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Whether organic fruits, vegetables, and grains are healthier for you than conventional produce has long been the point of contention. Many argue it's a baseless claim, a marketing ploy to convince you to spend more money on higher-priced organic foods. Others point to nutritional benefits of natural fertilizers to the plants  — not to mention to people avoiding chemicals. Research has turned up mixed results, although one of the biggest studies, a Stanford University report published in late 2012, asserts that organically-grown crops offered no additional nutrients that regular crops didn't provide.

But now a large-scale review of earlier research turns the tables again. This analysis, published in the British Journal of Nutrition, finds that organic crops contain considerably more disease-fighting antioxidants than their conventional counterparts, which would logically mean that organic is better for you. The researchers also found that organic harbors lower levels of chemical pesticides and toxic heavy metals, some of which have been linked to health issues, than conventional crops. However, few have debated that issue, since organic growing methods eschew chemical pesticides and fertilizers because they can undermine soil quality and damage nearby ecosystems.

So what explains this review's findings when prior studies have shown that organic and conventional crops are, nutritionally speaking, the same? According to Charles Benbrook, coauthor of this review and a program leader at Washington State University's Center for Sustaining Agriculture, it could be a case of past researchers' bias. "Most of the past studies have in fact reported higher levels of antioxidants in organic food," he says. "Some research teams have dismissed the differences as unimportant compared to just consuming another daily serving of fruit or veggies. But that's like saying a 4-mile-per-hour increase in fuel efficiency is not important because switching from a gas guzzler to a Prius increases average miles per gallon by a factor of three."

Benbrook also offers an explanation for how an organic tomato, for instance, winds up with more antioxidants than a tomato grown using chemical pesticides and fertilizers. "Two factors make the antioxidant content higher in organic crops," he says. "First is the 'dilution effect.' Conventional crops are typically treated with extra nitrogen, which pushes them to grow fast and reach a large size. This increases sugar and moisture content, thereby diluting levels of antioxidant phytochemicals. Second, plants on organic farms largely have to fend for themselves against insects and diseases. Their response to these attacks is almost always triggered by production of a phytochemical with antioxidant activity."

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But at the end of the day, are the additional nutrient benefits of organic enough to warrant the usually higher price tag? Benbrook believes so. "Organic is certainly somewhat healthier, both nutritionally and in terms of pesticide residues and risk," he says. "However, if you have to choose between conventionally grown produce or none at all, you should definitely purchase and enjoy the conventional."