’s disease, Parkinson’s disease, cataracts, and aging-related macular degeneration, according to the NCCIH.
That’s where antioxidants come in. Known as free radical scavengers, according to the NCI, antioxidants effectively neutralize the free radicals that cause this oxidative stress (the anti in antioxidant). While we make some of our own antioxidants, our bodies count on our diets to get enough of them. “Antioxidants are compounds found in food that stop or delay damage to the cells,” Lauri Wright, Ph.D., R.D., L.D., assistant professor of nutrition at the University of South Florida, tells SELF.
Plant foods like fruits and vegetables are especially rich sources of these free-radical-crushing compounds, which include vitamin A, vitamin C, vitamin E, the mineral selenium, lutein, and lycopene, Wright says. “Antioxidants are released from the foods we eat through digestion and travel through the bloodstream and into cells,” where they do work on free radicals, Wright explains.
What we don’t know about antioxidants
It’s really hard to tell how important each individual antioxidant compound is in the human body. For one thing, there are just so many. As Dr. Giovannucci points out, there are many other lesser-known compounds in foods that, at least in laboratory settings, have been shown to have antioxidant properties. We’re talking thousands of antioxidative compounds, potentially. So it’s very possible that different antioxidants contained in, say, a tomato, are working together. “There are so many compounds that many interactions are possible,” Dr. Giovannucci says. Not to mention the many other vitamins, minerals, and phytochemicals present in plants!
Making things more complicated is the fact that it’s tricky to figure out how exactly these compounds act in the human body. Lab experiments demonstrate that antioxidants can counteract oxidative stress in cells and animals by stabilizing free radicals and preventing cell damage associated with developing cancer, the NCI explains. But a laboratory test can’t tell us how something acts once it’s in our digestive system and bloodstream. “In the body it has to first be absorbed in the intestine, then get to the appropriate organ in high enough concentrations, and then get to the precise part of the cell that experiences free radical damage,” Dr. Giovannucci explains. This all makes it pretty hard to pinpoint the role of any one antioxidant in our health.