What Is an ORAC Rating?

Developed by chemist and physician Dr. Guohua Cao the Oxygen Radical Absorbance Capacity ORAC rating is a laboratory analysis that provides an overall measure of a food's antioxidant activity. The higher the ORAC score, the greater is the food's antioxidant capacity. ORAC tests are often used to compare the antioxidant activities of different foods (fruits, vegetables, juices, wines, etc.).

Two problems exist with this test:

• ORAC analyses are not extremely precise
• different laboratories conduct ORAC testing in different ways, and often produce markedly different results

Not Very Precise

Oxygen Radical Absorbance Capacity (ORAC) is a laboratory analysis that provides an overall measure of a food's antioxidant activity. The test works by challenging a food product with an oxidizing agent, and then measuring the overall capacity of that food to resist oxidation.

The higher the ORAC rating score, the greater is the food's antioxidant capacity. Several such measures of "total" antioxidant activity have been developed. None are definitive. ORAC has gained the widest acceptance in commercial circles but are ORAC rating scores all they're cracked up to be?

ORAC tests are often used to compare the antioxidant activities of different foods (fruits, vegetables, juices, wines, etc.). Such comparisons can be valuable, but they do carry limitations.

First, ORAC analyses are not extremely precise. When a given food product is tested multiple times in a given laboratory, variation in ORAC rating score from one sample to the next is often on the order of 10-15%. Second, different laboratories conduct ORAC testing in different ways, and often produce markedly different results. And third, different orange juices, for example, that were manufactured and diluted in different ways, and stored under different conditions, can actually have very different antioxidant activities, such that it is difficult to assign a meaningful ORAC score to orange juice in general.

Nevertheless, comparisons based on ORAC testing can be meaningful when like products are compared (for example, when comparisons are made between a number of fruit juices or fruit-based products); when all ORAC analyses are conducted in a single, qualified laboratory using the same analytical methods, and importantly when the ORAC rating values reported pertain to equal amounts of product (for example, all the ORAC values are presented on a per ounce or per 100 gram basis).

Under these circumstances, large differences in ORAC rating scores (particularly differences on the order of 3-10 fold) indicate meaningful differences in true antioxidant activity.

When considering ORAC as a basis for comparision make sure these 3 important controls are considered:

• comparison is made between like products i.e. fruit vs. fruit, juice vs. juice
• analyses are conducted in a single, qualified laboratory using the same analytical methods
• product comparisons must be for equal amounts

**Warnings**

Some manufacturers of certain juice supplements are using ORAC rating as the sole analyses of the product being superior to tablet supplements. Let’s take a further look...

• First off; remember that just because it sounds like a juice supplement would be more “easily” absorbed that is not generally the fact. Different vitamins and minerals have different absorption rates no matter if they come from tablet, liquid, powder, or food. Most medications come in a tablet form. A well made tablet has proven to be highly effective for pharmaceuticals. Why would a vitamin supplement be any different?
• Indeed, if liquids were simply absorbed directly in to the bloodstream, as some supplement companies claim, would the same happen when you ate soup? Bottom line – the science just isn’t there when it comes to liquid supplements.
• The supplement industry itself originated on account of published studies in the scientific literature that contributed to the knowledge and insight into nutritional elements. With the hundreds of studies connecting calcium and vitamin D supplements with bone health, it is hard to dispute that tableted supplements provide an effective delivery system. If tablets weren't any good, why did the researchers get positive results? If liquid or spray supplements are so much better, why are they rarely, if ever, used in published scientific research?
• Keep in mind that we are speaking of multiminerals and multivitamin formulations. There may be certain products that may be appropriate in a liquid (just as some medications are liquid). However, these are the exceptions, not the rule.
  
• Liquid supplement promoters often contend that liquids are better because they don't contain fillers (excipients used in tablets for disintegration, form, binding, coating, etc). That is a ridiculous argument since liquid supplements require even more "other" ingredients such as emulsifiers, solvents, preservatives, stabilizing agents, coloring, flavoring, etc. The more ingredients in a liquid supplement, the more excipients that may be required.
• Lastly, as rated by the 4th edition Nutrisearch Comparative Guide to Nutritional Supplements top 13 vitamin supplements of 1500 rated – none are in a liquid form.
  

ORAC scale and rating of common fruits & vegetables.