The richest antioxidant foods are everyday fruits, vegetables, nuts, seeds, beans, tea and cocoa. Sweet peppers, citrus, kiwifruit, berries, leafy greens, sweet potatoes, almonds and sunflower seeds are standouts. Diets built on these foods are linked with better long-term health. High-dose antioxidant pills, however, have not delivered the same results in clinical trials.
Key Takeaways
- The main dietary antioxidants are vitamin C, vitamin E, carotenoids such as beta-carotene, and plant polyphenols such as flavonoids.
- Half a cup of raw red pepper has about 95 mg of vitamin C, more than an adult's daily need. An ounce of sunflower seeds or almonds has about 7 mg of vitamin E.
- "Superfood" is a marketing term. One review of 45 websites found 136 different foods given the label.
- People who eat more fruits and vegetables tend to have better health outcomes in large observational studies, but these studies cannot prove cause and effect.
- Large trials of high-dose beta-carotene and vitamin E pills found no benefit, and some found harm, especially in people who smoke.
- Getting antioxidants from a varied diet is safe. Talk to your clinician before taking high-dose antioxidant supplements.
Evidence grade: Moderate. Large observational reviews (95 studies in one 2017 meta-analysis) consistently link fruit and vegetable intake with better outcomes, but this cannot prove cause, and randomized trials of isolated antioxidant supplements in more than 290,000 people have not shown a benefit.
What Are Dietary Antioxidants?
Your cells make highly reactive, oxygen-containing molecules during normal activity. Some are called free radicals because they carry an unpaired electron. You are also exposed to them through cigarette smoke, air pollution and ultraviolet light from the sun. When the body makes more of these molecules than it can handle, the result is called oxidative stress, which can damage cells.
Antioxidants are substances that help limit that damage. Your body makes some of its own, and the National Center for Complementary and Integrative Health (NCCIH) notes that the body's own antioxidant enzymes are the most important part of this defense system. Others come from food. Vitamin E, for example, is a fat-soluble antioxidant that stops the chain of damage that starts when fats oxidize. Vitamin C helps regenerate vitamin E inside the body.
Researchers now know that more is not always better. NCCIH explains that large amounts of antioxidants may interfere with normal cell signaling and defense. Different antioxidants also work in different ways, so they are not interchangeable.
The Main Antioxidants in Food and Where to Find Them
The amounts below come from NIH fact sheets, which draw on USDA's FoodData Central database. You can look up any other food in FoodData Central.
| Antioxidant | Good food sources | Example amounts |
|---|---|---|
| Vitamin C | Sweet red and green peppers, oranges and orange juice, kiwifruit, broccoli, strawberries, Brussels sprouts, cantaloupe | Red pepper, raw, ½ cup: 95 mg. Orange, 1 medium: 70 mg. Kiwifruit, 1 medium: 64 mg. Adult RDA: 75–90 mg a day. |
| Vitamin E | Wheat germ oil, sunflower seeds, almonds, hazelnuts, peanut butter, sunflower and safflower oils, spinach | Sunflower seeds, 1 oz: 7.4 mg. Almonds, 1 oz: 6.8 mg. Spinach, boiled, ½ cup: 1.9 mg. Adult RDA: 15 mg a day. |
| Beta-carotene and other provitamin A carotenoids | Sweet potatoes, carrots, spinach and other leafy greens, cantaloupe, red peppers, mangos | Sweet potato, baked, 1 whole: 1,403 mcg RAE of vitamin A. Carrots, raw, ½ cup: 459 mcg RAE. |
| Polyphenols (including flavonoids and anthocyanins) | Grapes, apples, pears, cherries, berries, tea, coffee, cocoa and chocolate, cereals and dry legumes | These fruits contain up to 200–300 mg of polyphenols per 100 g. A cup of tea or coffee has about 100 mg. |
Lycopene, lutein and zeaxanthin are other carotenoids found in food. Unlike beta-carotene, the body does not turn them into vitamin A. Lutein and zeaxanthin are found in the eye.
Polyphenols are a very large family. More than 8,000 have been identified in plants, including over 4,000 flavonoids. Many give fruits and flowers their colors. Anthocyanins, the pigments in blue, purple and red produce, are one group of flavonoids. Foods usually contain a mix of many polyphenols, not just one.
A Closer Look at Popular Antioxidant Foods
- Berries: blueberries, raspberries and other berries are among the fruits richest in polyphenols. Strawberries also supply about 49 mg of vitamin C per half cup.
- Leafy greens: spinach and kale supply provitamin A carotenoids. Half a cup of boiled spinach also adds about 1.9 mg of vitamin E.
- Peppers, citrus and kiwifruit: these are the easiest way to cover your vitamin C needs. Steaming or microwaving vegetables, or eating them raw, helps keep more vitamin C than long cooking.
