Characterization of Provitamin A Status and Distribution in Commercial Grown Maize Varieties in Tanzania

Abstract

Provitamin A carotenoids are important as precursors for vitamin A, essential for stronger immune system and eyesight. Consumption of a plant-based diet rich in provitamin A such as provitamin A maize is an easy and affordable source of vitamin A. The majority of the commercially grown maize varieties in Tanzania are white whose provitamin A status is uncertain and undocumented. The existing current information suggests that white maize varieties have low provitamin A, an active form of vitamin A, thus putting maize consumers at risk of vitamin A deficiency (VAD). Characterization of provitamin A status in commercial maize varieties grown and consumed in Tanzania is important to provide baseline information required for vitamin A rich-maize improvement programs. Therefore, this study was conducted to map the status of provitamin A in commercial maize varieties to accrue the information needed to improve maize nutrition quality toward controlling VAD in the country. The study involved 14 maize varieties including commercial yellow and white pigmented maize from 3 regions of Tanzania. From maize samples, carotenoid extraction was conducted based on a protocol adapted from Kurilich and Juvik (1999). The concentration of beta carotene (BC), beta-cryptoxanthin (BCX), alpha-carotene (AC) were determined by an ultraviolet spectrophotometer and provitamin A computed for the individual carotenoids components. The study found that the concentration of provitamin A and associated carotenoids significantly differed (p<0.001) among varieties studied. The mean concentration (in μg/g) for provitamin A and its components in range as provitamin A (2.64-6.50), BC (1.91-4.66), BCX (0.649-1.21), and AC (0.819-1.46). The concentrations of provitamin A in the studied maize varieties were below the recommended levels (15 μg/g).  The low concentrations of provitamin A among commercial maize varieties signify the