title: Influence of phytase, EDTA, and polyphenols on zinc absorption in adults from porridges fortified with zinc sulfate or zinc oxide.
abstract: Fortification of cereal staples with zinc is recommended to combat zinc deficiency. To optimize zinc absorption, strategies are needed to overcome the inhibitory effect of phytic acid (PA) and perhaps polyphenols. Five zinc absorption studies were conducted in young adults consuming maize or sorghum porridges fortified with 2 mg zinc as zinc sulfate (ZnSO4) or zinc oxide (ZnO) and containing combinations of PA or polyphenols as potential inhibitors and EDTA and phytase as potential enhancers. Fractional absorption of zinc (FAZ) was measured by using the double isotopic tracer ratio method. Adding phytase to the maize porridge immediately before consumption or using phytase for dephytinization during meal preparation both increased FAZ by >80% (both P < 0.001). Adding Na2EDTA at an EDTA:zinc molar ratio of 1:1 increased FAZ from maize porridge fortified with ZnSO4 by 30% (P = 0.01) but had no influence at higher EDTA ratios or on absorption from ZnO. FAZ was slightly higher from ZnSO4 than from ZnO (P = 0.02). Sorghum polyphenols had no effect on FAZ from dephytinized sorghum porridges but decreased FAZ by 20% from PA-rich sorghum porridges (P < 0.02). The combined inhibitory effect of polyphenols and PA was overcome by EDTA. In conclusion, ZnSO4 was better absorbed than ZnO, phytase used to degrade PA during digestion or during food preparation substantially increased zinc absorption from zinc-fortified cereals, EDTA at a 1:1 molar ratio modestly enhanced zinc absorption from ZnSO4-fortified cereals but not ZnO-fortified cereals, and sorghum polyphenols inhibited zinc absorption in the presence, but not absence, of PA. This trial was registered at clinicaltrials.gov as NCT01210794.
authors: Laboratory of Human Nutrition, Institute of Food, Nutrition, and Health, ETH Zurich, Zurich, Switzerland; and marica@sunrise.ch.
authors: Marica
authors: M
authors: Brnić
authors: Laboratory of Human Nutrition, Institute of Food, Nutrition, and Health, ETH Zurich, Zurich, Switzerland; and.
authors: Rita
authors: R
authors: Wegmüller
authors: Laboratory of Human Nutrition, Institute of Food, Nutrition, and Health, ETH Zurich, Zurich, Switzerland; and.
authors: Christophe
authors: C
authors: Zeder
authors: Clinical Trials Center, University and University Hospital Zurich, Zurich, Switzerland.
authors: Gabriela
authors: G
authors: Senti
authors: Laboratory of Human Nutrition, Institute of Food, Nutrition, and Health, ETH Zurich, Zurich, Switzerland; and.
authors: Richard F
authors: RF
authors: Hurrell
mesh_terms: D010832:6-Phytase / Q000494:pharmacology*; D000328:Adult; D001682:Biological Availability; D004492:Edetic Acid / Q000494:pharmacology*; D002523:Edible Grain / Q000737:chemistry*; D005260:Female; D005527:Food, Fortified; D006801:Humans; D007408:Intestinal Absorption; D007501:Iron / Q000378:metabolism; D058085:Iron Compounds / Q000378:metabolism; D019266:Iron, Dietary / Q000378:metabolism; D008297:Male; D010833:Phytic Acid / Q000494:pharmacology*; D059808:Polyphenols / Q000494:pharmacology*; D045868:Sorghum / Q000737:chemistry; D055815:Young Adult; D003313:Zea mays / Q000737:chemistry; D015032:Zinc / Q000378:metabolism*; D015034:Zinc Oxide / Q000378:metabolism; D019287:Zinc Sulfate / Q000378:metabolism
chemical_list: D058085:Iron Compounds; D019266:Iron, Dietary; D059808:Polyphenols; D019287:Zinc Sulfate; D010833:Phytic Acid; D004492:Edetic Acid; D007501:Iron; D010832:6-Phytase; D015032:Zinc; D015034:Zinc Oxide