(P16-011-23) Iron Bioavailability of Biofortified Cowpea (Vigna unguiculata L. Walph) Was Comparable to the Ferrous Sulfate Control Diet in Rats

Objectives: To evaluate the iron bioavailability of biofortified and conventional cowpea beans (Vigna unguiculata L. Walph) in rats.

Methods: Biofortified (BRS Aracê, BRS Tumucumaque, and BRS Xiquexique) and conventional (BRS Pajeu) cowpea beans were supplied by EMBRAPA (Brazil) and had their chemical composition determined (AOAC, 2019). 40 male Wistar rats, 21 days of age, received in depletion phase (21 days), an Iron-free diet. In the repletion phase (14 days), animals were divided (n = 8) and received as iron source (12ppm): ferrous sulfate (FS); Pajeu (P); Xiquexique (X), Aracê (A); or Tumucumaque (T). The animals were fed 18-20g diet/day. At the end of both phases, blood samples from the rat tails were used to determine hemoglobin (Hb), Hb regeneration efficiency (HRE), and biological relative value of HRE (RBV). On the 36^th day, the animals’ liver was collected for iron levels (by atomic absorption spectrometry) and iron metabolism markers (by RT-PCR) determination. Data was analyzed by ANOVA and post-hoc Newman-Keuls (p < 0.05). Ethics Committee-UFES (013/2022).

Results: Pajeu was the only cowpea that presented tannins in its composition and had highest value of phenolic compounds then other beans. The iron content was similar between beans; however, the phytate/iron ratio was higher in Xiquexique (12.61), followed by Pajeu (12.00), Tumucumaque (11.04), and Arace (8.66). The iron intake was higher in FS, followed by the X, and A groups. Hb gain was similar between the biofortified beans and the FS control. The T group had the highest HRE% and RBV, similar to X. Furthermore, A group had highest gene expression of ferritin in the liver, similar to FS. Conversely, gene expression of transferrin in the liver was higher in the T than FS group. There was no difference in food intake and hepatic iron between groups (p >0.05).

Conclusions: The high values of phenolic compounds in Pajeu might have contributed to its lowest Hb gain. Likewise, the low Phytate/Fe Ratio favored absorption and storage of iron (as ferritin) by A group. T group induced a greater expression of transferrin, favoring a greater HRE% and RBV. The bioavailability of iron in biofortified beans was higher compared to the conventional, possibly due to their lower phenolic composition. Iron bioavailability must be considered in biofortification program targets to combat iron deficiency anemia.

Funding Sources: FAPES, CAPES