Background and methodology
Fruit and vegetable intake reduces the risks for several chronic diseases in humans. Phytochemicals, and in particular, phenolic compounds, present in plant foods may be partly responsible for these health benefits through a variety of mechanisms. Since environmental factors play a role in a plant's production of secondary metabolites, it was hypothesized that an organic agricultural production system would increase phenolic levels. Cultivars of leaf lettuce, collards and pac choi were grown on organically certified plots and on adjacent conventional plots. Nine prominent phenolic agents were quantified by high-performance liquid chromatography (HPLC), including phenolic acids (e.g. caffeic acid and gallic acid) and aglycone or glycoside flavonoids (e.g. apigenin, kaempferol, luteolin, and quercetin).
Statistically, this study did not find significant higher levels of phenolic agents in lettuce and collard samples grown organically. The total phenolic content of organic pac choi samples as measured by the Folin- Ciocalteu assay, however, was significantly higher than conventional samples, and seemed to be associated with a greater attack of the plants in organic plots by flea beetles. These results indicated that although organic production method alone did not enhance biosynthesis of phytochemicals in lettuce and collards, the organic system provided an increased opportunity for insect attack, resulting in a higher level of total phenolic agents in pac choi.
Young, J. E., Zhao, X., Carey, E. E., Welti, R., Yang, S., & Wang, W. (2005). Phytochemical phenolics in organically grown vegetables. Journal of Molecular Nutrition & Food Research 49, 1136 �1142. Available on-line at: http://www3.interscience.wiley.com/cgi-bin/fulltext/112151791/PDFSTART.