Nickel K P, Martin B R, Smith D L, Smith J B, Miller G D, Weaver C M
Department of Foods & Nutrition, Purdue University, West Lafayette, IN 47907, USA.
J Nutr. 1996 May;126(5):1406-11. doi: 10.1093/jn/126.5.1406.
Stable isotopes were used to compare calcium fractional absorption from intrinsically and extrinsically labeled bovine milk as well as intrinsically labeled dairy product and cheese analogue. Healthy Caucasian women were fed a controlled diet for 4 d during the follicular phase of their menstrual cycle. With breakfast on the third day, participants ingested milk containing 44Ca (intrinsic) and 42CaCl2 (extrinsic) or dairy products containing 44Ca. Total feces were collected for 2 d prior to and 10 d after isotope ingestion. Polyethylene glycol was administered to monitor completeness of fecal collections. Total calcium was determined by atomic absorption spectrophotometry, and isotopic abundance was determined by high resolution fast atom bombardment mass spectrometry. Fractional absorption was determined as the difference between the administered isotopic dose and the quantity of 44Ca or 42Ca excreted in feces. The fractional absorption of calcium from milk was not affected by the method of labeling, lactose content, fermentation or the chemical form of calcium in dairy products or cheese analogue.
使用稳定同位素比较来自内在和外在标记的牛乳以及内在标记的乳制品和奶酪类似物的钙分数吸收。健康的白种女性在月经周期的卵泡期接受4天的控制饮食。在第三天吃早餐时，参与者摄入含有44Ca（内在）和42CaCl2（外在）的牛奶或含有44Ca的乳制品。在摄入同位素之前2天和之后10天收集全部粪便。给予聚乙二醇以监测粪便收集的完整性。通过原子吸收分光光度法测定总钙，通过高分辨率快原子轰击质谱法测定同位素丰度。分数吸收被确定为给予的同位素剂量与粪便中排泄的44Ca或42Ca量之间的差异。牛奶中钙的分数吸收不受标记方法、乳糖含量、发酵或乳制品或奶酪类似物中钙的化学形式的影响。
