(Beyond Pesticides, November 4, 2010) A new study finds that organically grown onions, carrots, and potatoes generally have no higher levels of antioxidants and related substances than vegetables grown with traditional fertilizers and pesticides, disputing other studies and failing to examine pesticide residues or other essential vitamin content. The study also does not consider the environmental and health impacts of conventional, chemical-based production systems. Researchers analyzed antioxidants termed “polyphenols” from onions, carrots and potatoes grown using conventional and organic methods and found no differences in polyphenol content for organic vs. traditional methods of growth. The study, “Effects of Organic and Conventional Growth Systems on the Content of Flavonoids in Onions and Phenolic Acids in Carrots and Potatoes” was published in the American Chemical Society’s bi-weekly Journal of Agricultural and Food Chemistry.
In this study, onions, carrots, and potatoes were cultivated in two-year field trials in three different geographical locations, comprising one conventional and two organic agricultural systems. The contents of two kinds of polyphenols, flavonoids and phenolic acids in plants were analyzed by pressurized liquid extraction and high-performance liquid chromatographyâˆ’ultraviolet quantification. Polyphenols have one or more phenol units in their chemical structure and are a group of secondary plant metabolites. According to researchers, though secondary plant metabolites are nonessential to humans, some of them have been proposed to have positive health effects including a decreased risk of heart diseases, dementia, and cancer. The content of polyphenols in plants is affected by factors such as cultivar, pathogen infection and pest attack, time of harvest, and storage and processing procedures. The content of nutrients and secondary plant metabolites in food products is also affected by, for example, growth conditions, use of fertilizers, climate, and plant nutrient availability.
Despite the fact that this study only looks at polyphenol content, some news outlets have been quick to use this as evidence that there is absolutely no difference between organic and conventional. This is not true, in fact; Dr. Pia Knuthsen and colleagues point out in the study that there are still many reasons to pay a premium for organic food products. They state that the most important reasons for the popularity of organic food products include improved animal welfare, environmental protection, better taste, and possible health benefits. The health benefits of organic food need to be approached on a broader level than just individual nutritional quality of each food item.
The researchers state that the potential health benefits of organic food consumption are still controversial and not considered scientifically well documented, however they fail to cite a recent study that found that organically produced strawberries had higher antioxidant activity, longer shelf life, and fared better in taste tests than conventional berries. Soils on the organic farms are also found to be healthier with higher organic matter concentration, and greater microbial biodiversity.
As organic agriculture continues to grow and evolve, efforts like this and media reports may mislead and impede the progress and promise of organic of the benefits. The benefits of organic agriculture are by no means limited to consumers. On conventional farms, dangerous pesticide use is a hazard to farmworkers, wildlife including endangered animals, as well as the water supply, and people, especially children living in the area. For more information on the importance of eating organic food for you, workers and the environment, check out Beyond Pesticides’ Eating with a Conscience food guide and organic food program pages.