Green M H, Green J B, Akohoue S A, Kelley S K
Nutrition Department, The Pennsylvania State University, University Park, PA 16802, USA.
J Nutr. 2001 Apr;131(4):1279-82. doi: 10.1093/jn/131.4.1279.
To investigate the influence of vitamin A intake on the contribution of chylomicrons vs. holo retinol-binding protein to milk vitamin A, female rats were fed diets containing either 10 (n = 6) or 50 micromol vitamin A/kg body (n = 4) during pregnancy and through d 13 of lactation. [3H]Vitamin A was incorporated into each diet beginning on d 6 of lactation. Vitamin A concentrations on d 13 were significantly higher in dam liver (x 3), pup liver (x 2.6), milk (x 2.5) and mammary tissue (x 1.3) in rats consuming the higher level of vitamin A. In both groups, vitamin A specific activities in plasma and milk reached apparent plateaus by 2.33 d after addition of [3H]vitamin A to the diets. Vitamin A specific activity in milk was higher than in plasma at all times in both groups. The estimated minimum contribution of chylomicrons to milk vitamin A was 32 +/- 3% in rats fed the lower level of vitamin A vs. 52 +/- 10% at the higher level (P = 0.014). We concluded that dietary vitamin A, like triglycerides, may be directed to mammary tissue during lactation for preferential secretion into milk; thus, increasing vitamin A intakes will increase the contribution of dietary vitamin A to milk. In contrast to milk, mammary tissue vitamin A turns over very slowly.
为研究维生素A摄入量对乳糜微粒与全反式视黄醇结合蛋白对乳中维生素A贡献的影响，在妊娠期间及哺乳期第13天，给雌性大鼠喂食含10（n = 6）或50 μmol维生素A/kg体重（n = 4）的日粮。从哺乳期第6天开始，将[3H]维生素A掺入每种日粮中。摄入较高水平维生素A的大鼠，在第13天，母鼠肝脏（增加3倍）、幼鼠肝脏（增加2.6倍）、乳汁（增加2.5倍）和乳腺组织（增加1.3倍）中的维生素A浓度显著更高。在两组中，日粮中添加[3H]维生素A后2.33天，血浆和乳汁中的维生素A比活性均达到明显的平稳期。两组中，乳汁中的维生素A比活性在所有时间均高于血浆。摄入较低水平维生素A的大鼠，乳糜微粒对乳中维生素A的估计最小贡献为32±3%，而摄入较高水平维生素A的大鼠为52±10%（P = 0.014）。我们得出结论，日粮中的维生素A与甘油三酯一样，在哺乳期可能被导向乳腺组织，以便优先分泌到乳汁中；因此，增加维生素A摄入量会增加日粮中维生素A对乳汁的贡献。与乳汁相比，乳腺组织中的维生素A周转非常缓慢。
