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.