Anne Bozack Quercetin Content in Spinach May 8 2006p. 1Effect of Organic and Conventional Farming Practices on Quercetin Content in Spinach,Spinacia oleraceaAnne BozackAbstract Positive stresses and limitations of nutrient accessibility inherent in organic systemsmay increase the biosynthesis of secondary metabolites relative to conventional systems. Sincemany secondary metabolites have antioxidant capabilities, the potential of agricultural conditionsto increase their content in produce has implications for the health of individual consumers. Inparticular, the common antioxidant quercetin, present in spinach, Spinacia oleracea, hasantihistamine and anti-tumor properties. Due to the beneficial properties of this compound, thisstudy was designed to establish the influence of 5 treatments associated with organic andconventional farming on its content in spinach: 1) organic soil, 2) synthetic soil (withsupplemental fertilizers), 3) synthetic pesticides, 4) simulated herbivory, and 5) syntheticherbicides. The content (mass per fresh weight) of quercetin and its glycocides rutin andquercitrin were quantified with high pressure liquid chromatography, HPLC. Rutin andquercitrin were not detectable in any of the samples. Quercetin was present with each of thetreatments; however, its content did not differ significantly among them.Anne Bozack Quercetin Content in Spinach May 8 2006p. 2IntroductionOver the twentieth century, trends in agriculture have shifted production from local andsmall-scale farms to global and corporate businesses. Favored by economics of scale, largeproduction systems have turned to chemical solutions to increase productivity and alleviateecological problems -- a praxis often upsetting natural systems through the use of syntheticinsecticides and herbicides (Francis 2004). Organic farming practices offer an alternativethrough the decreased use of chemical inputs. Consumers, driven by environmental and healthconcerns to select organic products, have encouraged this movement (Davies et al. 1995) andcaused the market to increase 40-fold between 1986 and 1996 (Fisher 1999).Organic policy varies throughout the world (Bourn and Prescott 2002), but generallyincludes a set of core regulations. The United States Department of Agriculture (USDA)requires certification to meet minimum standards prohibiting the use of nearly all chemicalpesticides and herbicides and mandating practices that improve soil condition and minimizeerosion (National Organic Program 2000). Studies have largely concluded that organic practicesoffer environmental benefits relative to conventional systems by increasing biodiversity,decreasing nutrient leaching (Hansen et al. 2001), and increasing nutrient recycling (Brandt andMølgaard 2001). However, implications for human health are more equivocal.Food Quality. Comprehensive reviews have reached some broad conclusions regardingfood quality, although differences in study design and the variability inherent in agriculturalsystems contribute to ambiguous findings that are often difficult to interpret (Benbrook 2005).Research suggests that relative to their conventionally-produced counterparts, organically-produced crops generally have lower nitrate levels (Bourn and Prescott 2002, Brandt andMølgaard 2001, Woese et al. 1997), higher dry matter content (Bourn and Prescott 2002, Woeseet al. 1997), and fewer chemical residues (Baker et al. 2002, Woese et al. 1997). Conclusionsregarding mineral content are more varied, with some studies stating no difference (Woese et al.1997) and others reporting significantly higher levels of certain minerals in organic produce(Bourn and Prescott 2002, Worthington 2001). Likewise, studies addressing Vitamin C contentreport contrasting findings, ranging from higher levels to no difference or lower levels (Bournand Prescott 2002, Woese et al. 1997).Secondary Metabolites. The growing field of research focusing on levels of secondarymetabolites may offer additional insights about food quality. Plants produce secondaryAnne Bozack Quercetin Content in Spinach May 8 2006p. 3metabolites primarily for defense; hence, many are stress-induced through wounding, pathogenicattack, exposure to high levels of ultraviolet light, the need for signaling, insufficient nutrients, orlow temperatures (Dixon and Palva 1995). Relative to conventional systems, organic systemsmay increase the exposure of crops to such stresses, thus inducing the synthesis of secondarymetabolites (Manach et al. 2004). Different cultivars display larger variation in secondarymetabolite levels than those attributed to cultivation methods (Brandt and Mølgaard. 2001)While crucial to plant health, some secondary metabolites like polyphenols and carotenoidsmay also offer benefits for humans by acting as antioxidants to prevent oxidative damage in cellsand subsequent cancerous growth (Benbrook 2005). Radical-scavenging acids and enzymes areproduced by the human body but dietary contributions augment the supply of antioxidants (Johns1999).Hindered by a variety of confounding factors, studies linking health benefits to specificchemicals are difficult (Brandt et al. 2004). However, some studies have associated polyphenolconsumption with a decrease in the occurrence of chronic diseases including cardiovasculardisease (Kenkt et al. 2002) most notably in women (Mennen et al. 2004, Arai et al. 2000), sometypes of cancer, asthma, and type 2 diabetes (Kenkt et al. 2002). Quercetin, the most abundantflavonoid in food (Formica and Regelson 1995), is highly studied and has been linked to severalhealth benefits attributed to its antihistamine (Middleton et al. 1981) and anti-tumor properties(Lamson and Brignall 2005, Lambert et al. 2005). Specifically, it has been associated withdecreased rates of prostate cancer (McCann et al. 2005), possibly due to its inhibition of enzymesresponsible for carcinogenesis (Chaudhary and Willett 2006). However, some animal modelshave shown no effect (Lambert et al. 2005).Akin to research regarding nutrient levels, findings comparing antioxidant levels inconventionally and organically-cultivated crops are variable and subject to
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