Organic food is a relatively new area of research, emerging only over the last decade or two, with little funding and often-conflicting results.

A headline-making British study, published last summer in the American Journal of Clinical Nutrition, found no significant nutritional difference between organic and conventional food.

It's difficult to say for sure whether organic foods are nutritionally superior to conventional, says Carl Pike, a Franklin & Marshall College botany professor.

"I don't think there is ever going to be a single, simple answer," he says.

Many past organic studies haven't stood up to scientific scrutiny, Pike says. Some were too short; the sample size for others was too small.

"There are so many things that influence the nutrient content of a tomato," Pike says, citing soil, crop variety, weather and handling conditions. "We may not even know all of them."

Some more tightly focused, recent studies, he says, have been useful and well-designed. Studies conducted at the Unive rsity of California, Davis, have shown more antioxidants in organic tomatoes and more vitamin C in organic kiwi.

Fresh, local fruits and vegetables are the most healthful, whether organic or not, says Jacqui L. Zimmerman, a registered dietitian with Lancaster General Health. Nutrients in produce break down over time, she says.

"The most nutritious produce is going to be the produce you [eat] as close as possible to when it was taken out of the ground," she says.

But many consumers say they don't need hard science to tell them organics are a smarter choice.

Organic veterinarian Dr. Hubert Karreman says logic tells him it's better to limit the presence of chemicals on his family's plates.

"I'm not going to wait on that proof," he says.

Contact Lancaster Newspapers staff writer Mary Beth Schweigert at mschweigert@lnpnews.com.