Dietary antioxidants are a variety of chemicals (eg. vitamins E, C, phenols, flavonoids ) with a capacity to scavenge free radicals and other reactive oxygen species that are associated with health disorders.

USDA researchers measured total antioxidant capacity of foods, namely, fresh fruits, vegetables, nuts and dried fruits collected from the US markets.

Total antioxidant capacity was based on ORAC assays. They measured total antioxidant capacity of the samples based on the sum of water and lipid soluble antioxidants. The fruits, nuts, rice bran and vegetables (except for Russet potato, broccoli, carrot and tomato which were in their cooked form) were freeze-dried before analysis.

Below is a list of fruits, vegetables, nuts and other food stuffs with estimates of their total antioxidant capacity evaluated in the study. In each food catagory, they are ordered from the highest to the lowest total antioxidant activity. Overall, rice bran has the highest antioxidants in all the foods evaluated in this study. Next best ones are pecans, plums and berries.

Antioxidants in Foods

Antioxidant sourcesTotal antioxidant capacity (µmol TE/g)
Fresh Fruits 
Plum 62.4
Blueberry 62.2
Rasperry 49.3
Strawberry 35.8
Avocado 19.3
Navel orange 18.1
Grapefruit 15.5
Kiwi 9.2
Cantaloupe 3.1
Honeydew 2.4
Watermelon 1.4
Fresh Vegetables 
Broccoli 15.9
Potato, Russet 13.2
Carrot 12.2
Radish 9.5
Celery 5.7
Lettuce, Iceberg 4.5
Baby carrot 4.4
Tomato 3.4
Pecan 179
Pistachio 79.8
Almond 44.5
Cashew 20
Macadamia 17
Dried Fruits and other food stuffs 
Rice bran 242.9
Prune 85.8
Date 39
Raisin 30.4

Table adapted from: Xianli Wu, Liwei Gu, Joanne Holden, David B. Haytowitz, Susan E. Gebhardt, Gary Beecher and R.L.Ronald L. Prior. 2004. Development of a database for total antioxidant capacity in foods: a preliminary study. Journal of Food Composition and Analysis, Vol 17: 3-4 , 407-422.