Evaluation of Zinc Bioavailability in Humans from Foliar Zinc Biofortified Wheat and from Intrinsic vs. Extrinsic Zn Labels in Biofortified Wheat.
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Date
2015
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Abstract
Objectives: Zinc biofortification may be a sustainable way to improve Zn status, but questions
remain on Zn bioavailability. We produced a novel biofortified wheat by Zn foliar application, and a
separate wheat cultivar was intrinsically labeled with a Zn stable isotope. Goals were: a) To
compare fractional and total Zn absorption (FAZ-TAZ) from chapattis prepared with biofortified,
regular and postharvest fortified wheat; b) Compare the absorption of intrinsically and extrinsically
Zn labels from biofortified wheat.
Methods: Chapattis were prepared from flours with 100% and 80% extraction rates (ER). Meals
were administered to 2 women's groups (N=44) in randomized order. Bioavailability was measured
with double isotopic urinary technique with stable isotopes; four-day urines were collected and
isotopic enrichment measured.
Results: Foliar Zn application resulted in an increase of 45.6% of grain Zn. The control and
biofortified wheat contained 25±0.12 ppm and 46±1.37 ppm Zn and 0.830±0.04 g/100 g and 0.807
±0.03 g/100 g PA. The Zn:PA molar ratio for the unfortified, fortified and biofortified meals were 36,
63, 63 (100% ER) and 40, 67, 67 (80% ER). Mean total Zn in the intrinsically labeled wheat was 19.9±1.6 ppm. FAZ-TAZ data from the absorption studies are being analyzed.
Conclusions: Foliar application increased Zn concentration without significantly changing PA
concentration, and extraction rate is a determinant of the Zn:PA ratio. Assessment of FAZ-TAZ will
provide: a) Data on the potential of foliar zinc biofortified wheat, and b) proof that the double
isotope technique used to assess absorption of extrinsic Zn labels in biofortified wheat is valid.
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Signorell Coralie, Moretti Diego, Zeder Christophe, Tay Fabian, Boy Erick, Khetarpaul Neelam, Cakmak Ismail, Zimmermann Michael. Evaluation of Zinc Bioavailability in Humans from Foliar Zinc Biofortified Wheat and from Intrinsic vs. Extrinsic Zn Labels in Biofortified Wheat. European Journal of Nutrition & Food Safety. 2015 Special issue; 5(5): 863-864.