Hay Gry, Johnston Carole, Whitelaw Andrew, Trygg Kerstin, Refsum Helga
Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
Am J Clin Nutr. 2008 Jul;88(1):105-14. doi: 10.1093/ajcn/88.1.105.
Folate and cobalamin status changes markedly during infancy.
We aimed to examine the influence of breastfeeding on folate and cobalamin status in healthy infants.
In a longitudinal study, we measured serum folate, cobalamin, holotranscobalamin, holohaptocorrin, methylmalonic acid, and homocysteine at birth and at ages 6, 12, and 24 mo (n = 361, 262, 244, and 224, respectively). Breastfeeding status and nutrient intake were assessed by using questionnaires and 7-d weighed-food records (at 12 mo).
All indexes changed significantly from birth to age 24 mo (P < 0.001). Folate was high until age 6 mo and then declined. At age 6 mo, folate was positively correlated with duration of exclusive breastfeeding (rho = 0.29; P < 0.001). Cobalamin status declined after birth in breastfed but increased in nonbreastfed infants. Thus, holotranscobalamin (pmol/L) was lower in breastfed than in nonbreastfed children at age 6 mo [geometric mean: 37 (95% CI: 33, 40) and 74 (64, 86), respectively], at 12 mo [51 (46, 56) and 76 (70, 82), respectively], and at 24 mo [65 (50, 83) and 90 (85, 97), respectively; P < 0.05 for all]. Complementary feeding did not increase (6 mo) or modestly increased (12 mo) cobalamin status in breastfed children. At 12 mo, cobalamin intake (microg/d), excluding breast milk cobalamin, was lower in breastfed than in nonbreastfed infants [geometric mean: 1.4 (1.3, 1.6) and 2.4 (2.1, 2.6), respectively; P < 0.001]. However, after adjustment for total cobalamin intake, cobalamin status (ie, holotranscobalamin) remained significantly lower in breastfed than in nonbreastfed infants [54 (49, 59) and 70 (64, 78), respectively; P < 0.001].
Low cobalamin status is a characteristic finding in breastfed children. Reference limits according to age and breastfeeding status should be considered in early childhood.
婴儿期叶酸和钴胺素状态变化显著。
我们旨在研究母乳喂养对健康婴儿叶酸和钴胺素状态的影响。
在一项纵向研究中，我们在出生时以及6、12和24月龄时测量了血清叶酸、钴胺素、全转钴胺素、全运钴胺素蛋白、甲基丙二酸和同型半胱氨酸（分别为n = 361、262、244和224）。通过问卷调查和7天称重食物记录（在12月龄时）评估母乳喂养状况和营养摄入。
从出生到24月龄，所有指标均有显著变化（P < 0.001）。叶酸在6月龄前较高，之后下降。在6月龄时，叶酸与纯母乳喂养持续时间呈正相关（rho = 0.29；P < 0.001）。母乳喂养婴儿出生后钴胺素状态下降，而非母乳喂养婴儿则上升。因此，在6月龄时，母乳喂养儿童的全转钴胺素（pmol/L）低于非母乳喂养儿童[几何平均数：分别为37（95%CI：33，40）和74（64，86）]，12月龄时[分别为51（46，56）和76（70，82）]，以及24月龄时[分别为65（50，83）和90（85，97）；所有P < 0.05]。辅食添加并未增加（6月龄）或仅适度增加（12月龄）母乳喂养儿童的钴胺素状态。在12月龄时，母乳喂养婴儿除母乳钴胺素外的钴胺素摄入量（μg/d）低于非母乳喂养婴儿[几何平均数：分别为1.4（1.3，1.6）和2.4（2.1，2.6）；P < 0.001]。然而，在调整总钴胺素摄入量后，母乳喂养婴儿的钴胺素状态（即全转钴胺素）仍显著低于非母乳喂养婴儿[分别为54（49，59）和70（64，78）；P < 0.001]。
钴胺素状态低是母乳喂养儿童的一个特征性表现。在幼儿期应考虑根据年龄和母乳喂养状况制定参考限值。
