ORAC Antioxidant Ranking

ORAC (Oxygen Radical Absorbance Capacity) measures a food's ability to neutralise peroxyl radicals in a lab setting, using fluorescein dye. The result is expressed in µmol Trolox Equivalents (TE) per 100g — the higher the number, the more free radicals the food can absorb in vitro. It was developed at the Jean Mayer USDA Human Nutrition Research Center and was widely used from the 1990s through the 2000s as a standardised antioxidant benchmark.

The USDA withdrew ORAC data in May 2012 because the values were being heavily misused by the food and supplement industry to make unsubstantiated health claims. The agency clarified that ORAC values "are routinely misused by food and dietary supplement manufacturing companies to promote their products and by consumers to guide food and supplement choices." The data also failed to demonstrate a consistent relationship between ORAC scores and actual health outcomes in humans. The values here are preserved for informational and research comparison purposes only.

No — ORAC, FRAP, and DPPH are all different antioxidant assays that use different chemical mechanisms and radical species. They broadly correlate with polyphenol content but produce different rankings. ORAC measures peroxyl radical absorbance; FRAP measures ferric ion reduction; DPPH measures hydrogen atom or electron transfer capacity. No single assay captures the full picture of antioxidant activity in food.

With significant caution — and for reasons that go deeper than just the marketing misuse. Dr. Michael Greger at NutritionFacts.org points out that the ORAC test measures how foods slow down a specific chemical oxidation reaction in a test tube that "doesn't actually occur in nature." When researchers compared standard ORAC rankings to actual cellular antioxidant activity — how well foods protect living cells — the results were strikingly different. Spinach ranked first in ORAC, but didn't even make the top ten for cellular antioxidant activity. Beets, which score more moderately on ORAC, ranked first in cellular activity. This means the foods ORAC would suggest prioritising aren't necessarily the most protective inside your body. That said, many high-ORAC foods like berries, dark chocolate, legumes, and tea are also genuinely polyphenol-rich and health-promoting — just not necessarily because of their ORAC score specifically. Let food diversity guide your plate rather than any single score.

The USDA previously suggested a range of 3,000–5,000 ORAC units per day as a rough target, but this recommendation was withdrawn along with the database in 2012 because the scientific basis was considered insufficient. No official body currently endorses a daily ORAC target. A more reliable approach is to eat 5–9 servings of varied fruits and vegetables daily, which naturally provides a broad range of antioxidants without needing to track any specific score.

ORAC scores broadly correlate with total polyphenol content because polyphenols are the primary antioxidant compounds in plant foods. However, the correlation is not perfect — some polyphenols are better free-radical scavengers than others, and non-polyphenol antioxidants like vitamin C and carotenoids also contribute to ORAC values. High-ORAC foods are generally polyphenol-rich, but not all high-polyphenol foods rank equally well on ORAC.