The Role of Antioxidants in Disease Prevention

Free radicals are created when an atom or molecule gains or loses an electron, making it unstable. Free radicals are formed naturally in the body as a byproduct of turning food into energy or by coming in contact with something in the environment, like cigarette smoke, pollution, or UV rays. Free radicals can play an essential role in some normal cellular processes, but at high concentrations, they can be harmful and damage all the major components of our cells, including cell membranes, proteins, and DNA.

Antioxidants are chemicals that can neutralize free radicals and prevent them from causing damage. The body makes some natural antioxidants but relies on getting the rest from the diet. Examples of dietary antioxidants include lycopene, beta-carotene, and vitamins A, C, and E. Selenium is often thought to be an antioxidant, but its antioxidant effects are more likely to be due to the antioxidant activity of the proteins that contain selenium, not the selenium itself.

Eating a balanced diet is important to ensure you are getting a good mix of antioxidants as well as the vitamins, minerals, and nutrients your body needs to function optimally. Some foods high in antioxidants include many fruits and vegetables, like blueberries, blackberries, raspberries, strawberries, cranberries, sweet potatoes, carrots, red and green peppers, kale, spinach, and broccoli. Walnuts, pecans, and sunflower seeds also have high antioxidant content, as do red wine, pomegranate juice, tea, coffee, and dark chocolate.

The effects of antioxidants on heart health are unclear. Research into antioxidants' impact on cardiovascular diseases shows mixed results. For example, the Women's Health Study found that rates of major cardiovascular events were no different between women who took vitamin E and those who took placebo, but those who took vitamin E had a significant reduction in total cardiovascular death.

The research is mixed on whether antioxidants play a role in cancer prevention. In animal and laboratory studies, antioxidants have been shown to prevent damage from free radicals associated with cancer development, but many observational studies have yielded mixed results. There have also been nine randomized controlled trials of dietary antioxidant use for cancer prevention, but none of the results have provided adequate evidence that dietary antioxidant supplements are effective for this purpose.

Oxidative stress in the brain may contribute to a range of neurodegenerative disorders, and research shows antioxidants may be effective at treating some of them. Some of the most interesting results have been in treating Huntington's disease. Some natural compounds have had neuroprotective effects in Huntington's disease models, and vitamin C and alpha-lipoic acid have positively affected motor symptoms and survival rates in rodents. Clinical studies have also found that vitamin C and vitamin E supplements decreased the risk of cognitive decline in people over age 65, and a study in rats showed that vitamin C may be effective at preventing stress-related cognitive decline.

Research into whether antioxidants can be used in diabetes management is ongoing; so far, the results have been mixed. Increased dietary intake of beta-carotene for a ten year period has been associated with a reduced risk of diabetes, and increased vitamin C intake has been shown to lower the risk of this disease in Japanese women. But, a study of males taking beta-carotene showed it did not significantly reduce their diabetes risk. Human studies have found that there is a close association between insulin sensitivity and oxidative stress, but more conclusive research is needed on using antioxidants to treat type 2 diabetes.

The free radical theory of aging proposes that changes in the body occur due to free radical damage. Over time, this damage accumulates and causes us to age. Since this theory was introduced, it has evolved to emphasize the effect of free radicals on mitochondrial DNA and how various deletions and mutations accumulate and affect the body over time. It is unknown if antioxidants can slow the aging process, but the things you can do to limit your exposure to free radicals also benefit your health. It is a good idea not to smoke, limit alcohol intake, eat a healthy diet, and avoid direct sun exposure, whether or not you are concerned about antioxidants and free radicals.

There is no evidence to show that antioxidant supplements can positively affect cancer, cardiovascular disease, cataracts, or Alzheimer's risk. On the other hand, there is plenty of evidence that eating fruits and vegetables, foods that are rich in antioxidants and other beneficial nutrients, can lead to a lower risk of chronic diseases. For example, a 2017 review showed that people who eat more fruits and vegetables had lower risks of cancer and cardiovascular disease. It's also worth noting that there may be risks associated with high doses of antioxidant supplements. For example, high doses of beta-carotene can increase the risk of cardiovascular disease and lung cancer; high doses of vitamin E can affect blood clotting; and high doses of vitamin C can cause nausea, diarrhea, and stomach cramps and interfere with some cancer treatments.

Antioxidants can protect against some eye diseases. Research shows that although antioxidants like vitamin A, zeaxanthin, and lutein do not protect against age-related macular degeneration, others, like anthocyanins, carotenoids, and zinc, can. As for cataracts, clinical trials have failed to show that vitamin C supplementation can prevent cataracts, except in people who had low vitamin C levels to begin with. Unfortunately, many of these studies did not evaluate serum vitamin C levels, so more research is needed.

Antioxidants have been touted as a way to prevent everything from cancer to aging; unfortunately, there is little scientific evidence to back up many of these claims. One of the reasons it can be hard to determine the true effects of antioxidants is that many people get their antioxidants from healthy foods, like fruits and vegetables, and these foods also have many other beneficial substances in them. Plus, people who eat a lot of fruits and vegetables may be more likely to have a healthy lifestyle typically associated with eating these foods. There also seems to be a significant difference in how supplements act in the body compared to antioxidants consumed in foods. Supplements do not contain the same complex substances as fruits and vegetables, and high-dose supplements may behave differently in the body than the smaller doses in foods.

Many skin care products use antioxidants in their formulations, enabling you to apply antioxidants directly to the skin. Some of the benefits of topical antioxidants include protecting against UV rays and sun damage, calming inflammation, and smoothing the skin. Topical antioxidants have not been shown to have any effect on slowing chronological aging, but they can help the skin look younger by protecting against external factors like sun exposure, pollution, and smoking.

Researchers are experimenting with a range of different uses for antioxidants, including as coloring agents, preservatives, and additives in medication and as edible and renewable packaging. Some researchers are also looking into the antioxidant content of various foods to support as antioxidant-rich a diet as possible. They discovered that antioxidant content varied according to the growth, development, and harvest times of fruits and vegetables, indicating that there may be ways to enhance the natural antioxidants in the foods we already eat.

To ensure you get enough natural antioxidants, eat a well-rounded diet that includes a lot of fruits and vegetables. Specifically, foods that are high in antioxidants include apples, whole grains, carrots, tomatoes, spinach, pecans, walnuts, strawberries, dry beans, red beets, sesame, carob, seaweed, and herbs like sage, thyme, and oregano. Coffee, chocolate, and red wine also contain some antioxidants.

Antioxidants, often celebrated for their health-promoting properties, also possess a lesser-known, dualistic nature. While essential in combating harmful free radicals, they can, under certain conditions, contribute to oxidative stress. This paradox highlights the importance of a balanced approach to antioxidant intake. Primarily sourced from a varied diet, antioxidants in natural forms are typically more beneficial than high-dose supplements, which may inadvertently tip the balance towards harm. This delicate equilibrium underscores the complexity of antioxidants in disease prevention and overall health maintenance.