Is that right? Oregano has more antioxidants than spinach?
"Just half a teaspoon of dried oregano has as many antioxidants as 3 cups of spinach."
That quote, attributed to dietitian Wendy Bazilian, appears in an article about "The World's Healthiest Diet" in the March issue of Ladies' Home Journal. The diet in question is of the Mediterranean variety, which I've written about and which many nutrition experts believe is the most healthful approach to eating.
That oregano/spinach comparison got me wondering. How are antioxidants in food actually measured? And what does the relative amount of antioxidants in a food mean in terms of health for the humans eating that food?
My curiosity was compounded by the fact that Wendy Bazilian appears as a nutrition expert on the Web site of McCormick spices. In magazine ads and on that site, McCormick's made much of the antioxidant power of spices. As any consumer today knows, antioxidant content has become a big selling point for all kinds of foods -- despite the fact that nobody quite knows exactly how these compounds, of which there are thousands, actually might work to keep us healthy.
Antioxidants are believed to counter the damage that naturally occurs within our bodies during the process of living. They're thought to mitigate damage caused by free radicals, unhinged oxygen molecules that may cause inflammation or other harm to our cells.
But science hasn't yet figured out the details of those interactions. One of the big unknowns is how a compound's antioxidant activity in a laboratory test tube translates to any such activity in our bodies.
Another big question is how best to measure antioxidant content. Perhaps the most popular scale in use today is the ORAC assay. Dried oregano's ORAC (for Oxygen Radical Absorbance Capacity) score is 200,129 (micromoles of Trolox Equivalents for 100 grams); raw spinach's is just 1,515 of those units. So, by that measure, oregano is clearly the antioxidant victor.
But when I looked up both foods on NutritionData.com, I got a different picture. Whereas a teaspoon of dried oregano has just 1 percent of the Daily Value for the antioxidant vitamins A and C, a cup of spinach has 56 percent of the DV for Vitamin A and 14 percent of the DV for Vitamin C. And the nutrition facts paint a fuller picture than a mere accounting of antioxidant values. For instance, they show that the cup of spinach supplies nearly twice the Vitamin K we need in a day, while oregano delivers only 8 percent of that DV. Vitamin K, though essential to bone health and blood-clot formation, isn't usually considered an antioxidant.
Jeffrey Blumberg, director of the Antioxidants Research Laboratory at Tufts University in Boston, told me that various methods of measuring antioxidant capacity will assess foods differently, as each of them values some kinds of antioxidants over others. In any case, he says, antioxidant content is just one component of a food's nutritional value and shouldn't be the reason you choose one food -- say, dried oregano -- over another. Many of the antioxidants present in a food might not be bioavailable -- usable by the body -- he notes.
And just looking for antioxidant content may blind us to the other nutritional values a food may offer. Even a vitamin classified as an antioxidant, such as Vitamin C, helps our bodies in ways that have nothing to do with antioxidant activity. Such nutrients, Blumberg notes, "have different kinds of beneficial bioactive effects" that have nothing to do with antioxidant effects.
"Some people have suggested that there are really simple ways to look at antioxidants and express their values," Blumberg says. "I would argue that when you simplify things in that manner, you add to the confusion."
Blumberg would rather see me evaluate a food's total nutritional makeup using a source such as NutritionData.com or the USDA National Nutrient Database for Standard Reference than to rely on an antioxidant scale to get a full picture of that food's likely benefits.
As for oregano versus spinach, Blumberg says, "I would never say 'skip the spinach and eat oregano.' If you want to make me really happy, give me a recipe that adds oregano to spinach."
Jennifer LaRue Huget
February 12, 2010; 7:00 AM ET
Categories: Is That Right? , Nutrition and Fitness
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