THE DETAILS: The comprehensive experiment, led by John Reganold, PhD, Washington State University Regents professor of soil science, controlled for three important variables: The soil was the same, the varieties of strawberries were the same, the weather was the same. Reganold and his team grew three varieties of strawberries on 13 organic and 13 conventional fields that were side by side, just 25 to 50 feet apart.
It's a significant addition to the body of scientific literature comparing organic and chemical growing methods, says Reganold. "There is no study that represents reality as well as this one does," he says. "What makes it so strong is that we have so much data." About 150 studies have been done comparing other fruits and vegetables, but most have been criticized because the sample was too small, or because there were too many variables that may have influenced the results. Of the 150 published studies, only about 10 are considered scientifically valid. Of those 10, eight favor organic; two show no difference.
In Reganold’s studies, published in the peer-reviewed online journal PLoS, the experiments were repeated over a two-year period, and the strawberries were handled just as if they were going to a retail location. The taste and nutritional quality of the three varieties of strawberries were analyzed, and so was the soil in which they grew.
The organic strawberries were smaller but denser. They had almost 10 percent more vitamin C, and were almost 9 percent higher in antioxidants, two important reasons for eating them, since strawberries have the most concentrated levels of vitamin C and antioxidants in the diet. The organic berries were also lower in potassium and phosphorous than the conventional berries, but that should not take away from their superiority, since strawberries are not a significant source of potassium. (The best sources of potassium are bananas, root vegetables, melons, peaches, and avocados.) As for phosphorus, many Americans—notably those of us who drink cola beverages—get too much phosphorus in our diets, and that can lead to bone loss.
More sweet news: The research also suggests that choosing the superior nutrition of organic strawberries doesn't mean sacrificing flavor. In a blind tasting by a consumer panel, tasters judged the organic version of one strawberry variety, Diamante, as better-tasting than the chemically grown version. For the other two varieties, there was little or no difference in taste reported. Finally, the organic berries had less post-harvest fungal rot, (even though no synthetic chemical fungicides were used on them), and spoiled more slowly.
The benefits of organic agriculture go beyond the fruits themselves. The study also looked at soil quality, an important consideration that those of us who buy most of our food in supermarkets don’t always think about. High-quality soil is the basis for a healthy ecosystem; in the study, the organic fields had much higher levels of nutrients, such as zinc, boron, sodium, and iron.
WHAT IT MEANS: While this study may not convince all the doubters, it's strong evidence that organic growing methods can produce nutritionally superior food. As Rodale.com reported earlier this year when a "report" (with no new information) cast doubt on the value of organic food, studies find that organic food is, on average, 25 percent more nutritious than food grown with agrichemicals. Which is not to say that organic comes out more nutritious for every type of crop.
But frankly, better nutrition is only one of the benefits of organic agriculture, and maybe not even the most important one. Using organic methods means not adding toxic pesticides to our food or our environment. Take methyl bromide, for example: It's a highly toxic fumigant. Its use has been an explosive issue in California, where 90 percent of strawberries are grown in this country. Methyl bromide was banned in the 1980s under an international treaty, but it's continued to be in use in the U.S. because scientists had not been able to create a less-toxic substitute. A proposed replacement, methyl iodide, is a known carcinogen linked to miscarriages and thyroid disease.
As the strawberry study also found, organic methods produce healthier soil. Pesticides kill not just pests, but also the beneficial organisms in the soil that help store carbon (a climate change solution), retain water (reducing runoff and flooding during storms and storing more water for times of drought), and keep plants healthy and more resilient against pests and diseases. About the only positive finding relating to the chemically grown strawberries in the study was a higher yield. But is that a good trade-off for less-nutritious fruit, depleted soil, and toxins in our water, soil, and food?
To find out why organic agriculture is important for everyone, see Why We All Need an Organic Manifesto.
For more reasons to buy organic, see The Double-O Dozen: 12 Reasons to Buy Only Organic.
For advice on saving money on organic food, see Don't Be Fooled By the Dirty Dozen.