Lettuce is the second-most consumed vegetable in the U.S. Other vegetables may have a higher content of potentially healthful phytochemicals, but are consumed in much lower amounts. Thus, lettuce serves as a significant source for several vitamins and phytochemicals in the American diet. A surprisingly large amount of variation in vitamins and potentially healthful phytochemicals exists among and within lettuce types. This fact suggests that the nutritional profile of lettuce can be improved through breeding approaches. To that end we have mapped quantitative trait loci (QTL) and expression level polymorphisms (eQTL) to identify genes in metabolic pathways that appear to be involved in controlling the content of specific phytochemicals that may have positive effects on human health.