erries and corn that are cultivated without pesticides contain a significantly greater amount of polyphenolic antioxidants than conventionally grown fruits and vegetables, University of California-Davis scientists report.
The marionberries (a type of blackberry), strawberries, and corn that researchers studied contained as much as 58 percent more polyphenolics.
The researchers, led by Alyson Mitchell, assistant professor of food science, found that the produce grown organically or sustainably - with fertilizers but without pesticides - measured higher levels of ascorbic acid, or vitamin C, as well.
The fruit and corn were grown in matched plots by a farm in Oregon, then frozen, freeze-dried, or air-dried before the nutrients were measured.
Frozen sustainably-grown and organic marionberries and corn contained 50 to 58 percent more polyphenolics than conventionally grown crops from neighboring plots.
Sustainably-grown frozen strawberries contained 19 percent more polyphenolics than conventional fruit. These levels were nutritionally significant.
While researchers know that a diet high in polyphenolics can reduce the risk of some cancers and heart disease, they aren’t sure how.
“We know they’re beneficial, but we don’t know what types of polyphenolics are beneficial, or in what quantities,” Mitchell said.
Mitchell hypothesized that crops grown without pesticides or herbicides might make more polyphenolics because they are more likely to be stressed by insects or other pests.
Polyphenolics are natural chemicals produced by plants as by-products of other processes. When plants are stressed, they produce higher levels of the bitter-tasting polyphenolics, and drive away pests.
