Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Food Science and Human Nutrition


Nutritional Sciences

First Advisor

Wendy S. White


Vitamin A deficiency remains prevalent in South Asia and sub-Saharan Africa. The well-established vitamin A supplementation program in children virtually reduces xerophthalmia and mortality in children but offers only a transient impact on raising serum retinol. Regular consumption of vitamin A-fortified food is considered a sustainable approach to maintain a healthy serum response of retinol of vulnerable populations. Bananas dominate the diet of many East-African countries where vitamin A deficiency is prevalent, thus making it a great vehicle for biofortification, a breeding technique to improve vitamin A value in the crop and increase dietary intake of vitamin A. Currently, provitamin A carotenoid (α- and β-carotene) biofortified bananas are being developed through genetic modification but its bioefficacy in humans has not been studied. The dominant provitamin A found in the biofortified bananas is α-carotene, followed by β-carotene. The nonsymmetrical α-carotene provides a molecule of active vitamin A (retinol) and its inactive analog (α-retinol). Exclusion of the inactive α-retinol with limited vitamin A activity is important for accurate determination of vitamin A activity of α-carotene in α-carotene containing foods such as provitamin A biofortified bananas. The overall objective of this study was to accurately determine the bioconversion factor of the α-carotene-containing provitamin A biofortified bananas in humans after the consumption of provitamin A biofortified bananas. An ultra-high selective and sensitive high-performance liquid chromatography–quadrupole-time-of-flight–high-resolution mass spectrometric with electrospray ionization in positive mode (HPLC-ESI (+)-QTOF-HRMS) quantitative method was developed and applied to the measurement of the postprandial appearance of provitamin A carotenoids and their retinyl ester bioconversion products as well as α-retinyl palmitate product of α-carotene after the consumption of provitamin A biofortified bananas. A 3µm C30 carotenoid column was used to separate α- and β-carotene, and their respective retinyl ester bioconversion derivative of α-retinol and retinol (i.e., α-retinyl ester and retinyl ester) in postprandial plasma triacylglycerol-rich lipoproteins. Labeled internal standards (d8-α-retinyl palmitate, 13C10-β-carotene, 13C10-retinyl palmitate) were used to account for analysis variability. Twelve healthy women each consumed three 200-g cooked banana fruit as follows: 1) biofortified banana fruit containing 1415.3 µg (2.64 µmol) of total β-carotene equivalents, 2) wild-type banana fruit with a β-carotene reference dose containing 536.8 μg (1.00 μmol) added β-carotene, and 3) wild-type banana fruit with a vitamin A reference dose containing 262.5 μg retinol activity equivalents (0.92 μmol) added retinyl palmitate. Mean (±SD) areas under the curve for retinyl palmitate in the TRL fractions (nmol·h) were 67.2 ± 50.5, 167.3 ± 114.5, and 167.8 ± 111.5 after consumption of the provitamin A-biofortified banana fruit, the wild-type banana fruit with the β-carotene reference dose, and the wild-type banana fruit with the vitamin A reference dose, respectively. The vitamin A equivalence of provitamin A of biofortified bananas and of wild-type banana fruit with the β-carotene reference dose were 18.52 ± 10.9 µg (mean ± SD) and 2.29 ± 0.93 µg, respectively. The vitamin A equivalency of provitamin A carotenoid biofortified banana fruit was similar to that reported for carotenoid-rich vegetables such as carrots or spinach, but less than that reported for starchy matrices (e.g., cassava, maize and rice).


Copyright Owner

SiewDin Sun



File Format


File Size

140 pages

Available for download on Saturday, January 07, 2023