- Nuts and seeds: almonds, sunflower seeds and hazelnuts are among the best food sources of vitamin E.
- Orange vegetables: one baked sweet potato provides more vitamin A, as beta-carotene, than most adults need in a day.
- Beans, tea, coffee and dark chocolate: all contribute polyphenols to the diet, so they count toward your antioxidant intake even though they are rarely called superfoods.
Why "Superfood" Is a Marketing Term
A 2023 review by food scientists at the University of Santiago de Compostela looked at 45 English-language web pages about superfoods. The authors noted that the term is used frequently for marketing purposes. Between them, the pages called 136 different foods superfoods. The ten named most often were kale, spinach, salmon, blueberries, avocado, chia, walnuts, beans, fermented milks and garlic.
The reviewers found the information was usually not wrong, but it was very simplified. They warned that sites should avoid raising false expectations about health benefits. Their conclusion was that these foods can be good for you as part of a balanced diet.
Everyday foods such as sweet peppers, beans and tea are strong antioxidant sources even though they are rarely marketed as superfoods. Variety matters more than any single food. The same idea runs through our guide to diet and longevity.
What Research Shows: Antioxidant Foods vs Antioxidant Pills
Diets rich in fruits and vegetables
A 2017 meta-analysis in the International Journal of Epidemiology pooled 95 prospective studies. For every 200 g a day of fruits and vegetables, people had about a 10% lower risk of death from any cause during follow-up. Lower risks of cardiovascular disease and cancer were also observed. Lower risks were seen with intakes of up to about 800 g a day for most outcomes.
These were observational studies. They show a link, not proof that the foods caused the difference. NCCIH points out that people who eat more produce also tend to exercise more and get routine medical care. The benefit may also come from other substances in these foods, not only their antioxidants.
High-dose antioxidant supplement trials
When researchers tested isolated antioxidants as pills, the results were disappointing, and in some groups harmful:
- ATBC trial (1994): 29,133 male smokers in Finland took 50 mg of vitamin E, 20 mg of beta-carotene, both, or a placebo for five to eight years. Vitamin E did not lower lung cancer rates. Men given beta-carotene had 18% more lung cancer cases and 8% higher overall mortality than those who were not.
- CARET trial (1996): 18,314 smokers, former smokers and asbestos-exposed workers took 30 mg of beta-carotene plus 25,000 IU of vitamin A, or a placebo. The supplement group had a 28% higher risk of lung cancer and a 17% higher risk of death from any cause. The trial was stopped 21 months early.
- SELECT trial (2011 report): 35,533 men took 400 IU of vitamin E, selenium, both, or a placebo. With longer follow-up, the vitamin E group had a 17% higher rate of prostate cancer than the placebo group.
- Cochrane review (2012): 78 randomized trials with 296,707 participants found no evidence that antioxidant supplements lowered mortality. In the trials with the lowest risk of bias, beta-carotene and vitamin E slightly increased mortality. Vitamin C and selenium had no significant effect.
Based on this research, the U.S. Preventive Services Task Force recommended in 2022 against beta-carotene or vitamin E supplements for preventing cardiovascular disease or cancer, according to NCCIH. NCCIH notes one exception in its review: a specific combination of antioxidants and zinc studied in people already diagnosed with an age-related eye condition. That is a decision for an eye doctor, not a reason for general antioxidant use.
Why foods and pills behave differently
NCCIH offers several possible reasons. Antioxidants taken as purified chemicals may act differently from the complex mixtures in whole foods. Supplement doses are often much higher than the amounts in food. And the benefits of eating more produce may come from other parts of the food, or from the healthy habits of the people who eat it.
The research on antioxidants and aging follows the same pattern. Oxidative stress is one of the processes studied in aging, which is why antioxidants are often marketed for longevity, but the large supplement trials did not show that the pills help people live longer. For skin specifically, see antioxidants and skin aging.
How to Eat More Antioxidant-Rich Foods
- Breakfast: add berries to yogurt, oatmeal or a smoothie.
- Lunch: build a salad on spinach or kale with beans and sliced red pepper.
- Snacks: a small handful of almonds or sunflower seeds, or a kiwifruit or orange.
- Dinner: aim for two colors of vegetables, such as broccoli with sweet potato or carrots.
- Drinks: unsweetened tea or coffee adds polyphenols.
NIH notes that five varied servings of fruits and vegetables a day can provide more than 200 mg of vitamin C. Many of these foods are also good fiber sources, as covered in our article on high-fiber diets.
