Uproar over study on organic food

For years, healthful-food advocates have said organic food is more nutritious than conventionally grown.

But that claim — trumpeted on the Web sites of organizations ranging from the national Organic Trade Association to the Seattle-based PCC Natural Markets — is being challenged by a comprehensive new study released last week.

Now the healthful-eating crowd is up in arms. Not only did researchers reach the wrong conclusion, advocates say, they didn't even ask the right questions. Such as: Why, exactly, do people buy organic?

Many advocates say it's not so much about what's in the food; it's about what isn't.

"There's a larger reason to buy organic food, and nutrition is just one piece of it," said Laura Niemi of Seattle Tilth Association.

The study, conducted by British researchers and published in the peer-reviewed American Journal of Clinical Nutrition, examined all the relevant research between 1958 and 2008, eliminating studies the authors deemed not scientifically sound. It has been billed as the most comprehensive review of the nutrition question to date.

Researchers concluded "there is no evidence of a difference" between organic and conventionally grown produce in 20 of 23 nutrient categories, including vitamin C, calcium and potassium. The researchers had similar results when comparing meats. Any nutritional differences they did find were not significant, the researchers said.

"Our review indicates that there is currently no evidence to support the selection of organically over conventionally produced foods on the basis of nutritional superiority," the lead researcher said in a news release. The study was undertaken "because there is currently no independent authoritative statement" on the nutrition question, the researchers said.

The study was conducted by the London School of Hygiene and Tropical Medicine, the country's national school of public health. It was funded by the Food Standards Agency, an independently operating government department "set up to protect the public's health and consumer interests."

Media reports on the study have appeared on CNN and in newspapers stretching from Chicago to Australia. Meanwhile, the blogosphere is buzzing with criticism. Some worry that publicity about the results could affect consumer buying habits.

The main problem with the study, critics say, is that nutrition is only a small part of organic's appeal. The researchers did not examine, for example, what effect chemical fertilizers and pesticides — used in growing conventional crops — have on consumers. Nor did they look at the environmental effects of each growing method.

"Nutritional quality is one of many potential variables related to the advantages of organic food," Margaret Wittenberg, global vice president of quality standards for Whole Foods Market, said in a statement. "But for us, there are already plenty of well-documented reasons to choose organic."

Advocates pointed to a study completed last year by The Organic Center that reached a different conclusion. Like the British study, these researchers examined the results of previous studies but went back only to the 1980s and used different methodology. For example, they focused exclusively on "matched pairs" of organic and conventional foods — that is, "crops grown on nearby farms, on the same type of soil, with the same irrigation systems and harvest timing."

The conclusion? "Yes, organic plant-based foods are, on average, more nutritious."

The Organic Center's mission is "conversion of agriculture to organic methods, improved health for the earth and its inhabitants, and greater awareness of and demand for organic products."

Pointing to the conclusions of the The Organic Center's report, Diana Crane, of PCC Natural Markets, said the British report was "not balanced."

"I don't see it as a matter of taking sides," Crane added. "I see it as being informed, knowing what's reputable, and in some cases what just makes common sense. ... Organic has intuitively to be better for you."

While criticism of the British results abound, some have chosen to look at the bright side.

Debra Boutin, chair of Bastyr University's Department of Nutrition and Exercise Science, said that while the results may have been overblown in media reports, she's not about to dispute the conclusions.

Her priority is to get people to eat their fruits and vegetables, whether they're well-to-do fine-diners or struggling shoppers. If they can get as many nutrients from conventionally grown as they can from organic, she said, "that's a good thing. They're equally good for us."

Maureen O'Hagan: 206-464-2562 or mohagan@seattletimes.com