Antioxidant Rich Foods: What the Rankings Actually Measure

The most concentrated antioxidant compounds in an ordinary diet sit in herbs and spices, berries, cocoa, tea, coffee and olive oil. That much is consistent across every ranking I've looked at. What isn't consistent is what those rankings mean.

I know that's a letdown, because the list you've seen online is probably scored on a laboratory test the USDA itself stopped publishing in 2012. Those scores describe how a food extract behaves in a tube. They don't describe what happens after you eat a berry.

The foods that carry them, by category

Polyphenols are the largest group of antioxidant compounds in food, and blueberries, cocoa, tea, coffee and olive oil are the ones people think of first. "Antioxidant" is the broader word, though. It also covers vitamin C, vitamin E, the carotenoids and selenium, which turn up across ordinary fruit and vegetables.

The compounds differ by food, and that matters more than any total. Cocoa carries flavanols. Green tea carries catechins. Coffee carries chlorogenic acids, which roasting reduces, so a lighter roast keeps more of them. Walnuts and pecans carry ellagitannins. By weight, herbs and spices beat all of it, which is why cloves and cinnamon sit at the top of the Phenol-Explorer tables, and also why nobody eats their way to a meaningful dose of cloves.

Content swings with cultivar, ripeness, growing conditions, storage and processing. Cooking moves it too, up or down depending on the compound and the method. Two bags of blueberries from the same shop aren't the same food, chemically.

What the rankings actually measure

A ranked list of antioxidant foods is almost always built on a measure of total antioxidant capacity, and ORAC is the best known one. The test takes an extract of the food, puts it in a tube with something that generates free radicals, and measures how long the extract holds them off. That's honest chemistry. It answers a narrow question.

The question it doesn't answer is what the food does in a person. The USDA withdrew its ORAC database in 2012 and said the values had no relevance to the effects of those compounds on human health, and that food and supplement companies were routinely misusing them in marketing. The agency that published the numbers is the one that took them down.

So a high score is a measure of potential in a tube, not a health outcome in a body. A tube isn't a person, and a result in vitro may not translate to anything in humans.

Does your body actually absorb them?

Mostly not in the form you ate. Digestion, the gut wall and your gut bacteria rework polyphenols before anything reaches the bloodstream, so what circulates is usually a metabolite rather than the original compound. A review of 97 human absorption studies put the recovered dose anywhere from 0.3% to 43%, depending on which polyphenol you mean. Gallic acid and the soy isoflavones are absorbed well. Proanthocyanidins, the galloylated catechins in tea and the anthocyanins that make berries blue are absorbed poorly.

That spread is the whole problem with a ranked list. A food can win on paper and deliver very little, and the number that won never mentions it.

Where to find them in the store

You don't need to redo your pantry. A few defaults do most of the work.

• Buy a lighter roast, or drink green tea, if you want to keep more chlorogenic acids and catechins. I've written up how coffee and tea actually compare.
• Pick natural cocoa powder over Dutch-processed. Alkalizing strips flavanols, and flavanols are where the best human evidence on cocoa sits.
• Keep oregano, cinnamon and cloves in the rack. Gram for gram they're the richest thing in the store, even though the gram you actually use is small.
• Choose extra virgin olive oil for anything uncooked. It carries hydroxytyrosol and oleuropein, and the harvest date on the bottle tells you more than the front label.
• Put walnuts or pecans in the snack drawer for ellagitannins.
• Add berries or red cabbage for anthocyanins, and accept that you absorb a small fraction of them.

Are antioxidant supplements as good as food?

No, and the evidence there is unusually clear for this field. The Cochrane review of antioxidant supplements pooled 78 randomised trials covering 296,707 people and found no evidence supporting them for primary or secondary prevention. Beta-carotene and vitamin E appeared to increase mortality, and higher doses of vitamin A may as well.

That's a different picture from the evidence on antioxidant-rich foods, and the difference is worth holding onto. A whole food delivers these compounds with fiber and everything else in the package, at a dose nobody had to choose. A capsule delivers one isolated compound at a dose somebody did choose. If you're considering one anyway, talk to a doctor or pharmacist first, because dose and interactions are real here in a way they aren't for eating berries.

What we still don't know

Whether a high laboratory score predicts anything for a person is still open, and I'd rather say that than dress it up. We also don't know how much of a berry's benefit is the polyphenols and how much is the fiber, the potassium, or simply that people who eat berries tend to eat differently in general.

Most of the human research is short, small and measured on markers rather than on outcomes people care about. That's the honest state of it, and it's why this site links the study instead of the press release.

Common questions about antioxidant rich foods

What is an ORAC score?

An ORAC score is a laboratory measure of antioxidant capacity, run on an extract of a food rather than in people. It describes how that extract behaves in a test tube. It doesn't describe what happens after a person eats the food, which is why the score and the benefit can point in different directions.

Why did the USDA withdraw its ORAC database?

The USDA took the database down in 2012, saying the values had no relevance to the effects of polyphenols and other bioactive compounds on human health. It also said food and dietary supplement companies were routinely misusing the numbers to promote products, which is exactly where most of the ranked lists online came from.

Are polyphenols the only antioxidants?

No. Polyphenols are the largest group of antioxidant compounds in the diet, and they're what berries, cocoa, tea, coffee and olive oil are known for. Antioxidant is the wider category, and it also includes vitamin C, vitamin E, the carotenoids and selenium.

What happens to antioxidants in my body?

Digestion, the gut wall and gut bacteria change polyphenols before they reach the bloodstream, so what circulates is usually a metabolite rather than the compound you ate. How much gets absorbed ranges from under one percent to over forty percent, depending on the polyphenol.

What foods have the most antioxidants by weight?

Herbs and spices, by a wide margin. Cloves, cinnamon and oregano rank at the top of the polyphenol tables gram for gram. The catch is portion size: you eat a teaspoon of cinnamon and a whole cup of berries, so the food that wins per gram rarely wins per meal.