If you want a convenient addition on busy days, OPA All-in-One Greens provides a 2,500 mg organic greens blend, a 425 mg red fruit blend, 97 mg of vitamin C (113% of the Daily Value) and 4 g of fiber per scoop. It is meant to add to a varied diet, not replace whole fruits and vegetables. The diet studies above looked at whole foods, so their findings should not be assumed to apply to any powder or pill.
Safety and Interactions
Antioxidants from everyday foods are safe for most people. The concerns are mainly with high-dose supplements:
- Beta-carotene supplements: in the ATBC and CARET trials, high doses raised lung cancer risk in people who smoke or were exposed to asbestos. If you smoke or used to smoke, talk to your healthcare provider before taking beta-carotene supplements.
- Vitamin E: the upper limit for adults is 1,000 mg a day from supplements. High doses may raise the risk of bleeding. Talk to your doctor or pharmacist if you take anticoagulant or antiplatelet medicines, such as warfarin.
- Vitamin C: the upper limit for adults is 2,000 mg a day. High doses can cause diarrhea, nausea and stomach cramps. People with hemochromatosis should talk to their doctor first, because vitamin C increases iron absorption.
- Cancer treatment: antioxidant supplements may interact with chemotherapy and radiation. Talk to your oncology team before taking them.
- Cholesterol medicines: in one study, a combination of vitamins E and C, selenium and beta-carotene reduced the effect of two cholesterol-lowering drugs taken together. Talk to your doctor or pharmacist if you take cholesterol-lowering medicines.
If you are pregnant or breastfeeding, or are considering supplements for a child, check with a healthcare provider first.
Frequently Asked Questions
What are antioxidants?
Antioxidants are substances that help limit damage from free radicals, the reactive molecules your cells make during normal activity. Your body makes its own antioxidant enzymes. Others come from food, including vitamin C, vitamin E, carotenoids such as beta-carotene, and plant polyphenols such as flavonoids.
Which foods are highest in antioxidants?
For vitamin C, sweet red peppers, oranges, kiwifruit, broccoli and strawberries lead the list. For vitamin E, sunflower seeds, almonds and hazelnuts are top choices. Sweet potatoes and carrots are rich in beta-carotene. Berries, grapes, apples, cherries, tea and coffee supply polyphenols. A colorful mix covers all of them.
Are superfoods healthier than other foods?
Not as a category. "Superfood" is mainly a marketing term, and one review found websites applying it to 136 different foods. Many of those foods are nutritious, but no single food makes a diet healthy. Variety across fruits, vegetables, nuts, seeds and legumes matters more.
Should I take antioxidant supplements?
Most people do not need them. Large trials of high-dose beta-carotene and vitamin E found no benefit, and some found harm, especially in smokers. A 2012 review of 78 trials found no reduction in mortality. If you are considering a supplement, talk to your healthcare provider, especially if you smoke or take medicines.
Do antioxidants slow aging?
Oxidative stress is one of many processes studied in aging, which is why antioxidants are often linked to longevity. People who eat more fruits and vegetables tend to have better long-term outcomes in observational studies. However, randomized trials have not shown that antioxidant supplements help people live longer.
Can I get enough antioxidants from food alone?
Yes, for most people. Five varied servings of fruits and vegetables a day can provide more than 200 mg of vitamin C, well above the adult RDA of 75–90 mg. A daily handful of nuts or seeds helps you reach the 15 mg vitamin E target. See our guide to essential vitamins for immune function for more on daily needs.
Sources
- NIH Office of Dietary Supplements. Vitamin C: Fact Sheet for Health Professionals.
- NIH Office of Dietary Supplements. Vitamin E: Fact Sheet for Health Professionals.
- NIH Office of Dietary Supplements. Vitamin A and Carotenoids: Fact Sheet for Health Professionals.
- National Center for Complementary and Integrative Health. Antioxidant Supplements: What You Need To Know.
- U.S. Department of Agriculture, Agricultural Research Service. FoodData Central.
- Pandey KB, Rizvi SI. Plant polyphenols as dietary antioxidants in human health and disease. Oxid Med Cell Longev. 2009.
- Aune D, Giovannucci E, Boffetta P, et al. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality: a systematic review and dose-response meta-analysis of prospective studies. Int J Epidemiol. 2017.
- Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group. The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. N Engl J Med. 1994.
- Omenn GS, Goodman GE, Thornquist MD, et al. Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. N Engl J Med. 1996.
- Klein EA, Thompson IM Jr, Tangen CM, et al. Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2011.
- Bjelakovic G, Nikolova D, Gluud LL, et al. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Database Syst Rev. 2012.
- Cobos Á, Díaz O. 'Superfoods': reliability of the information for consumers available on the web. Foods. 2023.
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
Written and reviewed by Michael Gonzales, Founder, OPA Nutrition · Last reviewed: · How OPA researches and writes
