New evidence on the nutritional and functional benefits of biofortified crops

The effects of iron-biofortification on iron status and behavioral and physical performance

Jere D. Haas

Cornell University, Ithaca, Estados Unidos de América

Introduction and objectives. After plant breeders have successfully developed varieties of selected staple foods with increased iron content, the edible portion of the food crops must be tested for a number of qualities before the crops can be considered for introduction into the food supply. Efficacy, or the demonstration of a significant impact on the nutritional status of human subjects who consume the staple food under controlled experimental conditions, must be demonstrated. While efficacy studies of dietary iron interventions, such as consumption of biofortified foods, generally are limited to assessing blood biomarkers of iron status, the design of efficacy studies provide an opportunity to expand outcomes to include functional consequences of iron deficiency, such as physical performance and cognition. The objective of this presentation is to summarize the effects of consuming two iron-biofortified staple foods, pearl millet in India and beans in Rwanda, on iron status, physical performance and neurocognitive function. Development. Both efficacy studies employed a randomized, controlled, experimental study design. The iron-biofortified or similar control food was prepared to local tastes. Human research subjects consumed the foods for between 128 (Rwanda) and 180 (India) days, and meal consumption was monitored that allowed observation of dietary iron intakes from the total diet as well as precise quantification of the iron consumed from the biofortified staple food of interest. Both studies assessed iron status (blood hemoglobin, serum ferritin, soluble transferrin receptor, and total body iron) at baseline, midpoint and at the end of the feeding trial, and analysis focused on the feeding group difference in the change in iron status during the feeding period. In addition to iron status assessment, a subsample of subjects was given tests of physical performance and neurocognitive function. Identical methodologies were used in both studies. Consumption of iron-biofortified pearl millet was evaluated relative to control pearl millet in secondary school children, age 12-16 years, from western Maharashtra, India. A significant improvement in serum ferritin and total body iron was observed in iron-deficient adolescent boys and girls after consuming flat bread made from pearl millet twice daily for four months. This study demonstrated that iron-biofortified pearl millet is effective in improving ferritin and total body iron by four months. The prevalence of iron deficiency was reduced significantly in the high iron group, and for those children who were iron deficient at baseline, significantly more (64%) resolved their deficiency by six months. The improvements in hemoglobin and total body iron were significantly related to improvements in maximum oxygen consumption (VO2max), a measure of physical fitness, in girls. Iron deficient boys spent 18% less time in moderate to vigorous physical activity during school hours than non- deficient boys. Provision of the iron-biofortified pearl millet resulted in significant improvements in both behavioral (reductions in reaction time) and electrophysiological measures (EEG, increases in amplitudes) of attentional functioning on three tasks: simple reaction time (SRT), go/no-go (G/NG), and the attentional network (ANT). Improvements in the SRT were related to improvements in hemoglobin, while improvements in the GNG and ANT were related to improvements in serum ferritin. Consumption of iron-biofortified beans were tested relative to control beans for efficacy in Rwanda where iron-depleted university women showed a significant increase in hemoglobin and total body iron after consuming iron-biofortified beans for 18 weeks. While physical fitness (VO2max) declined over the 18 week feeding trial in both biofortified and control groups, the decline was attenuated in the iron-biofortified group. For the neurocognitive performance measures, provision of the biofortified beans resulted in significant improvements (reductions in RT) on two of the three behavioral measures of attentional function: GNG and a subset of the measures on ANT. Significant improvements on the EEG measures were observed on all three tasks of attentional function. Conclusions Iron-biofortification of select staple food crops, pearl millet in India and Beans in Rwanda, has been shown to be efficacious in improving iron status in adolescents and young women when feeding trials followed specified guidelines to ensure: a) adequate iron concentration difference exists between high-iron and control foods used in the study, b) subjects were iron deficient at baseline, c) sufficient consumption of the staple food was documented, d) adequate time elapsed to see a response, and e) appropriate biomarkers of iron status were used. Moreover, some functional correlates of iron deficiency were improved due to iron-biofortification, with the strongest effects seen in selected aspects of neurocognitive function.This research was supported by HarvestPlus.