Biofortified beans of East Africa are not significantly higher in iron content relative to non-biofortified marketplace varieties

Authors: Glahn, Raymond; Wiesinger, Jason; LUNG'AHO, MERCY - International Institute Of Tropical Agriculture (IITA)

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2020
Publication Date: 7/20/2020
Citation: Glahn, R.P., Wiesinger, J.A., Lung'Aho, M. 2020. Biofortified beans of East Africa are not significantly higher in iron content relative to non-biofortified marketplace varieties. Journal of Nutrition. https://doi.org/10.1093/jn/nxaa193.
DOI: https://doi.org/10.1093/jn/nxaa193

Interpretive Summary: For the past 20 years, a nutritional strategy known as biofortification has been applied to enhance the amount of iron (Fe), an essential nutrient that humans can absorb from eating the common bean. This strategy simply involves identifying and or developing bean varieties with sufficiently higher Fe content that can yield nutritional benefit. This approach is based on several assumptions that must be met for this approach to be sustainable and effective. The present study examined these assumptions by collecting a multitude of bean samples from the market places and bean breeders of countries in eastern Africa, a region of the world targeted for biofortification due to high prevalence of iron deficiency anemia. Overall, the results indicate that the assumptions of the high Fe bean breeding approach are not met in the East African marketplace. Observations indicate that the so called "biofortified" lines generated by the high Fe breeding approach are providing no additional dietary Fe to the food system. This study is significant as it refutes claims that this major international initiative has been highly successful at providing additional dietary Fe in countries of East Africa.

Technical Abstract: For 20 years, the predominant approach for bean Fe biofortification is to breed for high Fe content. This approach is based on three assumptions: 1) the average Fe concentration in beans currently consumed in targeted regions is approximately 50 ug/g dry weight, 2) a 40 ug/g increase (target value 90 ug/g) can be sustained through traditional breeding, and 3) iron bioavailability from the biofortified bean will not decrease substantially to negate the increase in Fe concentration. This study examined these assumptions by collecting 76 marketplace samples (East Africa Marketplace Collection; EAMC) of multiple color classes from locations in Uganda, Rwanda, Democratic Republic of Congo, Burundi, Ethiopia, Kenya and Tanzania. Because market samples can be a mixture of seed varieties within a market class, 155 genotypes known to be representative of the market place were collected from bean breeders in the Pan-Africa Bean Research Alliance, and designated the East Africa Breeder Collection (EABC). The average EAMC bean Fe concentration was 72 ug/g, ranging from 52-93 ug/g, with a couple of outlying varieties at 105 ug/g (MAC9) and 129 ug/g (MAC49). The EABC collection averaged 68 ug/g (range of 51-90 µg/g). The 18 biofortified varieties within the EAMC averaged 73 µg/g (range of 55-94 ug/g), which is essentially equal to the overall mean (71 ug/g) and range (54-93 ug/g) of the non-biofortified bean varieties in the EAMC. Using a Caco-2 cell bioassay to measure Fe bioavailability, the results show that biofortified varieties of the EAMC do not deliver any additional Fe relative to non-biofortified varieties. These observations indicate that the assumptions of the high Fe bean breeding approach are not met in the East African marketplace. Furthermore, based on the Fe content and bioavailability data of this study, the biofortified bean varieties from these markets are providing no additional dietary Fe.