Dephytinisation with intrinsic wheat phytase and iron fortification significantly increase iron absorption from fonio (Digitaria exilis) meals in West African women

PLoS One. 2013 Oct 4;8(10):e70613. doi: 10.1371/journal.pone.0070613. eCollection 2013.

Abstract

Low iron and high phytic acid content make fonio based meals a poor source of bioavailable iron. Phytic acid degradation in fonio porridge using whole grain cereals as phytase source and effect on iron bioavailability when added to iron fortified fonio meals were investigated. Grains, nuts and seeds collected in Mali markets were screened for phytic acid and phytase activity. We performed an iron absorption study in Beninese women (n = 16), using non-dephytinised fonio porridge (FFP) and dephytinised fonio porridge (FWFP; 75% fonio-25% wheat), each fortified with (57)Fe or (58)Fe labeled FeSO4. Iron absorption was quantified by measuring the erythrocyte incorporation of stable iron isotopes. Phytic acid varied from 0.39 (bambara nut) to 4.26 g/100 g DM (pumpkin seed), with oilseeds values higher than grains and nuts. Phytase activity ranged from 0.17±1.61 (fonio) to 2.9±1.3 phytase unit (PU) per g (whole wheat). Phytic acid was almost completely degraded in FWFP after 60 min of incubation (pH≈5.0, 50°C). Phytate∶iron molar ratios decreased from 23.7∶1 in FFP to 2.7∶1 in FWFP. Iron fortification further reduced phytate∶iron molar ratio to 1.9∶1 in FFP and 0.3∶1 in FWFP, respectively. Geometric mean (95% CI) iron absorption significantly increased from 2.6% (0.8-7.8) in FFP to 8.3% (3.8-17.9) in FWFP (P<0.0001). Dephytinisation of fonio porridge with intrinsic wheat phytase increased fractional iron absorption 3.2 times, suggesting it could be a possible strategy to decrease PA in cereal-based porridges.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 6-Phytase / metabolism*
  • Adolescent
  • Adult
  • Africa, Western
  • Digitaria / chemistry*
  • Female
  • Food, Fortified
  • Humans
  • Informed Consent
  • Iron / metabolism*
  • Phytic Acid / chemistry
  • Triticum
  • Young Adult

Substances

  • Phytic Acid
  • Iron
  • 6-Phytase

Grant support

Financial support was provided by the Netherlands Fellowships Program NUFFIC. Part of fieldwork activities and equipment purchase was funded by the International Foundation for Science, (IFS Stockholm, Sweden), under the project reference IFS-E-4491. Another part of the field work such as the fonio treatement and porridge degradation test was funded by the European Union funded project FP6/EU/INCO FONIO project No. INCO CT-2005-015403 through a PhD scholarship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.