Free radicals are unstable molecules that can damage the DNA inside cells if they build up. They may play a role in a range of diseases and the visible signs of aging.
Antioxidants are another type of molecule that helps remove free radicals. Plants, such as fruits, vegetables, and herbs, are key sources of antioxidants.
Keep reading to learn more about free radicals and their role in human health.
Understanding free radicals requires a basic knowledge of chemistry.
Atoms are surrounded by electrons that orbit the atom in layers called shells. Each shell needs to be filled by a set number of electrons. When a shell is full, electrons begin filling the next shell.
If an atom’s outer shell is not full, it may bond with another atom, using the electrons to complete its outer shell. These types of atoms are known as free radicals.
Atoms with a full outer shell are stable, but free radicals are unstable, and in an effort to make up the number of electrons in their outer shell, they react quickly with other substances.
When oxygen molecules split into single atoms that have unpaired electrons, they become unstable free radicals that seek other atoms or molecules to bond to.
Free radicals are a
Scientists believe that free radicals can damage cells, including their DNA, over time. This affects how cells work and how they replicate, potentially leading to a range of health problems.
According to a 2022 review, various studies have connected oxidative stress due to free radicals to:
- neurodegenerative diseases, such as Alzheimer’s and other dementias
- cardiovascular disease
- respiratory diseases
- digestive diseases
- cancer
There is also a theory that free radical buildup explains the aging process, known as the “free radical theory of aging.”
Proponents argue that as the body ages, it accumulates free radicals. This results in more oxidative stress and more damage to cells, or their mitochondria, which contributes to aging.
The theory offers one explanation for why even healthy bodies age and deteriorate over time and why some people age more slowly than others. However, scientists are still unsure how exactly this process works.
Although the body naturally produces free radicals, environmental factors can accelerate their production. According to a 2019 review of past research, these include:
- smoking
- a nonnutritious diet
- air pollution from fossil fuels
- exposure to toxic chemicals
- radiation exposure, which includes radiation from the sun or UV light
Antioxidants are substances that lessen or prevent the effects of free radicals. They donate an electron to free radicals, thereby reducing their reactivity.
What makes antioxidants unique is that they can donate an electron without becoming reactive free radicals themselves.
However, no single antioxidant can combat the effects of every free radical. Just as free radicals have different effects in different areas of the body, every antioxidant behaves differently due to its chemical properties.
It is also important to remember that any substance can become harmful in the right quantity. In some contexts, antioxidants may become pro-oxidants, particularly at high doses.
This means the antioxidant grabs electrons from other molecules, creating chemical instability that can cause oxidative stress.
A 2022 review states that getting antioxidants from food may be the best way to avoid consuming too much of them.
Thousands of chemicals can act as antioxidants. Vitamin C, vitamin E, glutathione, beta-carotene, polyphenols, and plant estrogens known as phytoestrogens are among the many antioxidants that may scavenge free radicals.
Many foods are rich in these antioxidants, including:
Brightly colored fruits and vegetables often contain antioxidants. By “eating the rainbow,” people can get a variety of antioxidants in their diet.
The antioxidant theory of aging has led some companies to push the sale of antioxidant supplements. However, research on whether these are necessary or beneficial has been mixed.
In some cases, specific antioxidants show promise as complementary therapies for specific conditions. For example, a
However, research on other conditions is more complex. For example, a 2020 review states that while animal studies have found evidence that antioxidant supplements may help with cardiovascular disease, human trials have had mixed outcomes.
Antioxidants may even be harmful in some cases. For example, a 2019 study found that people who took beta-carotene supplements and who smoked had higher rates of lung cancer.
The authors of a 2022 review note that there is a need for more research on whether antioxidant supplements can be beneficial as a treatment for diseases.
At present, it may be best for most people to get their antioxidants from a varied diet.
Free radicals are unstable molecules that can damage cells and their DNA. Research suggests that they may play a role in many diseases, such as dementia, cardiovascular disease, and cancer.
Scientists also theorize that free radicals may explain the aging process. However, there are still many factors scientists do not know about free radicals and their role in health.
Certain factors may speed up the formation of free radicals, such as aging, pollution, exposure to radiation, and smoking.
Antioxidants are substances that can reduce or prevent free radical damage. People can usually get antioxidants from their diet. Eating a variety of colorful fruits, vegetables, and other plant foods may help people eat more antioxidants.
