Are ORAC values a better way to measure the total antioxidant capacity of foods just another marketing ploy? Learn what these numbers mean for your health.
Are ORAC values a better way to measure the total antioxidant capacity of foods just another marketing ploy? Learn what these numbers mean for your health.
If you spend a lot of time reading about nutrition (which I do), it starts to feel as if we're all in some sort of contest to see who can eat the most antioxidants. Those who are interested in (dare I say, obsessed with?) antioxidant nutrition will often talk about a food's ORAC value. As in, "Wild blueberries have an ORAC value of 9,621, while regular blueberries only have an ORAC of 4,669!" What on earth are these people talking about?
ORAC stands for Oxygen Radical Absorbance Capacity. It's a lab test that attempts to quantify the "total antioxidant capacity" (TAC) of a food by placing a sample of the food in a test tube, along with certain molecules that generate free radical activity and certain other molecules that are vulnerable to oxidation . After a while, they measure how well the sample protected the vulnerable molecules from oxidation by the free radicals. The less free radical damage there is, the higher the antioxidant capacity of the test substance. There are actually a handful of different tests designed to measure total antioxidant capacity in this way, but the ORAC is probably the best known and most popular.
The nice thing about this method is that it measures the antioxidant activity of a food rather than the levels of specific nutrients, such as vitamin C or E. After all, there are thousands of unique antioxidant compounds in plants, most of which we haven’t even discovered yet. There’s no way we could measure them all individually. This approach would also capture any synergistic effects between the various nutrients—ways in which nutrients are more effective in combination than they are individually.
The lab that developed one of these tests has measured the ORAC values in hundreds of foods and spices and published those values in a database, which you can find online. Some of the results might surprise you. For example, who would have thought that whole grain bread has a higher antioxidant capacity than bean sprouts? Or that kidney beans pack four times the antioxidant punch of broccoli?
Some of the results are a bit misleading. For example, you’ll find spices like cinnamon and cloves with 6-digit ORAC values. However, all of the ORAC scores refer to 100-gram servings. Once you convert these into the amounts you’d typically consume in a meal, cinnamon and cloves are comparable to the antioxidant activity of small apple or pear.
Once this database was published, it was inevitable that people (as well as marketers) would start competing to see who could rack up the highest score.
Meanwhile, there are big questions about the relevance of the ORAC values to human health. For one thing, this test is performed in a test tube. We don’t know how—or even whether—these foods interact with free radicals in the body once they’ve been consumed. Foods like chocolate and olive oil, for example, are chockful of antioxidants called polyphenols. Put these foods in a test tube and they mop up free radicals like crazy. Surprisingly, however, they do not have much direct antioxidant activity in the body.
Similarly, there’s no evidence that super high-ORAC foods or diets are super-beneficial—because the body can only use so many antioxidants at a time. Dr. Ronald Prior, an antioxidant researcher who worked on ORAC reports for the USDA, estimates that anything above about 5,000 ORAC units a day is probably overkill. There’s even research to suggest that excessive amounts of antioxidants—especially from extracts or supplements—may actually be disruptive to optimal function.
See Also: Can You Get Too Many Antioxidants?
Although the USDA once hosted a table of ORAC values on its website, they have since taken this database table down, citing unanswered questions about the biological relevance of the ORAC values, combined with the potential for misunderstandings by consumer and misuse by marketers. You’ll still find health bloggers and food and supplement marketers waxing poetic about high ORAC values, but you don’t hear a whole lot about them from serious nutrition scientists anymore. I certainly wouldn't pay a lot of money for a food or supplement based solely on its ORAC number.
Keep in mind that, while antioxidants are certainly beneficial, they are only one of many aspects of good nutrition that deserve our attention. You can’t define the quality of your diet solely by its ORAC score. If you’re eating a balanced and varied diet, including plenty of fresh fruits, vegetables, and other whole foods, your ORAC score will take care of itself. No superfruits or supplements required!
References: EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the substantiation of health claims related to various food(s)/food constituent(s) and protection of cells from premature aging, antioxidant activity, antioxidant content and antioxidant properties, and protection of DNA, proteins and lipids from oxidative damage. EFSA Journal, Vol 8, No. 2, 2010, pp: 1489. View article.