WASHINGTON: The debate over whether organic food is better for our health and worth its higher price keeps raging on in the United States as the conclusion of four decades of studies seems far from clear.

The controversy was back in the news last month when a large-scale study by researchers from Stanford University found organic foods no more nutritious than conventional products, though they did have fewer traces of pesticides.

Researchers, who reviewed 237 different studies, did not find organic meats were healthier either.

“When we began this project, we though that there would likely be some findings that would support the superiority of organic over conventional food,” said Dr Dena Bravata of Stanford University, lead author of the study.

“We were definitely surprised it's not the case.”

Researchers said they found conventional fruits and vegetables had more pesticide residues than their organic equivalents but that the trace pesticide levels were almost always within the range authorities allow.

In 2011, researchers at Britain's Newcastle University reached different conclusions when they did a meta-analysis of combined data from the same 237 studies, which were done over the course of four decades.

Their research, which did not generate much attention, found non-genetically modified and pesticide-free fruits and vegetables had better nutritional value: among the standout findings, that they contain more vitamin C than conventional fruits and vegetables.

And so the lack of decisive conclusions to be drawn led to an interesting development.

The American Academy of Pediatrics on Oct 22 announced that no scientific study had been proven organic foods to be healthier. It recommended in a report that children eat a wide variety of fruits and vegetables — whether they are organic or not.

“In the long term, there is currently no direct evidence that consuming an organic diet leads to improved health or lower risk of disease,” it said.

It was a potentially important idea, as many parents would like their children and especially babies to eat organic fruits and vegetables, but their high cost can be prohibitive for most. The market in organic foods is already worth $31 billion a year — and surging by 10% every year.

“We do not want families to choose to consume smaller amounts of more expensive organic foods and thus reduce their overall intake of healthy foods like produce,” Janet Silverstein of the American Academy of Pediatrics said last week.

“What's most important is that children eat a healthy diet rich in fruits, vegetables, whole grains, and low-fat or fat-free dairy products, whether those are conventional or organic foods,” she said. “This type of diet has proven health benefits.”

The report nonetheless found the studies indicated lower presence of trace pesticides in organic foods, while organic beef had fewer antibiotic resistant bacteria.

David Haytowitz, a nutritionist at the US Department of Agriculture, stressed that comparing organic and conventional products was complicated.

“It is very difficult to make a comparison because there are so many variables affecting the nutrient content of a crop...the growing location, the controlled practices etc.,” he stressed.

So “unless you do a peer study where you plant a particular crop organic and conventional side by side and be sure there is no cross contamination,” the comparison really is not a simple one.

David Schardt, chief nutritionist at the Center for Science in the Public Interest, however said that could be beside the point. In his view, Americans choose organic foods for a range of reasons.

“Most people who start eating organic food do so to avoid pesticide or other contaminants in the food,” Schardt told AFP.

That makes sense to Christine Bushway, head of the Organic Trade Association.

“Even though the pesticide and contaminants in conventional food remain technically at safe levels it still make sense for those families with kids or with expecting mothers to avoid them and ...choose organic,” he stressed.

“The (Stanford report) says organic food has 30% less pesticide and that is what the consumer is concerned about,” she said.