Bioavailability of Yellow Maize Carotenoids in Humans
Condition: Vitamin A Status
Study type: Interventional
Phase: Phase 1

Summary: 
      The study hypothesis is that high ß-C yellow maize can provide vitamin A efficiently.

      - list item one ß-C in yellow maize

      The study will use stable isotope labeled high ß-C yellow maize and vitamin A in a
      well-nourished population by utilizing stable isotope dilution techniques. In this project,
      deuterium labeled vitamin A that is derived from the labeled ß-C yellow maize will be traced
      after being eaten by a human subject. Eight men (> 40 years and < 70 y) who are healthy,
      non-smoking,body weight within 20% of standard weight for height (Metropolitan) and not
      having taken vitamin A or ß-C supplements within the last month will be recruited as
      volunteers. This study will last for 50 days during which at day 1, cooked labeled yellow
      maize paste (porridge) equal to a total of ~ 2 bowls cooked yellow maize (from 100 - 200 g
      dry weight) containing ~ 1 mg ß-C will be taken by each volunteer. On day 8, a labeled
      vitamin A (1 mg of 13C retinyl acetate) in oil dose will be used in evaluation of liver
      storage of vitamin A. Forty six blood samples (460 cc) will be taken during the study which
      will be analyzed for serum carotenoids and retinoids using HPLC and mass spectrometry
      techniques.

      The serum concentration and isotope ratio of ß-C and retinol will be determined. Serum
      enrichment curve following each oral dose will be studied. The area under the curve (AUC) of
      retinol-d4 and labeled retinol from the reference dose in serum samples will be determined
      and compared. The equivalence of a high ß-C corn meal to vitamin A will be calculated based
      on the isotope reference method to determine the efficiency of corn ß-C to provide vitamin A.
    

Detailed description: 
      - list item one ß-C in yellow maize

      Pro-vitamin A carotenoids in plants are a major and safe vitamin A source for a vast
      population in the world. Even though, ß-carotene (ß-C) in vegetables has been considered as a
      safe vitamin A source, it is essential to determine the efficiency of provitamin A
      carotenoids in plant conversion to vitamin A. However, the bioavailability of vitamin A and
      carotenoids from food matrices has not been well studied due to the unavailability of
      isotopically labeled foods that can be fed to humans.

      The main objective of this study is to investigate the bioavailability of ß-C in yellow maize
      and its bioconversion to retinol stored in the liver using stable isotope labeled high ß-C
      yellow maize and vitamin A in a well-nourished population by utilizing stable isotope
      dilution techniques. In this project, the deuterium labeled vitamin A that is derived from
      the labeled ß-C yellow maize will be traced after being eaten by a human subject. This will
      allow for quantitative determination of the vitamin A equivalence of high ß-C plant foods.

      Eight men (> 40 years and < 70 y) who are healthy, non-smoking adults must have their body
      weight within 20% of standard weight for height (Metropolitan) and not having taken vitamin A
      or ß-C supplements within the last month will be recruited as volunteers.

      This is a 50 day study during which dose 1, cooked labeled yellow maize paste (porridge)
      equal to a total of ~ 2 bowls cooked yellow maize (from 100 - 200 g dry weight) containing ~
      1 mg ß-C will be taken by each volunteer. On day 8, dose 2 will be used in evaluation of
      liver storage of vitamin A using 1 mg of 13C retinyl acetate. One blood sample (20 cc) will
      be drawn during the screening process. Forty six blood samples (460 cc) will be taken during
      the study which will be analyzed for serum carotenoids and retinoids using HPLC and mass
      spectrometry techniques. The serum concentration and isotope ratio of ß-C and retinol will be
      determined. Serum enrichment curve following each oral dose will be studied. The area under
      the curve (AUC) of retinol-d4 and labeled retinol from the reference dose in serum samples
      will be determined and compared. The equivalence of a high ß-C plant food supplement to a
      vitamin A dose will be calculated based on the isotope reference method.
    

Intervention name(s): corn beta-carotene
Intervention type(s): Dietary Supplement
Intervention description(s): yellow corn beta-carotene in a 1 mg level to be taken as corn porridge in one meal by volunteers
Other intervention name(s): staple food beta-carotene
Intervention MeSH terms: Beta Carotene; Carotenoids
Allocation: Non-Randomized
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: beta-carotene; yellow maize; vitamin A