Sarria Beatriz, Vaquero M Pilar
Departamento de Metabolismo y Nutrición, Instituto del Frío (CSIC), Madrid, Spain.
Nutrition. 2004 Sep;20(9):788-93. doi: 10.1016/j.nut.2004.05.002.
The Maillard reaction and lactose isomerization may be induced during the manufacture of infant formulas. We studied the effects of dehydration and sterilization on iron bioavailability from an infant formula in suckling and weanling rats.
In experiment 1, a previously reconstituted powdered infant formula and an in-bottle-sterilized liquid infant formula from the same manufacturer were fed from drinking bottles to 2-wk-old suckling rat pups for 7 d. In experiment 2, the same formulas were complemented with AIN-76 and fed to weanling rats for 7 d after a 4-d adaptation period. In both experiments, intake, body weight, and fecal and urinary excretions were monitored, and the following iron indexes were calculated: apparent absorption and retention and the coefficients percentage of absorption versus intake, percentage of retention versus absorption, and percentage of retention versus intake.
The liquid infant formula resulted in lower body weights on day 4, particularly among the younger rats that had significantly lower food intakes (P = 0.045). In weanling rats fed powdered and liquid infant formulas, food intake and body weight were not significantly different. The pups showed significantly higher absorption (percentage of absorption versus intake) and retention (percentages of retention versus absorption and retention versus intake) efficiencies than did the weanling rats (P < 0.001 for the three indexes). Hemoglobin values (P = 0.001) and liver iron concentrations (P = 0.009) were significantly higher in the weanling rats than in the pups. In contrast, erythrocyte iron concentrations and hematocrit were higher in the pups (P = 0.016 and 0.053, respectively).
In rat pups, iron bioavailability is negatively affected by the consumption of in-bottle-sterilized infant formula, possibly as the result of the content of Maillard reaction products, altered proteins, and lactulose. However, when this formula is included in a mixed diet and given to weanling rats, this detrimental effect no longer occurs.
婴儿配方奶粉生产过程中可能会引发美拉德反应和乳糖异构化。我们研究了脱水和灭菌对哺乳和断奶大鼠食用婴儿配方奶粉后铁生物利用度的影响。
在实验1中，将同一制造商预先调配好的粉状婴儿配方奶粉和瓶内灭菌的液态婴儿配方奶粉用奶瓶喂给2周龄的哺乳幼鼠，持续7天。在实验2中，同样的配方奶粉补充AIN-76，在4天适应期后喂给断奶大鼠7天。在两个实验中，监测摄入量、体重、粪便和尿液排泄情况，并计算以下铁指标：表观吸收和保留量以及吸收量与摄入量的百分比系数、保留量与吸收量的百分比系数、保留量与摄入量的百分比系数。
液态婴儿配方奶粉在第4天时导致体重降低，尤其是较年幼的大鼠，其食物摄入量显著较低（P = 0.045）。在喂食粉状和液态婴儿配方奶粉的断奶大鼠中，食物摄入量和体重没有显著差异。幼鼠的吸收效率（吸收量与摄入量的百分比）和保留效率（保留量与吸收量的百分比以及保留量与摄入量的百分比）显著高于断奶大鼠（三个指标的P均<0.001）。断奶大鼠的血红蛋白值（P = 0.001）和肝脏铁浓度（P = 0.009）显著高于幼鼠。相比之下，幼鼠的红细胞铁浓度和血细胞比容更高（分别为P = 0.016和0.053）。
在幼鼠中，瓶内灭菌的婴儿配方奶粉的食用会对铁生物利用度产生负面影响，这可能是美拉德反应产物、蛋白质改变和乳果糖含量的结果。然而，当这种配方奶粉包含在混合饮食中喂给断奶大鼠时，这种有害影响不再出现。
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