1Gibson, RS & Hotz, C (2001) Dietary diversification/modification strategies to enhance micronutrient content and bioavailability of diets in developing countries. Br J Nutr 85, S159–S166.
2West, KP Jr (2002) Extent of vitamin A deficiency among preschool children and women of reproductive age. J Nutr 132, 2857S–2866S.
3McLauren, DS & Frigg, M (2002) Sight and Life Manual. Practical Guide on Vitamin A in Health and Disease, pp. 1–72. Basel: Sight and Life Publication.
5Food and Agriculture Organization (1993) Preventing micronutrient deficiencies: food abundance and diversity are fundamental. Food Nutr Agric Bull 7, 8–17.
6Mieko, K & Rodriguez-Amaya, DB (2003) Carotenoid composition of hydroponic leafy vegetables. J Agric Food Chem 51, 2603–2607.
7Heinonen, MI, Ollilainen, V, Linkola, EK, et al. (1988) Carotenoids in Finnish foods: vegetables, fruits and berries. J Agric Food Chem 37, 655–659.
8Mercadante, AZ & Rodriguez-Amaya, DB (1991) Carotenoid composition of a leafy vegetable in relation to some agricultural variables. J Agric Food Chem 39, 1094–1097.
9Muller, H (1997) Determination of the carotenoid content in selected vegetables and fruit by HPLC and photodiode array detection. Z Lebensm Unters Forsch A 204, 88–94.
10EL-Qudah, JM (2009) Identification and quantification of major carotenoids in some vegetables. Am J Appl Sci 6, 492–497.
11Tanumihardjo, SA, Bouis, H, Hotz, C, et al. (2008) Biofortification of staple crops: an emerging strategy to combat hidden hunger. Comp Rev Food Sci Food Safety 7, 329–334.
12Tanumihardjo, SA (2008) Food-based approaches for ensuring adequate vitamin A nutrition. Comp Rev Food Sci Food Safety 7, 373–381.
13Riedl, J, Linseisen, J, Hoffmann, J, et al. (1999) Some dietary fibers reduce the absorption of carotenoids in women. J Nutr 129, 2170–2176.
14Brown, MJ, Ferruzzi, MG, Nguyen, ML, et al. (2004) Carotenoid bioavailability is higher from salads ingested with full-fat than with fat-reduced salad dressings as measured with electrochemical detection. Am J Clin Nutr 80, 396–403.
15Borel, P (2003) Factors affecting intestinal absorption of highly lipophilic food microconstituents (fat-soluble vitamins, carotenoids and phytosterols). Chem Lab Med 41, 979–994.
16Granado-Lorencio, F, Olmedilla-Alonso, B, Herrero-Barbudo, C, et al. (2007) Comparative in vitro bioaccessibility of carotenoids from relevant contributors to carotenoid intake. J Agric Food Chem 55, 6387–6394.
17Pasquier, B, Armand, M, Castelain, C, et al. (1996) Emulsification and lipolysis of triacylglycerols are altered by viscous soluble dietary fibres in acidic gastric medium in vitro. Biochem J 314, 269–275.
18van Het Hof, KH, West, CE, Weststrate, JA, et al. (2000) Dietary factors that affect the bioavailability of carotenoids. J Nutr 130, 503–506.
19Lee, CM, Lederman, JD, Hofmann, NE, et al. (1998) The Mongolian gerbil (Meriones unguiculatus) is an appropriate animal model for evaluation of the conversion of β-carotene to vitamin A. J Nutr 128, 280–286.
20Tontisrin, K, Nantel, G & Bhattacharjee, L (2002) Food-based strategies to meet the challenges of micronutrient malnutrition in the developing world. Proc Nutr Soc 61, 243–245.
21Reeves, PG, Forrest, HN & Fahey, GC Jr (1993) AIN 93 purified diets for laboratory rodents: final report of the American Institute of Nutrition ad hoc writing committee on the reformulation of the AIN76A rodent diet. J Nutr 123, 939–951.
22Association of Official Analytical Chemists (1997) Official Methods of Analysis, 16th ed. Washington, DC: AOAC.
23Howe, JA & Tanumihardjo, SA (2006) Carotenoid-biofortified maize maintains adequate vitamin A status in Mongolian gerbils. J Nutr 136, 2562–2567.
24Valentine, AR & Tanumihardjo, SA (2004) Adjustments to the modified relative dose response test for assessment of vitamin A status minimize the blood volume used in piglets. J Nutr 134, 1186–1192.
25Tanumihardjo, SA & Howe, JA (2005) Twice the amount of α-carotene isolated from carrots is as effective as β-carotene in maintaining the vitamin A status of Mongolian gerbils. J Nutr 135, 2622–2626.
26Asson-Batres, MA, Smith, WB & Clark, G (2009) Retinoic acid is present in the postnatal rat olfactory organ and persists in vitamin A-depleted neural tissue. J Nutr 139, 1067–1072.
27Mills, JP, Terasawa, E & Tanumihardjo, SA (2007) Excessive preformed vitamin A intake by mothers amplifies early fetal liver retinyl ester storage in captive Old World monkeys. Comp Med 57, 505–511.
28Akwaowo, EU, Ndon, BA & Etuk, EU (2000) Minerals and antinutrients in fluted pumpkin (Telfairia occidentalis Hook F.). Food Chem 70, 235–240.
29Antia, BS, Akpan, EJ, Okon, PA, et al. (2006) Nutritive and anti-nutritive evaluation of sweet potatoes (Ipomoea batatas) leaves. Pak J Nutr 5, 166–168.
