Joanna Cosgrove10.01.08
Organic—Not Healthier?
Study argues pricier organic fare isn’t nutritionally superior.
By
Joanna Cosgrove
Online Editor
The study, published in a recent issue of the Society of Chemical Industry’s (SCI) Journal of the Science of Food and Agriculture, investigated the effect of three different model cultivation systems on selected major and trace element contents of dried foodstuffs—carrots, kale, peas, potatoes and apples—grown in two consecutive years, as well as mineral retention determined in 36 rats (second generation in a multi-generation study) fed diets based on these foodstuffs from one year.
The study conclusion did “not support the belief that organically grown foodstuffs generally contain more major and trace elements than conventionally grown foodstuffs,” nor did it appear to “be an effect on the bioavailability of major and trace minerals in rats.”
Furthermore, there was “no evident trend towards differences in element content of foodstuffs or diets due to the use of different cultivation systems, and differences between harvest years exceeded those seen between cultivation methods. Also, no significant differences in the retention of elements in rats fed diets derived from different cultivation systems were seen, since higher intake resulted in correspondingly higher excretion.”
“No systematic differences between cultivation systems representing organic and conventional production methods were found across the five crops so the study does not support the belief that organically grown foodstuffs generally contain more major and trace elements than conventionally grown foodstuffs,” explained Susanne Bügel, PhD, lead researcher and associate professor, Department of Human Nutrition and Centre for Advanced Food Studies, Faculty of Life Sciences, University of Copenhagen.
Dr. Bügel conceded that organic foods’ lack of pesticides might imbue certain health beneficial effects, but said there’s a real need to develop scientifically sound biomarkers capable of measuring such differences. “Research in the field is ongoing and my hope is that in a couple of years we might be able to do a long-term human study that might give some answers as to the health benefits or lack of same if changing from conventional to organic food,” she said.
Industry Backlash
Needless to say, the study’s results did not sit well with proponents of organic fare. Dr. Charles Benbrook, chief scientist, The Organic Center, Enterprise, OR, and his colleagues have conducted an extensive review of comparative studies between organic and conventional foods. In the August issue of The Scoop, The Organic Center’s newsletter, Dr. Benbrook rebuked the Danish study.
“The Danish research team compared the retention of nutrients in rats fed a diet composed of organic and conventional dried fruits and vegetables. Only trace mineral levels were compared; no results were reported on vitamins, polyphenols, and antioxidants (nutrients that routinely are present at higher concentrations in organic food),” he wrote.
Laura Batcha, director, marketing and public relations, Organic Trade Association, agreed and noted that several studies have emerged demonstrating that organically grown foods are as, if not more, nutrient dense as their conventionally grown counterparts. “For example, research conducted at the US Department of Agriculture and Rutgers University in New Jersey found that organic blueberries contain ‘significantly higher’ levels of fructose, glucose, and ORAC (Oxygen Radical Absorbance Capacity, a method of measuring antioxidant capacities of foods) than conventionally grown blueberries,” she said. “Other research, conducted at Washington State University, found that various organic juices contained higher levels of antioxidants than their conventional equivalents. Still other research, published in the June 23, 2007 issue of the Journal of Agricultural and Food Chemistry, revealed that tomatoes grown organically contained nearly twice the amount of health-promoting flavonoids than those that were grown conventionally.”
Dr. Benbrook also thought the Danish study encouraged misrepresentation by the media. “No differences were found in nutrient levels, leading the authors to suggest that such findings might dampen consumer demand for organic food,” he wrote. “Some media outlets have picked up this finding, and have dramatically broadened it to support headlines and statements like ‘Organic food no more nutritious than conventional.’ A review of the study’s experimental design, however, raises serious questions about whether this study’s results actually support even the more narrow mineral-based conclusions stated by the authors.”
The study’s methodology was another bone of contention. “The team grew one-half the fruits and vegetables in both the ‘conventional’ and organic plots on soils that were previously managed organically. Accordingly, this portion of the conventional crops fed to the rats benefited from all the nutrient-enhancing and plant-health benefits of heightened soil quality from prior organic soil management,” he wrote. “Given the series of studies published in the U.S. in the last three years pointing to soil quality enhancement in organic systems as the major cause, or explanation of observed differences in nutritional quality, it is not surprising that this Danish study found no statistically significant difference in mineral levels in the organic and ‘conventional’ crops that were harvested and fed to the rats.
“In addition,” he continued, “the organic plots were grown under limited nitrogen, whereas the conventional crop was not. On the basis of the criteria the Center developed to judge the scientific validity of comparison studies, and used in completing our March 2008 report on the nutrient content of organic food, http://www.organic-center.org/science.nutri.php?action=view&report_id=126, this Danish study is clearly ‘invalid’ for purposes of comparing the nutrient content of conventional and organic foods.”
Dr. Benbrook concluded that although the study “was carefully conducted and valid for testing the impacts of the production conditions embedded in its experimental design … by virtue of this design, little weight should be placed on its findings in terms of the differences in conventional and organic management on crop nutritional quality.”
Ms. Batcha expressed concerned about the study’s divisive lack of regard for the health benefits associated with not consuming pesticides and asserted that the value of organic agricultural methods can and should be measured in a variety of ways. “By supporting a system of sustainable agricultural management that promotes soil health and fertility through the use of such methods as crop rotation and cover cropping, organic nourishes plants, fosters species diversity, helps combat climate change, prevents damage to valuable water resources, and protects farmers and farmers’ families from exposure to harmful chemicals,” she said. “In this sense, the value of organic reflects both understanding and commitment: understanding that personal and environmental health are inseparable, and commitment to the bigger, more complex picture of which our personal health is a part.”