A study of the relative nutrition of organic and conventional tomatoes was conducted by UC Davis Food Science professor Alyson Mitchell. The study compared the dried tomato samples from the Russell Ranch archives over a 10 year period and found significant differences in flavonoid content.
Flavonoids, secondary plant metabolites, may impact human health by reducing cardiovascular and other chronic diseases. The three main flavonoids in tomatoes (quercetin, kaempferol, and naringenin) were measured in the organic and conventional tomato/maize systems. Flavonoid content is greater in organic than conventional tomatoes and the differences have increased with time (Mitchell et al., 2007). Increases in flavonoid content appear to be correlated with lower amounts of organic nitrogen applied in the last six years to plots at LTRAS compared to the first six years. These results suggest that over-fertilization could reduce flavonoid content and health benefits of tomatoes.