30Ejoh, RA, Djuikwo, VN, Gouado, I, et al. (2007) Effect of the method of processing and preservation on some quality parameters of three non-conventional leafy vegetables. Pak J Nutr 6, 128–133.
31Oduro, I, Ellis, WO & Owusu, D (2008) Nutritional potential of two leafy vegetables: Moringa oleifera and Ipomoea batatas leaves. Scient Res Essay 3, 57–60.
32Bhaskarachary, K, Rao, DSS, Deosthale, YG, et al. (1995) Carotene content of some common and less familiar foods of plant origin. Food Chem 54, 189–193.
33Speek, AJ, Speek-Saichua, S & Schreurs, WHP (1988) Total carotenoid and β-carotene contents of Thai vegetables and the effect of processing. Food Chem 27, 245–257.
34Tee, E-S & Lim, C-L (1991) Carotenoid composition and content of Malaysian vegetables and fruits by the AOAC and HPLC methods. Food Chem 41, 309–339.
35Ryan, L, O'Connell, O, O'Sullivan, L, et al. (2008) Micellarisation of carotenoids from raw and cooked vegetables. Plant Foods Hum Nutr 63, 127–133.
36Chen, BH & Chen, YY (1992) Determination of carotenoids and chlorophylls in water convolvulus (Ipomea aquatica) by liquid chromatography. Food Chem 45, 129–134.
37Aman, R, Schieber, A & Carle, R (2005) Effects of heating and illumination on trans–cis isomerization and degradation of β-carotene and lutein in isolated spinach chloroplasts. J Agric Food Chem 53, 9512–9518.
38Rock, CL, Lovalvo, JL, Emenhiser, C, et al. (1998) Bioavailability of β-carotene is lower in raw than processed carrots and spinach in women. J Nutr 128, 913–916.
39Thakkar, SK, Maziya-Dixon, B, Dixon, AGO, et al. (2007) Carotene micellarization during in vitro digestion and uptake by Caco-2 cells is directly proportional to β-carotene content in different genotypes of cassava. J Nutr 137, 2229–2233.
40Olson, JA (1984) Serum levels of vitamin A and carotenoids as reflectors of nutritional status. J Natl Cancer Inst 73, 1439–1444.
41Howe, JA, Maziya-Dixon, B & Tanumihardjo, SA (2009) Cassava with enhanced β-carotene maintains adequate vitamin A status in Mongolian gerbils (Meriones unguiculatus) despite substantial cis-isomer content. Br J Nutr 102, 342–349.
42Davis, C, Jing, H, Howe, JA, et al. (2008) β-Cryptoxanthin from supplements or carotenoid-enhanced maize maintains liver vitamin A in Mongolian gerbils (Meriones unguiculatus) better than or equal to β-carotene supplements. Br J Nutr 100, 786–793.
43Van Lieshout, M, West, CE, Muhilal, , et al. (2001) Bioefficacy of β-carotene dissolved in oil studied in children in Indonesia. Am J Clin Nutr 73, 949–958.
44Dosti, MP, Mills, JP, Simon, PW, et al. (2006) Bioavailability of β-carotene (βC) from purple carrots is the same as typical orange carrots while high βC carrots increase βC stores in Mongolian gerbils (Meriones unguiculatus). Br J Nutr 96, 258–267.
45Pollack, J, Campbell, JM, Potter, SM, et al. (1994) Mongolian gerbils (Meriones unguiculatus) absorb beta-carotene intact from a test meal. J Nutr 124, 869–873.
46Takyi, EEK (1999) Children's consumption of dark green, leafy vegetables with added fat enhances serum retinol. J Nutr 129, 1549–1554.
47Tchum, SK, Newton, S, Tanumihardjo, SA, et al. (2009) Evaluation of a green leafy vegetable intervention in Ghanaian postpartum mothers. Afr J Food Agric Nutr Develop 9, 1294–1308.
48Jalal, F, Nesheim, MC, Agus, Z, et al. (1998) Serum retinol concentrations are affected by food sources of β-carotene, fat intake, and anthelmintic drug treatment. Am J Clin Nutr 68, 623–629.
49van Jaarsveld, PJ, Faber, M, Tanumihardjo, SA, et al. (2005) β-carotene-rich orange-fleshed sweet potato improves the vitamin A status of primary school children assessed with the modified-relative-dose–response test. Am J Clin Nutr 81, 1080–1087.
50De Pee, S, West, CE, Muhilal, , et al. (1995) Lack of improvement in vitamin A status with increased consumption of dark-green leafy vegetables. Lancet 346, 75–81.
51Brown, ED, Micozzi, MS, Craft, NE, et al. (1989) Plasma carotenoids in normal men after a single ingestion of vegetables or purified β-carotene. Am J Clin Nutr 49, 1258–1265.
52Micozzi, MS, Brown, ED, Edwards, BK, et al. (1992) Plasma carotenoid response to chronic intake of selected foods and β-carotene supplements in men. Am J Clin Nutr 55, 1120–1125.
53Törrönen, R, Lehmusaho, M, Häkkinen, S, et al. (1996) Serum β-carotene response to supplementation with raw carrots, carrot juice or purified β-carotene in healthy non-smoking women. Nutr Res 16, 565–575.
54Thurnham, DI (2007) Bioequivalence of β-carotene and retinol. J Sci Food Agric 87, 13–39.