Organic strawberries given a thumbs up in WSU study

Organic produce has more nutrients than conventionally grown, according to a Washington State University study published Wednesday.

The research, focused on strawberries, likely won't end the debate over organic nutrition, though.

Last year, a major British study — one that looked at 50 years of research on a plethora of foods — concluded that organic is no more nutritious than conventional.

What's a berry lover to do?

John Reganold, a soil scientist at WSU and lead author of the recent study, said he's betting on the organic foods.

"Even though the jury's out, it's starting to lean toward organic," he said.

His study, published in the online journal PLoS ONE, found the organic strawberries not only more nutritious, but they left the soil healthier and had longer shelf life, too.

The study, billed as the most comprehensive of its kind, examined berries from 26 commercial operations in California.

For each organic field, researchers identified a nearby conventional field with the same soil, growing the same strawberry variety, and that was planted at about the same time. The study period spanned two years. Researchers sampled berries in the spring, summer and fall.

In tests, the organic strawberries had significant concentrations of antioxidants and vitamin C, according to the study.

The conventional berries, however, had higher concentrations of potassium, although the levels were still low because berries are not a major source for the mineral anyway.

Shelf life

Researchers also studied shelf life and found that the organic fruit lasted about a half-day longer than conventional. That surprised Reganold, who surmised that the chemicals used on conventional fruit would better keep mold at bay.

"When you start getting data like that, and it involves multiple varieties, multiple sampling times and multiple farms, it's kind of like, wow," he said.

The organically farmed soil also contained more nutrients and organic matter than the conventional plots.

Reganold said it's already pretty clear that conventional berries contain higher levels of pesticides, so they didn't test for that. Nor did they measure yield.

The project was funded by the federal government and The Organic Center, which advocates for organic food and is supported by major organic companies.

In the London study, conducted by the national school of public health, researchers reviewed hundreds of nutritional studies, throwing out those whose methodology was deemed scientifically unsound.

It found "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 found similar results in comparing meats. Any nutritional differences they did find were not significant, the researchers said.

The study was funded by the Food Standards Agency, an independently operated British government group "set up to protect the public's health and consumer interests."

How to explain the difference between the results?

Reganold did not dispute the other findings, but he pointed out that over the last decade there have been at least 10 review studies like the London one, and eight came down on the side of organics.

"We didn't have any preconception" going in, he said.

He cautions, though, against extrapolating the WSU nutrition results to other kinds of produce.

In the meantime, having eaten hundreds and hundreds of strawberries during the study, he still isn't sick of them.

"Oh, God, no," he said.

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