Rémond Didier, Machebeuf Marie, Yven Claude, Buffière Caroline, Mioche Laurence, Mosoni Laurent, Patureau Mirand Philippe
Institut National de la Recherche Agronomique, UMR 1019, Unité de Nutrition Humaine, Centre de Clermont-Ferrand-Theix, Saint Genès-Champanelle, France.
Am J Clin Nutr. 2007 May;85(5):1286-92. doi: 10.1093/ajcn/85.5.1286.
The rate of protein digestion affects protein utilization in elderly subjects. Although meat is a widely consumed protein source, little is known of its digestion rate and how it can be affected by the chewing capacity of elderly subjects.
We used a [1-(13)C]leucine balance with a single-meal protocol to assess the absorption rate of meat protein and to estimate the utilization of meat protein in elderly subjects with different chewing efficiency.
Twenty elderly volunteers aged 60-75 y were involved in the study. Ten of them had healthy natural dentition, and the other 10 were edentulous and wore complete dentures. Whole-body fluxes of leucine, before and after the meal (120 g beef meat), were measured with the use of a [1-(13)C]leucine intravenous infusion.
A rapid increase in plasma aminoacidemia and plasma leucine entry rate was observed after meat intake in dentate subjects. In complete denture wearers the increase in leucine entry rate was delayed (P<0.05), and the amount of leucine appearing in peripheral blood during the whole postprandial period was lower than in dentate subjects (P<0.01). Postprandial whole-body protein synthesis was lower in denture wearers than in dentate subjects (30% compared with 48% of leucine intake, respectively; P<0.05).
Meat proteins could be classified as fast digested proteins. However, this property depends on the chewing capacity of elderly subjects. This study showed that meat protein utilization for protein synthesis can be impaired by a decrease in the chewing efficiency of elderly subjects.
蛋白质消化率会影响老年受试者对蛋白质的利用。尽管肉类是一种广泛食用的蛋白质来源，但关于其消化率以及老年受试者咀嚼能力如何影响肉类消化率，人们所知甚少。
我们采用单餐方案的[1-(13)C]亮氨酸平衡法，评估肉类蛋白质的吸收率，并估计不同咀嚼效率的老年受试者对肉类蛋白质的利用率。
20名年龄在60 - 75岁的老年志愿者参与了这项研究。其中10人有健康的天然牙列，另外10人无牙且佩戴全口假牙。通过静脉输注[1-(13)C]亮氨酸，测量进食（120克牛肉）前后亮氨酸的全身通量。
有牙列的受试者摄入肉类后，血浆氨基酸血症和血浆亮氨酸进入率迅速增加。佩戴全口假牙的受试者亮氨酸进入率的增加延迟（P<0.05），并且在整个餐后期间外周血中出现的亮氨酸量低于有牙列的受试者（P<0.01）。佩戴假牙的受试者餐后全身蛋白质合成低于有牙列的受试者（分别为亮氨酸摄入量的30%和48%；P<0.05）。
肉类蛋白质可归类为快速消化的蛋白质。然而，这一特性取决于老年受试者的咀嚼能力。本研究表明，老年受试者咀嚼效率降低会损害肉类蛋白质用于蛋白质合成的利用率。
