Environmental and Genetic Variation in Essential Mineral Nutrients and Nutritional Value Among Brassica Vegetables

Dietary minerals play an important role in human nutrition and proper metabolism. We grew various Brassica crops under field conditions in 2012 and 2013 and analyzed 8 essential minerals from edible tissues of those crops. Among the investigated crops, pak choi (Brassica rapa), mustard greens (B. juncea; B. nigra), and komatsuna (B. rapa) were generally high in most minerals, according to dry weight-based concentrations. The percentage recommended daily intake (RDA) or adequate intake (AI) values, calculated using fresh weight-based concentrations, suggest that Brassica vegetables are a good source of iron, calcium, and manganese, providing > 20% of %RDA/AI depending on crop. Kale (B. oleracea; B. napus) was generally higher in %RDA/AI, in particular for calcium (Ca), phosphorous (P), magnesium (Mg), and manganese (Mn). From the 2-year study, days to harvest, growing degree days, total solar radiation, and total precipitation and evaporation were found to affect the concentration of Ca, P, Ma, and Me. The results of this study provide a direct comparison of the mineral composition of various Brassica crops grown under the same conditions and will help consumers’ food choice for better nutritional value.