BOULDER — Do organic fruits and vegetables have more nutrients than conventional ones?

A recent Stanford University study says no — a finding that has created controversy in the local organic industry.

A scientist at the Organic Center started in Boulder says yes — organic fruits and vegetables can have as much as 30 percent more nutritional value.

Organic apples, strawberries, grapes, tomatoes, milk, carrots and grains have 10 percent to 30 percent more nutrients, according to Chuck Benbrook, chief scientist at the Organic Center.

Benbrook points to a key 2011 study done in the United Kingdom as one that supports his analysis. He says Stanford researchers cite that study but don’t mention its findings.

“Vitamin C, antioxidants and phenolic acids tend to be higher in organic food about 60 percent to 80 percent of the time,” Benbrook said in a 12-page paper responding to the Stanford University study. “Vitamin A and protein are higher in conventional food 50 percent to 80 percent of the time.”

The Organic Center is an industry trade group started in Boulder in 2002. It merged with the member supported Organic Trade Association at the beginning of September and moved to Washington, D.C.

Stanford researchers were not available for comment about the new Stanford study, which was published Tuesday, Sept. 4, in the Annals of Internal Medicine, a trade publication. Researchers said they analyzed information from 237 existing studies to come up with the new finding. Of those - 17 studies were of people who consumed both organic and conventional food and 223 studies compared the nutrient levels or the bacterial, fungal or pesticide contamination of various foods grown organically or conventionally, according to a press statement on the university’s website.

“There isn’t much difference between organic and conventional foods, if you’re an adult and making a decision based solely on your health,” Dena Bravata, a doctor and the senior author of the study, said in the press statement.

Stanford researchers used no outside funding for the study, which was led by the university’s Center for Health Policy, according to the press statement.

Rigorous studies that measure the same crops in the same fields with the same soil and other inputs should be used to evaluate nutritional value of organic fruits and vegetables, said Mark Retzloff, a co-founder and chairman of Alfalfa’s Market Inc. natural grocery store and chairman of the Organic Center.

But Retzloff feels the Stanford study does a good job in talking about pesticide use to grow all fruits and vegetables.

Pesticide levels on all fruits and vegetables sold in the United States fall below federal limits set by the Environmental Protection Agency for both organic and nonorganic food, the Stanford study points out.

“There were lots of positive things that came out of the study,” Retzloff said. “They’re talking about the use of pesticides and, by far, all of the studies I’ve seen, that’s the No. 1 thing I’ve seen that consumers respond to.”

Steve Hoffman, owner of Compass Natural LLC marketing firm in Boulder and a founder of the Organic Center, said the Stanford study is too narrow and doesn’t take into account the social benefits of organic food and farming.

“I question why they didn’t look at the environmental costs of agriculture, the herbicides in the water, the air and the rain … the chemical pollution caused by conventional agriculture,” Hoffman said. “Those are the external costs borne by society and the taxpayer.”

The new study may have been controversial locally, but it’s not expected to have a negative impact on the organic industry, said Sonja Tuitele, a spokeswoman for Aurora Organic Dairy Corp., a Boulder-based dairy operation that sells organic milk to grocery stores to be sold under various store labels.

Educated consumers of organic products will continue to buy them, Tuitele said.

“Consumers choose organic because they want to avoid chemicals in their food and known carcinogens,” Tuitele said.

The sale of organic fruits and vegetables has grown rapidly in the United States in recent years, reaching $12.4 billion in 2011, or 12 percent of all fruit and vegetable sales, according to the Organic Trade Association. That’s up from $10.6 billion in sales in 2010, according to the Organic Trade Association in Washington, D.C.

In total, the organic industry grew to more than $28.6 billion in 2010, the most recent period for which statistics are available, according to the Organic Trade Association.