Oxygen radical absorbance capacity

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Oxygen Radical Absorbance Capacity (ORAC) is a method of measuring antioxidant contents in different foods. It was developed at the National Institute on Aging in Baltimore, Maryland. High scoring foods include Acai, Cerasus (Montmorency tart cherries) prunes, raisins, blueberries, kale, spinach and cocoa. Foods with higher ORAC values per 100 grams include wild blueberries, pomegranates and black raspberries.

Natural fruits typically score between 500 and 900 ORAC units per 100 grams. The Food and Drug Administration (FDA) has recently suggested that the Americans increase their consumption of antioxidants to 7000 ORAC units daily which is near 5-10 servings of colorful fruits and vegetables contributing to overall health and to help curb the cancer epidemic. [Reference Needed]

In 2004, scientists with the US Department of Agriculture (References, Wu et al.) published an updated list of ORAC values for over 100 common foods (fruits, vegetables, nuts, seeds, spices, grains, etc.). Values were reported as micromoles of Trolox equivalents (TE, vitamin E derivative) per gram both for lipid-soluble ("lipophilic" as for carotenoids) and water-soluble ("hydrophilic" as for phenolics) antioxidant chemicals in foods, thus were a sum of lipophilic and hydrophilic values or total ORAC.

The values are considered to be more accurate than previously published ORAC numbers because lipophilic values were being included for the first time. The data of Wu et al. showed that all plants have variable amounts of both lipophilic and hydrophilic phytochemicals with antioxidant properties contributing to total ORAC.

The range of ORAC for common fruits was around 140 TE per 100 grams (watermelon) to 1,800 (orange). For vegetables or legumes, it was 115 (cucumber) to 14,400 (red kidney bean); for nuts, 2,000 (cashew) to 17,940 (pecan); and for dried fruits, 3,037 (raisin) to 8,578 (prune).

Spices (clove, cinnamon) showed the highest ORAC values (>250,000, converted to TE per 100 grams) whereas, among commonly eaten foods, dark berries (known to be rich in phenolics), such as cranberry and lowbush blueberry, were the highest as a group (around 9,300 TE per 100 grams). By comparison, different species of apples had ORAC values of 4,275 TE per 100 grams or less, white potato was under 1,100, peanut was 3,166 and tomato about 400.

In their 2005 book (References), Young et al. report ORAC for dried wolfberry as 30,300 TE per 100 grams, indicating exceptional antioxidant strength likely resulting from the synergy of wolfberry's diversity of antioxidant phytochemicals including rich contents of lipophilic carotenoids, hydrophilic phenolics and vitamin C. A letter from Brunswick Laboratories indicate a ORAC value of 3,380 TE for 100 grams. of YL Berry Young Juice. The above mentionned figure of 30,300 was for a 32 oz bottle.

The highest ORAC value mesured is on Momontrency tart cherry concentrate at 16,500 TE per 100 grams.

Among high-antioxidant berries and fruits whose ORAC values have been reported as marketing information (unconfirmed by scientific peer-review) are açaí at 34,000 (freeze dried powder, Sambazon) and pomegranate at 10,500 (References, Brunswick Laboratories).

Cocoa has a high ORAC value, giving dark chocolate a value of 13,120 and milk chocolate 6,740. [1]

Recently, a number of health food companies have capitalized on the ORAC rating, with dozens selling concentrated supplements that they claim to be "the number one ORAC product", some purporting that their supplements have a value of more than 25,000 ORAC units per 100 gram serving. It is not known whether such values are accurate or if such concentrated antioxidants can be absorbed by the human body as effectively as those found in natural foods.

[edit] References

Commercial ORAC assays and antioxidant information, Brunswick Laboratories Inc., [2]
Huang D, Ou B, Prior RL. The chemistry behind antioxidant capacity assays. J Agric Food Chem. 2005 Mar 23;53(6):1841-56 PMID 15769103
Wu X, Beecher GR, Holden JM, Haytowitz DB, Gebhardt SE, Prior RL. Lipophilic and hydrophilic antioxidant capacities of common foods in the United States. J Agric Food Chem 2004 Jun 16;52(12):4026-37 PMID 15186133
Young G, Lawrence R, Schreuder M (2005). Discovery of the Ultimate Superfood. Essential Science Publishing. ISBN 0-943685-44-3.