Differences between organic and conventional produce found

New research on specific sample groups shows some organic produce may have an added health benefit over conventionally grown counterparts, according to researchers presenting at the Institute of Food Technologists Annual Meeting and Food Expo. But inherent inconsistencies associated with organic farming make general comparisons inappropriate.

In her study of organic and conventionally grown tomatoes, Alyson Mitchell, a food chemist at University of California at Davis, found organic tomatoes had higher levels of secondary plant metabolites and higher levels of vitamin C.

"In looking at the (California) supermarket varieties of broccoli, we also found significantly higher levels of the flavonoids in organic broccoli," said Mitchell.

As defence mechanisms in plants used to fend off infection and pests, metabolites in the body are thought to offer health benefits including reduced risk of heart attacks and coronary heart disease. Flavonoids are metabolites known to act in the body as antioxidants.

"It is recognised that high-intensity agricultural practices can disrupt the natural production of secondary metabolites involved in plant defence mechanisms," Mitchell said.

No significant differences were seen between organic and conventional green peppers, Mitchell reported.

The findings add to a small body of literature showing higher levels of antioxidants in some organic produce, including research out of the UC-Davis showing higher levels of phenols in some berries.

Building solid evidence confirming the benefits of organic fruits and vegetables over conventionally grown produce is hampered by wide variances in organic farming, ranging from soil and climate differences to variations in crops, seasons and farmer philosophies, said Diane Barrett, also a researcher with the UC-Davis department of food science and technology.