Estimation of Micronutrient Contents in Traditional Green Leafy Vegetables and Their Potential Contribution to Dietary Recommended Intakes

Micronutrient deficiency is a public health problem even though vegetable consumption could avert it. Vitamin C [Ascorbic acid (AA) and dehydroascorbate (DHAA)], β-carotene, lutein and vitamin B9 contents in seven traditional green leafy vegetables (raw and cooked) from Ghana were determined, to identify good sources and their potential contribution to Dietary Recommended Intakes. The micronutrients were quantified using spectrofluorimetric and HPLC/DAD analytical systems. Vitamin C content of samples ranged between 7.2 and 161 mg/100 g fresh weight. β-carotene content was within the ranges of 2.97 to 10.35 mg/100 g, Lutein 13.5 to 31.6 mg/100 g and total folate 18 to 146 μg /100 g. Lutein and β-carotene were in variable relative proportions (L/C from 1.6 to 6); Solanum macrocarpon and Amaranthus hybridus samples were particularly rich in lutein and β-carotene, respectively. Losses between 45 and 94% were observed for vitamin C, between 15 to 81% for β-carotene with the exception of an increase in Solanum macrocarpon and 17 to 80% for lutein under boiling. Similar drastic losses were recorded in microwaved samples; however, losses in lutein and folate were comparatively lower. The traditional green leafy vegetables studied were found to be very rich in the studied micronutrients, but cooking led to considerable losses. However, the cooked vegetables represent non-negligible sources of folate, good source of lutein and could provide up to 97% and 90% vitamin A and C Recommended Dietary Intakes respectively, when a 100 g is consumed. Improved cooking methods over the traditional methods of preparation are essential for retaining more micronutrients, for the benefit of consumers.

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