Fermentation of Cassava Leaves Improves Provitamin A Carotenoid Bioefficacy in Mongolian gerbils (Meriones unguculatus)

Aims: The aim of this study was to evaluate the effect of fermented cassava leaves used as diet on provitamin A carotenoid bioefficacy. Study Design: Carotenoid analysis of fermented (F) and non-fermented (NF) cassava leaves, feeding Mongolian gerbils with F and NF leaves and β-carotene bioconversion evaluation. Place and Duration of Study: Felix Houphouet-Boigny University, Abidjan (March to August 2015) and University of Wisconsin-Madison, USA (March to June 2016). Methodology: Fermented cassava leaves were fed to Mongolian gerbils (Meriones unguculatus) and compared with non-fermented leaves and controls. Gerbils (32 days old, n = 46) were vitamin A (VA)-depleted for 3 weeks. After depletion, baseline gerbils (n = 6) were killed and remaining gerbils (n = 40) were weight-matched to 4 groups (n = 10/group) in the following treatments: VA-free feed (VA-); non-fermented leaves (NF); fermented leaves (F); and VA-free feed with daily oral doses of retinyl acetate dissolved in oil (VA+). The feeds were prepared using F and NF leaves at 3.53 and 4.27%, respectively, to equalise daily theoretical VA intake at 35 nmol β-carotene/g feed. Serum and livers were analysed using UPLC®. Results: The daily feed intake from the F and NF groups did not differ (4.38 ± 0.40 g). Serum retinol concentrations did not differ among groups, but the VA+ group had higher liver retinol (1.39 ± 0.32 μmol/liver) than the F and NF groups (P < 0.05). The calculated bioconversion factors were 13 and 37 µg β-carotene equivalents to 1 µg retinol for the F and NF groups, respectively. Conclusion: This study showed that the provitamin A carotenoids from small quantities of F and NF leaves were effective at maintaining VA status of gerbils when assessed by liver stores.

Determination of the Vitamin A Status and Body Pool Size of Ghanaian Infants Given Fortified Home Based Complementary Foods.

Objectives: Vitamin A deficiency is a public health problem which can be addressed using micronutrient powders in single dose sachets known as “Sprinkles”. This food-based approach offers an alternative to high dose Vitamin A supplements given directly to young infants. This strategy was evaluated by assessing the Vitamin A body pool using deuterium or 13C-retinol as a tracer. The primary objective was to investigate the impact of Vitamin A home fortification on the infant’s Vitamin A pool size using stable 13C2-retinol as a tracer among children who receive Sprinkles with or without VA. The Vitamin A status of infants at baseline was assessed using the modified relative dose response (MRDR) test and the 13C-retinol dilution test at follow-up. Methods: This was a community-based study involving 93 infants aged 7-9 months and randomised to receive daily Sprinkles with or without Vitamin A. Mothers were instructed to mix a single sachet of Sprinkles with a small amount of food which was given to the child. Infants were followed for 5 months. Results: At baseline the mean ratio (95%CI) of MRDR for infants in the intervention group was 0.032 (0.025-0.038) compared to 0.031(0.024-0.038) in the control group (p =0.80). At end line the mean Vitamin A concentration of infants in the intervention and control group 304.711 µmol vs. 252.207 µmol respectively but difference was not statistically significant. Conclusions: The vitamin A status of the infants was found to be adequate and the study demonstrated the use of stable isotopes as tracers to quantitatively estimate total body stores.

Vitamin A Status Assessment Methods from Deficiency to Excess.

Objectives: Methods to assess vitamin A status of groups and populations were reviewed. Methods: Various vitamin A status indicators were aligned with the liver reserve concentration where they have the most usability to predict liver stores of vitamin A if a positive result is found with the test. Both human and animal studies were used to compare these variables. Results: Clinical signs only have utility when liver reserves are almost exhausted and serum retinol concentrations have utility in the zone of overt deficiency. Dose response tests offer a little more coverage, but they also lack utility when vitamin A reserves are above adequate and are not able to distinguish between an adequate, sub-toxic and toxic vitamin A status. As different countries continue or begin to add preformed vitamin A to a variety of foods in the process of fortification, indicators that work in the excessive to toxic range of liver reserves are needed. To date the only indicator, excluding liver biopsy, that has been validated in this range of liver reserves is the retinol isotope dilution test. Conclusions: Preformed retinyl esters are added to a variety of staple foods; provitamin A biofortified crops are currently being released in several countries; and vitamin A supplementation programs are still being distributed in many countries, especially to preschool children. The ability to assess population vitamin A status needs to move beyond serum retinol concentrations. Retinol isotope dilution tests, either using deuterium or 13C, are the only methods that span the entire liver reserve continuum.

Biofortified Orange Maize is as Efficacious as a Vitamin A Supplement in Zambian Children Even on the Background of High Liver Reserves of Vitamin A.

Objectives: The main objective of this study was to determine the vitamin A (VA) bioefficacy of high β-carotene, biofortified (orange) maize in Zambian preschool children. Methods: A randomized, placebo-controlled orange maize efficacy trial was conducted in rural Zambian children (n = 140, 71.5±6.9 months). The paired 13C-retinol isotope dilution test, the most sensitive indirect marker of VA status, was used to measure total body reserves (TBR) of VA before and after a 90-d intervention. Treatment arms were white maize with placebo oil (VA-), white maize with 400 μg (VA+), and orange maize with placebo oil (orange). Results: TBR of VA increased in the VA+ and orange groups (203±386 and 109±341 μmol, respectively) (P = 0.0034), and were different from the VA- group (-4.5±208 μmol) using nonparametric analysis. Medians were VA- 12.6, VA+ 97.8, orange 83.7 μmol. Baseline estimates of liver concentration were 1.13±0.41 μmol/g, with 59% >1 μmol/g, the current sub-toxicity cutoff; none were <0.1 μmol/g, the proposed cutoff for deficiency. The bioconversion factor was 10.4 μg β-carotene: 1 μg retinol using the middle three quintiles of change in TBR from each treatment group. Serum retinol concentrations did not respond (P = 0.16). Conclusions: Biofortified maize is a very effective VA source when consumed as a staple food and could avoid potential toxicity issues with preformed VA from supplementation or fortification programs as observed in this population. Stable isotope methodology should be used to elucidate VA status of various populations, and serum retinol should be used with caution in setting global health policy.