The buzzword today is "antioxidants." You can find the term plastered on food labels and dietary supplements, all over the media, and even in smart phone apps, which can help you identify the antioxidant values of hundreds of foods as you shop.
Plant foods contain phytochemicals--nonessential nutrients that may be bioactive and affect human health. The largest group of phytochemicals is the polyphenols, comprised mainly of the flavonoids, which are commonly called "dietary antioxidants."
The antioxidant race
The establishment of antioxidant levels in foods is based on chemical laboratory analysis, such as ORAC (Oxygen Radical Absorbance Capacity)--a common analysis technique that measures the total antioxidant capacity in foods or phytochemicals. So, when a food or dietary supplement company talks about the "high antioxidant" level of their product, whether it's blueberries or goji berries, the level is usually based on a laboratory analysis, such as ORAC.
So what's the problem with boasting about high antioxidant levels? It can be misleading, says Jeffrey B. Blumberg, Ph.D., Professor and Director of the Antioxidants Research Laboratory at Tufts University (Medford, Mass.), because, "Many of these compounds act to quench free radicals effectively only in vitro (test tube experiments), not in vivo (living organism experiments)."
He notes that these compounds are certainly bioactive, serving to fight inflammation, increase detoxification, and trigger some antioxidant enzymes. But the ORAC is a test tube analysis, which does not account for bioavailability and metabolism in the body. Scientists have yet to fully understand what compounds are found in particular foods, as well as how they are absorbed and broken down, and what amount gets into the tissues.
Shopping for antioxidants
The emphasis on "high-antioxidant" foods has encouraged people to shop for foods based on their reported antioxidant levels. This is why the U.S. Department of Agriculture recently removed the USDA ORAC Database for Selected Foods from its website, citing mounting evidence that the antioxidant values listed have no relevance on the effects of specific bioactive compounds on human health.
The USDA reports that ORAC values are routinely misused by food and dietary supplement manufacturing companies to promote their products, and by consumers to guide their selections.
What really happens in your body?
Scientists have embarked on a new journey in the world of plant research. They are now moving out of the test tube and into the human body, as they try to solve the mystery about what happens to all of those phytochemicals in plant foods once you eat them.
An emerging body of research is exploring the effects of consuming particular plant foods, such as walnuts, blueberries, strawberries, tomatoes and soy, on human health.
"We have learned that for many phytochemicals, it's not the parent plant compound that is bioactive; it is the metabolites created by the gut flora, liver, lung, retina, or other tissues in the body," says Blumberg, who reports that conversion of these metabolites also may be related to nutrigenomics--the field of science that examines the effects of foods on an individual's genetic makeup. For example, someday scientists may be able to tell you if you have the ability to convert phytochemicals from a food into cancer-preventing compounds.
The whole food, and nothing but the food
To be sure, phytochemicals and antioxidants are good for you; it's just that we're putting too much emphasis on one aspect of eating plant foods. Blumberg says, "People may think that it's no longer the vitamins, minerals or fiber, but only the phytochemicals that promote health. But the reason plant foods are good for you is because of everything they contain. There is synergy for all of these ingredients--synergies between ingredients within one food and between multiple foods; that's why the Dietary Guidelines recommends we consume a diversity of fruits, vegetables, and whole grains."
This synergy of nutrients in foods also explains why it's difficult to gain the same benefits from eating isolated nutrients--vitamins, minerals, phytochemicals--in supplement form, compared to eating the whole food.
Studies have indicated that foods rich in phytochemicals may reduce the risk of several chronic conditions, including neurodegenerative diseases, atherosclerosis, and certain forms of cancer. In fact, some research has found that dietary antioxidant levels in food are linked to lower disease risk in humans.
For example, a 2012 Swedish study published in Stroke, which included more than 31,000 women, assessed the impact of dietary total antioxidant capacity on risk of stroke incidence. Researchers found that the highest intake of antioxidants was linked with a lower risk of stroke in both cardiovascular disease (CVD)-free women and women with CVD history.
The bottom line
Antioxidants are just the tip of the iceberg in regard to the benefits of eating more whole, plant foods, including fruits, vegetables, whole grains, legumes, seeds, nuts, tea, herbs and spices. And the best advice is to eat them frequently with a wide variety.
By choosing from an array of plant foods in all colors of the rainbow, you can receive the benefits of nutrients working together in your body. This is just what the USDA had in mind when they developed MyPlate, which tells you to fill your plate at least three-fourths full of plant foods.
(Reprinted with permission from Environmental Nutrition, a monthly publication of Belvoir Media Group, LLC. 800-829-5384. http://www.EnvironmentalNutrition.com.)