Efficacy of iron fortified cowpea flour in improving iron status of schoolchildren in malaria endemic rural Ghana

A.R. Abizari

Research output: Thesisinternal PhD, WU


Children in sub-Saharan Africa are more likely to have survived the critical first 1000 days of life carrying along unresolved micronutrient deficiencies into the school-age. Iron-deficiency is the most prevalent micronutrient problem affecting school-age children in sub-Saharan Africa and yet the most difficult to resolve. It is necessary to ensure an adequate iron intake through the diet of school-age children and school-based feeding intervention may be a way to improve iron intake of schoolchildren. Such a feeding intervention would be more sustainable if it relies on locally produced food(s) with the potential to support food sovereignty. In this context, this thesis investigated whether foods based on cowpeas, an indigenous legume crop originating from Africa, can be used in a school feeding setting to improve iron status of school-age children in Ghana.

The investigations in this thesis comprised cross-sectional dietary and iron status assessment of schoolchildren (n=383), cowpea acceptability among schoolchildren (n=120 mother-child pairs), chemical analysis of cowpea landraces (n=14), an in vivo iron bioavailability among young women (n=16) and a randomized cowpea intervention trial (n=241) conducted mainly in Tolon-Kumbungu district of Ghana.

The results indicated that iron-deficiency and iron-deficiency anaemia affect 8 and 7 out of every 10 schoolchildren respectively. It also showed that the probability of adequate dietary iron intake is 0.32 but much larger (~0.90) if schoolchildren benefitted from a school feeding programme. Mothers/caregivers intended to give cowpeas to their schoolchildren 2–3 times per week. The positive attitudes of mothers towards cowpea predicted their intention to give them to their schoolchildren but they were worried about the cost, long cooking time and the discomfort their children may suffer after consuming cowpeas. The chemical analysis showed that cowpeas contain appreciable amounts of iron (4.9–8.2 mg/ 100 gd.w) and zinc (2.7–4.1 mg/100 gd.w) but also high amounts of inhibitory phytate (477–1110 mg/100 gd.w) and polyphenol (327–1055 mg/100 gd.w). Polyphenol concentration in particular was higher (P<0.05) in coloured compared to white landraces. Iron bioavailability from red and white cowpeas were 1.4 and 1.7%, respectively, in NaFeEDTA-fortified meals and 0.89 and 1.2%, respectively, in FeSO4-fortified meals. Compared with FeSO4, fortification with NaFeEDTA increased the amount of iron absorbed from white and red cowpea meals by 0.05 and 0.08 mg (P < 0.05) respectively. Irrespective of the fortificant used, there was no significant difference in the amount of iron absorbed from the 2 varieties of cowpea. Finally the results from the intervention trial showed that fortification of whole cowpea flour with NaFeEDTA resulted in improvement of haemoglobin (P<0.05), serum ferritin (P<0.001) and body iron stores (P<0.001), and reduction in transferrin receptor concentration (P<0.001). Fortification also resulted in 30% and 47% reduction in the prevalence of iron-deficiency (ID) and iron-deficiency anaemia (IDA) (P<0.05), respectively.

Overall, this thesis has shown that in a malarious region with high iron-deficiency like (northern) Ghana, iron status of schoolchildren can be improved through the consumption of cowpeas within a school feeding programme. The improvement in iron status is however unlikely to result from the usual/conventional consumption of cowpeas but through fortification of whole cowpea flour with a highly bioavailable iron compound. This thesis has also shown that the most suitable iron compound for such whole cowpea flour fortification is NaFeEDTA irrespective of whether the cowpea has high or low concentration of polyphenols.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
  • Zimmermann, Michael, Promotor
  • Brouwer, Inge, Co-promotor
  • Armar-Klemesu, M., Co-promotor, External person
Award date24 May 2013
Place of PublicationS.l.
Print ISBNs9789461735263
Publication statusPublished - 2013


  • cowpea meal
  • fortification
  • iron
  • iron deficiency anaemia
  • nutritional state
  • school children
  • ghana
  • school meals
  • edta
  • bioavailability
  • nutrition programmes
  • malaria
  • food sovereignty


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