Anti-cancer, anti-aging, anti-dementia — with health claims like these, it’s no wonder people are looking for ways to increase antioxidant intake from the foods they eat to their skin care routines.
But what exactly are antioxidants? And what can we do to harness the power of these mighty compounds?
[See: Supplements for Athletes.]
What Are Antioxidants?
“Antioxidant” is basically an umbrella term that encompasses different substances that help maintain cell health and neutralize or limit damage caused by free radicals, which are compounds that attack healthy cells and can lead to DNA damage.
Your body naturally produces free radicals in response to everyday activities such as breathing, turning food into energy or physical activity. However, free radicals are also a byproduct of lifestyle habits — like smoking, alcohol use and poor dietary habits — and environmental factors, such as pollution, pesticides and sun exposure. When there are too many free radicals and not enough antioxidants to counterbalance them in the body, a phenomenon called oxidative stress may occur and lead to tissue and cell damage.
“Free radicals are implicated in cancer and a number of conditions, including heart disease,” says Dr. Donald Hensrud, an associate professor of nutrition and preventive medicine at Mayo Clinic and editor of The Mayo Clinic Diet.
[READ: Fighting Inflammation With Glutathione Antioxidant Supplements and Injections]
Common Antioxidants
There are hundreds of antioxidants that have been identified by scientists so far. Some of the best-known and most-studied types are:
— Anthocyanins. These pigments produce blue, purple and red colors in fruits and veggies like berries, grapes, cranberries, eggplant, beets and red cabbage, as well as in red wine. Anthocyanins fall under the bioflavonoid category of antioxidants.
— Carotenoids. These pigments produce bright orange, red and yellows in fruits and vegetables like carrots, oranges, grapefruit, squash and yams. Carotenoids such as lutein and beta-carotene are also found in leafy greens like spinach. Lycopene, another type of carotenoid, gives tomatoes their bright red color. Carotenoids are essential for eye health, among other functions.
— Terpenoids. These antioxidants are found in foods like garlic, onions, cauliflower, coconuts and whole grains. They help counter disease-causing organisms like fungi, parasites and viruses.
— Vitamin C. Water-soluble vitamin C is found in a wide range of citrus and other fruits like berries and kiwi, and in vegetables like bell peppers and Brussels sprouts. Vitamin C has multiple functions and is vital for bone, muscle, cartilage and blood vessel development.
— Vitamin E. Falling under the category of tocopherols or tocotrienols depending on its form, vitamin E is found in leafy green vegetables, seeds, nuts and vegetable oils.
— Zinc. The mineral zinc is found in the largest amounts in meat, fish and seafood. Oysters contain the most zinc of any food. Eggs and dairy contain zinc, as well. Breakfast cereals and other foods like flour are sometimes fortified with zinc. Wound healing and blood clotting are among zinc’s important functions.
As you can see, some vitamins and minerals also play an antioxidant role in the body, which can be confusing. Antioxidants are compounds that prevent or diffuse the damaging effects of free radicals. Vitamins A, C, and E can react with certain free radicals and prevent them from harming your cells. Minerals, such as zinc, form the active sites of antioxidant enzymes in the body — and these enzymes can remove free radicals before they can cause damage.
“Vitamins and minerals are often considered superior antioxidants because they can work in tandem with the body’s defense systems and can often be restored after they act to protect cells, unlike compounds from plants, which are lost,” says Alexander Michels, research associate with the Linus Pauling Institute at Oregon State University in Corvallis, Oregon.
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Eat the Rainbow
Your body naturally produces some antioxidants to counteract the effects of free radicals, but the foods you eat play a big role in giving your body the ammunition it needs to counteract potential damage. Diet and nutrition experts frequently encourage eating a “rainbow” of colorful foods for optimal health — and no, they don’t mean M&Ms or Skittles.
“Many of the antioxidants themselves are the plant pigments that make them such bright colors,” says Dr. Michael Greger, founder of NutritionFacts.org and a member of the U.S. News Best Diets expert panel. “The same biochemical property that gives them those beautiful colors is actually the same property that allows them to detox free radicals.”
You can see for yourself which foods are richest in pigment, Greger says, like the difference between white and sweet potatoes. Red cabbage has more pigment than regular cabbage, red onions have more than white onions, purple grapes are better than green grapes and so forth. Even black sesame seeds are richer in antioxidants compared to the regular version, he says.
