Histological effects of roselle (Hibiscus sabdariffa L.) calyx in diets of albino rats

Roselle (Hibiscus sabdariffa) calyx was fermented traditionally and by controlled method with pure strains of Aspergillus flavus and Saccharomyces cerevisiae isolated from the fermentation. The proximate composition revealed that the sample fermented traditionally had the highest protein content of 14.7±2.5%. There was a significant decrease (Pd≤0.05) in the antinutrient content (phytate and tannin) with a reduction of 1.21-1.79% in tannin and 488.8±3.7–752.4±7.5 mg/100 g in phytate. The unfermented sample had phytate 2143.6±0.8 mg/100 g and tannin 5.30±1.1% respectively. Wistar–albino rats were fed a standard commercial diet for 3 days before the feeding experiment and during 21 days the diets containing 60% unfermented and fermented calyx samples at the expense of maize in the basal diet. There was a decrease in growth of albino rats on all the treatments except for the control diet where there was increase in growth. Histopathological studies showed that in high doses roselle calyx could cause liver injury.