Mark’s Daily Apple

Measuring Up: How to Calculate the Quality and Quantity of Antioxidant-Rich Foods

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The ORAC Gift of Health

Alright students, you’ve made it through biology 101, mastered the life and times of antioxidants and free radicals (and perhaps learned a little about the latest hip hop rivalry), but now its time to talk math, or specifically, how to measure the value of antioxidant-rich foods.

One method of measuring antioxidant capacity is the Oxygen Radical Absorbance Capacity (ORAC). Developed by the Baltimore-based National Institute of Aging, the calculation specifically measures the oxidative degradation of fluorescein (the stuff that the hotties on C.S.I. spray to detect the presence of blood, though not in this case) as it reacts with an agent called peroxyl radical (a free radical). Seem easy enough? Nice try. The reaction between the antioxidant and the free radical is then measured at 35 minute intervals to create a graphic curve that is then used as the basis for trolox equivalents (TE), or, in non-geek terms, the measure of a compounds potential for absorbing free radicals.

In 2004, the U.S. Department of Agriculture published a list of ORAC values for more than 100 common foods. Earning top billing on the ORAC list—meaning the items that contained the highest antioxidant value per serving—were small red beans, wild blueberries, red kidney beans, pinto beans, blueberries and cranberries. The list has since been updated to include 277 food items. (Here is the PDF report.)

While these calculations are certainly scientific, this method does have some caveats. For example, the ORAC value of a particular food can vary significantly depending on whether the food is measured based on units per gram dry weight or units per gram wet weight. When comparing grapes and raisins, for instance, raisins will clock in as having a higher antioxidant potential, simply because they are smaller than grapes and therefore more raisins are included in the calculation than would be if you were measuring for grapes. Enough to make your head spin isn’t it? Despite this nuance ORAC still reigns supreme as the vitamin-industry standard and as the one of the easiest ways to convey the antioxidant power of foods and supplements.

If you’re looking for a simpler solution—or at the very least a list of items that can up your antioxidant ante—think again. At the First International Congress on Antioxidant Methods held in 2004, 144 scientists representing 19 countries convened to establish uniform antioxidant measurement standards. In a new twist to the ‘how many people does it take to screw in a light bulb’ ditty (kind of), the researchers determined that while creating a uniform unit of measurement was necessary, there was no consensus on which of the approximately 100 different methods used to measure them was best. They did, however, agree to disagree and drafted a multi-disciplinary team consisting of scientists from the industry, academia and the government to develop and test new methods for measuring the value of antioxidants.

Although more than three years later we’re, uhhh, still waiting for those recommendations, the one thing the researchers at the meeting—and mom’s the world over—can agree upon? You just can’t go wrong if you eat your fruits and veggies!

LunaDiRimmel Flickr Photo (CC)

Further Reading:

Some Serious ORAC Value!

Calorie Restriction = Fewer Free Radicals?

Vitamin E Myths

Fight Those Free Radicals!

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Posted under: Aging, Health, How To, Nutrition, Prevention, Supplements