Decades of nutrition studies suggest that people who eat more fruits and vegetables live longer and have a lower risk of heart disease, cancer, stroke, cognitive decline, and eye disease associated with aging. At least part of that benefit comes from antioxidants, researchers suggest, substances that fight inflammation by reducing free radicals and oxidative stress. If antioxidant foods help you live a longer and healthier life, then high-dose supplements must be even better, right? Not so fast.
Antioxidant supplements are purported to help you live a longer and healthier life because they fight free radicals and reduce oxidative stress. That sounds good, but what does it really mean?
When you eat, exercise, sit in the sun, or breathe polluted air, your body creates byproduct molecules called free radicals. These molecules have an uneven number of electrons, which makes them unstable. Your body can usually manage free radicals by finding an extra electron to neutralize them. Ideally, these electrons come from antioxidants—substances found in fruits and vegetables that can safely donate extra electrons—such as vitamins C and E, plant pigments beta-carotene and lycopene, the minerals zinc and selenium, and organic phenolic compounds.
If your body can’t access enough antioxidants to stabilize the free radicals it creates, however, you can start to suffer cell damage and inflammation, called oxidative stress.
While clinical trials show that antioxidant-rich foods are beneficial, the science is less compelling when it comes to supplements.
In June 2022, a review article in the American Medical Association’s journal JAMA reported that there is insufficient evidence to show that antioxidant supplements have any benefit for heart disease, cancer, or longer life. Furthermore, beta carotene supplements can increase the risk of lung cancer in smokers, and vitamin E in large doses may increase the risk of bleeding into the brain.
The most likely reason that antioxidant supplements have failed is that the benefits of antioxidants come from a balance of several antioxidants with helper molecules and other nutrients in foods. It is not as simple as pulling out one antioxidant and bombarding the body with high doses. That would be like taking one instrument out of an orchestra, playing it loudly, and expecting to hear a symphony.
Another possibility is that even antioxidants in foods are not as beneficial as researchers have assumed. The nutrition studies these assumptions have been based on were observational, meaning that the researchers looked back at many diet survey questions and then compared diets and health outcomes over time. Just because people who ate more fruits and vegetables were healthier doesn’t mean the diets were the cause. People who ate lots of fruits and vegetables may have also had other healthy behaviors, like not smoking, getting a lot of exercise, or avoiding junk food, that could influence health.
The evidence linking free radicals to cancer, heart disease, cognitive decline, and vision loss is strong, so getting antioxidants from a healthy diet makes sense. There are plenty of delicious options:
You can also avoid outside sources of free radicals by not smoking or getting a sunburn.
