Hackl Laura, Zimmermann Michael B, Zeder Christophe, Parker Megan, Johns Paul W, Hurrell Richard F, Moretti Diego
Laboratory for Human Nutrition, Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology Zürich, Zurich, Switzerland;
Laboratory for Human Nutrition, Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology Zürich, Zurich, Switzerland.
J Nutr. 2017 Mar;147(3):377-383. doi: 10.3945/jn.116.241778. Epub 2017 Feb 1.
Extruded rice grains are often cofortified with iron and zinc. However, it is uncertain if the addition of zinc to iron-fortified rice affects iron absorption and whether this is zinc-compound specific. We investigated whether zinc, added as zinc oxide (ZnO) or zinc sulfate (ZnSO), affects human iron absorption from extruded rice fortified with ferric pyrophosphate (FePP). In 19 iron-depleted Swiss women (plasma ferritin ≤16.5 μ/L) aged between 20 and 39 y with a normal body mass index (in kg/m; 18.7-24.8), we compared iron absorption from 4 meals containing fortified extruded rice with 4 mg Fe and 3 mg Zn. Three of the meals contained extruded rice labeled with FePP (FePP): ) 1 meal without added zinc (FePP-Zn), ) 1 cofortified with ZnO (FePP+ZnO), and ) 1 cofortified with ZnSO (FePP+ZnSO). The fourth meal contained extruded rice without iron or zinc, extrinsically labeled with ferrous sulfate (FeSO) added as a solution after cooking. All 4 meals contained citric acid. Iron bioavailability was measured by isotopic iron ratios in red blood cells. We also measured relative in vitro iron solubility from FePP-Zn, FePP+ZnO, and FePP+ZnSO expressed as a fraction of FeSO solubility. Geometric mean fractional iron absorption (95% CI) from FePP+ZnSO was 4.5% (3.4%, 5.8%) and differed from FePP+ZnO (2.7%; 1.8%, 4.1%) ( < 0.03); both did not differ from FePP-Zn: 4.0% (2.8%, 5.6%). Relative iron bioavailabilities compared with FeSO were 62%, 57%, and 38% from FePP+ZnSO, FePP-Zn, and FePP+ZnO, respectively. In vitro solubility from FePP+ZnSO differed from that of FePP-Zn (14.3%; < 0.02) but not from that of FePP+ZnO (10.2% compared with 13.1%; = 0.08). In iron-depleted women, iron absorption from FePP-fortified extruded rice cofortified with ZnSO was 1.6-fold (95% CI: 1.4-, 1.9-fold) that of rice cofortified with ZnO. These findings suggest that ZnSO may be the preferable zinc cofortificant for optimal iron bioavailability of iron-fortified extruded rice. This trial was registered at clinicaltrials.gov as NCT02255942.
挤压大米颗粒通常会同时强化铁和锌。然而，在铁强化大米中添加锌是否会影响铁的吸收，以及这是否具有锌化合物特异性尚不确定。我们研究了以氧化锌（ZnO）或硫酸锌（ZnSO）形式添加的锌是否会影响人体对用焦磷酸铁（FePP）强化的挤压大米中铁的吸收。在19名年龄在20至39岁之间、体重指数正常（以kg/m计；18.7 - 24.8）的缺铁瑞士女性（血浆铁蛋白≤16.5 μ/L）中，我们比较了4份含有4毫克铁和3毫克锌的强化挤压大米餐中铁的吸收情况。其中3份餐食含有标注了FePP的挤压大米（FePP）：1份未添加锌（FePP - Zn），1份与ZnO共同强化（FePP + ZnO），1份与ZnSO共同强化（FePP + ZnSO）。第四份餐食含有不含铁和锌的挤压大米，在烹饪后作为溶液添加硫酸亚铁（FeSO）进行外部标记。所有4份餐食都含有柠檬酸。通过红细胞中的同位素铁比率来测量铁的生物利用度。我们还测量了FePP - Zn、FePP + ZnO和FePP + ZnSO的相对体外铁溶解度，以FeSO溶解度的分数表示。FePP + ZnSO的几何平均铁吸收分数（95%CI）为4.5%（3.4%，5.8%），与FePP + ZnO（2.7%；1.8%，4.1%）不同（P < 0.03）；两者与FePP - Zn（4.0%；2.8%，5.6%）均无差异。与FeSO相比，FePP + ZnSO、FePP - Zn和FePP + ZnO的相对铁生物利用度分别为62%、57%和38%。FePP + ZnSO的体外溶解度与FePP - Zn不同（14.3%；P < 0.02），但与FePP + ZnO无差异（10.2%与13.1%相比；P = 0.08）。在缺铁女性中，用ZnSO共同强化的FePP强化挤压大米中铁的吸收是用ZnO共同强化大米的1.6倍（95%CI：1.4 - ，1.9倍）。这些发现表明，对于铁强化挤压大米的最佳铁生物利用度，ZnSO可能是更合适的锌强化剂。该试验在clinicaltrials.gov上注册为NCT02255942。
