"You have to also look at what you're not getting" with organic foods, she said. "Maybe it's not a big difference nutritionally, but conventional products may have more pesticides."
And that's a particularly important issue for children, she said.
"We know that young children are getting the nutrition, whatever choice they make, but we also have to look at the pesticide issue," Rarback said. "A study published in Environmental Health Perspectives found that children eating conventionally grown fruit had pesticide residue in their urine, which decreased after just five days on an organic diet."
The production of organic food is subject to a variety of regulations, including those that govern the use of pesticides and other chemicals in fruits and vegetables and the use of medicines in animals, the authors of the review noted in their study, which will be published in the September issue of the American Journal of Clinical Nutrition.
Rarback indicated that the ability to get solid research on organic versus conventionally produced products is hampered by variations in the production process.
"There are so many variables," she said. "Where is something grown? Where is it shipped from? How long was it on the truck? There are going to be variables in terms of nutrition just from production methods."
There's more on food and the nutrients in food at the United States Department of Agriculture.
SOURCES: Alan Dangour, registered public health nutritionist, London School of Hygiene and Tropical Medicine; Connie Diekman, M.Ed, R.D., L.D., director, university nutrition, Washington University, St. Louis, and past president, American Dietetic Association; Sheah Rarback, R.D., director, nutrition, Mailman Center for Child Development, University of Miami Miller School of Medicine, Miami; Charles Benbrook, Ph.D., chief scientist, The Organic Center, Enterprise, Oregon; September 2009 American Journal of Clinical Nutrition