Fruits and veggies grown organically show significantly higher levels of cancer-fighting antioxidants than conventionally grown foods, according to a new study of corn, strawberries and marionberries, a type of blackberry. The findings appear in the Journal of Agricultural and Food Chemistry. The research suggests that pesticides and herbicides actually thwart the production of phenolics – chemicals that act as a plant’s natural defense and also happen to be good for our health. Fertilizers, however, seem to boost the levels of anti-cancer compounds.

The need for these natural defenses decreases with the use of herbicides and pesticides in conventional agriculture. This decrease is reflected in the total amount of antioxidants the plants produce. “This helps explain why the level of antioxidants is so much higher in organically grown food,” says Alyson Mitchell, PhD, a food scientist at the University of California, Davis. “By synthetically protecting the produce from these pests, we decrease their need to produce antioxidants. It suggests that maybe we are doing something to our food inadvertently.”

The investigation compared the total antioxidants found in foods grown organically (using no herbicides, pesticides or fertilizers) to foods grown sustainably (in this study fertilizers but no herbicides or pesticides were used) and conventionally (using synthetic chemicals to protect the plants and increase yield). The results showed a significant increase in antioxidants in organic and sustainably grown foods versus conventionally grown foods. The levels of antioxidants in sustainably grown corn were 58.5% higher than conventionally grown corn. Organically and sustainably grown marionberries had approximately 50% more antioxidants than conventionally grown berries. Sustainably and organically grown strawberries showed about 19% more antioxidants than conventionally grown strawberries.

American Chemical Society, March 3, 2003