However, pigmentation alone is only part of the picture, at least when it comes to certain vegetables, like cauliflower and potatoes. Several studies and reviews support the rich antioxidant benefits of white potatoes. White potatoes exceed sweet potatoes in total antioxidant content and contribute a significant portion of specific antioxidants in the flavonoid, phenolic acid and carotenoid types, evidence shows.
There is much we do not know yet about how the various properties in foods work together. Different antioxidants have unique properties and chemical makeup meaning they play different roles and have different health benefits. For example, eating or taking a supplement with a high level of vitamin C and calling it a day will not have the health benefits that eating a wide variety of foods of various colors and nutritional content that includes vitamin C will.
In a way, antioxidants function together as a team — so focusing on a single or a few antioxidants alone may be counterproductive. They also work with other properties in food like phytochemicals, which are various biologically active compounds found in plants.
“Antioxidants work in concert,” Greger says. “Supplements might have a few antioxidants, whereas our bodies rely on hundreds of them — all working together to create this network to help our bodies dispose of free radicals. And high doses of a single antioxidant can upset this delicate balance. So, the whole food may be greater than the sum of its parts, creating a kind of synergistic reaction. That’s why we should try to get our antioxidants the way nature intended — and that’s from real food.”
Focusing on a balanced diet makes sense.
“In the past, we used a reductionist approach to nutrition: ‘What’s the one nutrient that’s beneficial or one food that’s beneficial?'” Hensrud says. “As in: ‘Blueberries are the best source of antioxidants so how many blueberries should I eat?'”
Instead, he prefers to talk to his patients in practical, pragmatic terms.
“The bulk of the evidence supports a diet of minimally processed foods and mostly plants,” Hensrud says. “It sounds deceptively simple, but that’s what’s most important.”
Here are examples of foods with relatively high antioxidant content (measured by millimoles per 100 grams):
— Artichoke (boiled): 4.5.
— Blueberries: 9.
— Black chokeberries: 13.5.
— Chocolate (for baking, unsweetened): 10.
— Clove (dried, ground): 126.
— Coffee beans (roasted, black): 23.
— Oregano (dried): 96.
— Pecans (with skin): 10.5.
— Pomegranate (yellow pith only): 56.
— Saffron (dried, ground): 62.
— Walnuts (with skin): 16.
The big takeaway: Plant foods have 64 times more antioxidants than animal foods, on average, according to Greger. In particular, berries have about 10 times as much as other fruits and vegetables and are only beaten out by herbs and spices in their antioxidant proportions.
Antioxidants’ Benefits
Being mindful of your antioxidant intake is a great way of maintaining your overall health and promoting your longevity. A review study published in the journal Advances in Nutrition evaluated results from 41 studies involving more than 500,000 total participants. In 74,000 cases, they found an inverse association between death risk and overall dietary antioxidants or certain specific antioxidants, including carotenoids and vitamin C. This suggests a reduced risk in all-cause mortality with greater antioxidant intake.
Antioxidants may also play a role in reducing the risk of heart disease, cancer and age-related conditions like dementia and macular degeneration, according to a large body of research.
— Brain benefits: Antioxidants may help counter the damaging effects of oxidative stress on the brain. Research suggests that consuming antioxidants from food or supplements can help mitigate oxidative DNA damage by reducing the buildup of reactive oxygen species, which are free radicals that can lead to damage to DNA, RNA and proteins, as well as cell death. By protecting the brain from oxidative stress, antioxidants can help shield against neurodegenerative conditions, such as cognitive decline.
— Cancer prevention: Antioxidants appear to play a role in preventing certain cancers. A European study found that the risk of breast cancer was about 27% to 34% lower among women who consumed the highest levels of dietary vitamin C and some types of carotenoids, compared with women who consumed the least of these antioxidants.
— Heart health: Fruits and vegetables loaded with antioxidants may prevent cardiovascular disease. A roughly decade-long study of about 5,100 participants ages 30 and older assessed their dietary intake to estimate the development of cardiovascular disease associated with total intakes of vitamins A, C and E and zinc. Fruits, vegetables and legumes were the main antioxidant sources. The study’s results suggest that vitamin E intake may lower the risk of cardiovascular disease.
— Reduce dementia risk: Adding high-antioxidant foods to your diet now could help prevent dementia later, thanks to three key antioxidants: lutein, zeaxanthin and beta-cryptoxanthin.
— Skin protection: Dermatologists are increasingly recommending products such as serums and moisturizers with certain antioxidants like vitamin C, vitamin E and niacinamide to help protect and keep the skin barrier healthy allowing it to better defend against harmful UV light, chemicals and pollution. On a molecular level, they help neutralize the free radicals that are detrimental and are thought to play a role in skin aging and skin cancer.
