2The objective of this study was to evaluate mineral, vitamin C, phenolic and flavonoid concentrations and 27 antioxidant activity levels in 15 leafy Amaranthus species. Across species, the concentration ranges of Ca, 28 K, Mg, P and phenolics, and activity ranges of antioxidants in amaranth leaves were 1.5-3.5mg/g, 5.5-8.8 29 mg/g, 1.8-4.5 mg/g, 0.5-0.9 mg/g, 3.2-5.5 mg gallic acid equivalents/g, and 38-90 μmol Trolox 30 equivalents/g (all values on a fresh weight [FW] basis), respectively. Amaranthus acanthochiton had the 31 highest concentrations of Ca, Mg, Ni, Zn, and A. deflexus and A. viridis had the highest concentrations of 32 Fe. A serving of any of the Amaranthus leaves (1 cup; 30 g FW) would contribute from 13 to 34% of the 33 daily value (DV) of Mg (DV = 400 mg; as established by the US Food and Drug Administration), and up 34 to 68% of the DV of vitamin C (DV = 60 mg). In addition, A. acanthochiton would be considered a good 35 source of Ca, Mn and Mo (10%-19% of the DV), and an excellent source of Mg and vitamin C (20% or 36 more of the DV). Amaranth leafy vegetables should be promoted as a dietary source of essential nutrients 37 and health-beneficial compounds.38

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Less than 10% of the estimated average requirement (EAR) for iron and zinc is provided by consumption of storage roots of the staple crop cassava (Manihot esculenta Crantz) in West African human populations. We used genetic engineering to improve mineral micronutrient concentrations in cassava. Overexpression of the Arabidopsis thaliana vacuolar iron transporter VIT1 in cassava accumulated three- to seven-times-higher levels of iron in transgenic storage roots than nontransgenic controls in confined field trials in Puerto Rico. Plants engineered to coexpress a mutated A. thaliana iron transporter (IRT1) and A. thaliana ferritin (FER1) accumulated iron levels 7–18 times higher and zinc levels 3–10 times higher than those in nontransgenic controls in the field. Growth parameters and storage-root yields were unaffected by transgenic fortification in our field data. Measures of retention and bioaccessibility of iron and zinc in processed transgenic cassava indicated that IRT1 + FER1 plants could provide 40–50% of the EAR for iron and 60–70% of the EAR for zinc in 1- to 6-year-old children and nonlactating, nonpregnant West African women.

The green leafy vegetables Cnidoscolus aconitifolius and Crotalaria longirostrata are native to Mexico and Central America, while Solanum scabrum and Gynandropsis gynandra are native to Africa. They are consumed in both rural and urban areas in those places as a main food, food ingredient or traditional medicine. Currently, there is limited information about their nutritional and phytochemical composition. Therefore, mineral, vitamin C, phenolic and flavonoid concentration, and antioxidant activity were evaluated in multiple accessions of these leafy vegetables, and their mineral and vitamin C contribution per serving was calculated. The concentrations of Ca, K, Mg and P in these leafy vegetables were 0.82-2.32, 1.61-7.29, 0.61-1.48 and 0.27-1.44 mg/g fresh weight (FW), respectively. The flavonoid concentration in S. scabrum accessions was up to 1413 μg catechin equivalents/g FW, while the highest antioxidant activities were obtained in C. longirostrata accessions (52-60 μmol Trolox equivalents/g FW). According to guidelines established by the US Food and Drug Administration, a serving size (30 g FW) of C. longirostrata would be considered an excellent source of Mo (20 % or more of the daily value), and a serving of any of these green leafy vegetables would be an excellent source of vitamin C. Considering the importance of the minerals, phytochemicals and antioxidants in human health and their presence in these indigenous green leafy vegetables, efforts to promote their consumption should be implemented.

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