Oxidative stress is a term that many of us have heard or seen on food and vitamin labels for quite some time, but few people understand what this is.

Oxidative stress is the imbalance of reactive oxygen species (ROS), which is a byproduct of metabolism that is made up of different compounds, including forms of oxygen and hydrogen peroxide. The production of these potentially dangerous chemicals disrupts the normal state of cells. In some cases, ROS leads to damage to many compounds that make up our bodies, including proteins, fats and DNA. Studies have shown that ROS can play a role in many chronic illnesses, such as cancer, Parkinson’s disease, Alzheimer’s disease and heart disease.

However, ROS is a double-edged sword. While it plays a role in causing bodily harm, it also protects the body against germs. Superoxide, a type of oxygen-containing compound that is a component of ROS, helps the immune system kill bacteria and viruses that attack the body. The ability of the body to detoxify in this way or to repair damage prevents long-term harm to the body. Short-term ROS production can also help prevent aging.

You can help prevent oxidative stress, or reduce the damage that’s already been done, by eating foods that contain antioxidants—nutrients that balance harmful levels of ROS. Fruits and vegetables are naturally rich in antioxidants. There are also a lot of products that are marketed as antioxidant—including teas, juices, snacks and even vitamins—but natural sources are best. It is always best to consult your primary care provider to see what kind of antioxidant supplement you should try—if any—to avoid doing more harm than good.

Anberitha Matthews, PhD, is a vascular scientist and wellness coach at Redefining Health, LLC. She researches vascular injury as it pertains to oxidative stress to help clients improve their quality of life. In addition to being an APS member, she serves as vice chair for the Arteriosclerosis, Thrombosis and Vascular Biology Communications and Membership Council of the American Heart Association and performs consulting work in the areas of scientific editing, grantsmanship and protocol development.