Teasing out antioxidants’ prevention power is challenging in one way.
“Total antioxidant capacity in a diet correlates with lower risk of getting cancer, lower risk of dying from cancer and lower risk of dying prematurely altogether,” Greger says. “The problem, of course, is that high-antioxidant foods are among the healthiest foods, so there are all sorts of wonderful things found in these foods. How do we really know it’s the antioxidants?”
The bottom line is: If you focus on diverse, healthy, plant-based foods, you’ll reap benefits from antioxidants along with other key substances.
“There is not enough scientific evidence to suggest one group of phytochemicals-antioxidants versus another, so it would be best to work on the foods with dense amounts of phytochemicals-antioxidants in general. Focusing on the darkest colors of fruits and vegetables (greens, reds, and purples, for example) is a good way to get more of the compounds that are beneficial,” Michels says.
Antioxidant Supplements
Antioxidant supplements may be ineffective and, in some cases, harmful.
“Antioxidant supplements are a multibillion-dollar industry, touted for anti-aging properties, but we have hundreds of studies to the contrary,” Greger says.
However, an antioxidant ‘cocktail’ has been found beneficial for some patients with age-related macular degeneration, a progressive eye disease.
Building on our knowledge of healthy antioxidant properties in food, there was a wave of studies on antioxidant supplements. One study conducted in part by the National Cancer Institute followed 30,000 male smokers in Finland to determine whether specific supplements prevented lung and other cancers. No prevention benefit was seen from either supplement, and there may have even been unintended negative effects of supplementation.
“Unexpectedly, we observed a higher incidence of lung cancer among the men who received beta-carotene than those who did not,” researchers reported.
A different study published in JAMA followed nearly 40,000 healthy women to determine if vitamin E supplementation decreases risk of cardiovascular disease and cancer. Researchers found no overall preventive benefit for major cardiovascular events including heart attacks, stroke or cardiovascular death, no overall cancer benefit or effect on total mortality in women taking vitamin E. The data did not support vitamin E supplementation for preventing cardiovascular disease or cancer among healthy women.
Many antioxidant supplementation studies have not shown to confer health benefits, which may be because many antioxidants work best in tandem with other nutrients, plant chemicals (polyphenols) and even other antioxidants. Also, there are differences in types and amounts of antioxidants found in food versus supplements. For example, vitamin E supplements typically come in one form, alpha-tocopherol, whereas in food there are eight different forms of it.
When considering a supplement, keep in mind the supplement industry is not regulated by the Food and Drug Administration. Therefore, ingredients may not be as advertised, and the suggested dose may be too high to be healthy or too low to be effective. Speak to your doctor to find out if a particular supplement and dosage may be right for you.
Pro-Oxidant Foods
On the flip side of antioxidants, certain foods are higher in harmful substances — known as pro-oxidants — that can actually contribute to unhealthy oxidative stress. While they may confer some health benefits, it’s important to counterbalance them with antioxidant-rich foods.
Try to be aware of your consumption and limit these pro-oxidant foods:
— Sugar. Soda, candy and many desserts are often high in sugar.
— Refined carbohydrates. White flour, rice and bread are refined carb examples.
— Processed meats. Animal protein and high-fat content may contribute to inflammation and pro-oxidation.
“Sugar is a pro-oxidant,” Greger says. “Drink a soda and you’re going to decrease the total antioxidant content of your bloodstream. However, interestingly, if you drink the same amount of sugar in the form of orange juice, you don’t get the spike on oxidation. Why? Because the sugar in food is part of a package deal, with antioxidants like vitamin C — just like nature intended.”
So, rather than spooning sugar in your coffee or eating frosting-rich cake, satisfy your sweet tooth with some fruit.
Similarly, a fat source like heavy whipping cream is highly oxidative. However, healthy fatty high-fat foods, like nuts, avocados or extra-virgin olive oil don’t produce the same effect because they come “prepackaged” with antioxidants.
If you have a meal like a bagel with cream cheese, adding strawberries for dessert can neutralize free radical damage.
“Otherwise, by lunchtime, you’re already in oxidative debt,” Greger says. “You’ve used up antioxidants and dug your hole deeper.”
Ultimately, it’s important to stay mindful of what you eat.
“Every meal … is an opportunity to tip the balance from a pro-oxidant to an antioxidant direction,” Greger says.
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Antioxidants: What Are They and Why Do We Need Them? originally appeared on usnews.com
Update 07/13/23: This story was previously published at an earlier date and has been updated with new information.
