Kratz Mario, Marcovina Santica, Nelson James E, Yeh Matthew M, Kowdley Kris V, Callahan Holly S, Song Xiaoling, Di Chongzhi, Utzschneider Kristina M
From the Fred Hutchinson Cancer Research Center, Division of Public Health Sciences, Cancer Prevention Program (MK and XS) and Biostatistics Program (CD), Seattle, WA; the Division of Metabolism, Endocrinology & Nutrition, Department of Medicine, University of Washington, Seattle, WA (MK and KMU); the Departments of Epidemiology (MK) and Pathology (MMY), University of Washington, Seattle, WA; the University of Washington Northwest Lipid Research Laboratories, Seattle, WA (SM); Benaroya Research Institute, Virginia Mason Medical Center, Seattle, WA (JEN and KVK); the University of Washington Institute of Translational Health Sciences, Seattle, WA (HSC); and the VA Puget Sound Health Care System, Department of Medicine, Division of Endocrinology, Seattle, WA (KMU).
Am J Clin Nutr. 2014 Jun;99(6):1385-96. doi: 10.3945/ajcn.113.075457. Epub 2014 Apr 16.
Plasma phospholipid concentrations of trans-palmitoleic acid (trans-16:1n-7), a biomarker of dairy fat intake, are inversely associated with incident type 2 diabetes in 2 US cohorts.
The objective was to investigate whether the intake of trans-16:1n-7 in particular, or dairy fat in general, is associated with glucose tolerance and key factors determining glucose tolerance.
A cross-sectional investigation was undertaken in 17 men and women with nonalcoholic fatty liver disease and 15 body mass index (BMI)- and age-matched controls. The concentrations of trans-16:1n-7 and 2 other biomarkers of dairy fat intake, 15:0 and 17:0, were measured in plasma phospholipids and free fatty acids (FFAs). Liver fat was estimated by computed tomography-derived liver-spleen ratio. Intravenous-glucose-tolerance tests and oral-glucose-tolerance test (OGTT) and hyperinsulinemic-euglycemic clamps were performed to assess β-cell function and hepatic and systemic insulin sensitivity.
In multivariate analyses adjusted for age, sex, and BMI, phospholipid 17:0, phospholipid trans-16:1n-7, FFA 15:0, and FFA 17:0 were inversely associated with fasting plasma glucose, the area under the curve for glucose during an OGTT, and liver fat. Phospholipid trans-16:1n-7 was also positively associated with hepatic and systemic insulin sensitivity. None of the biomarkers were associated with β-cell function. The associations between dairy fat intake and glucose tolerance were attenuated by adjusting for insulin sensitivity or liver fat, but strengthened by adjusting for β-cell function.
Although we cannot rule out reverse causation, these data support the hypothesis that dairy fat improves glucose tolerance, possibly through a mechanism involving improved hepatic and systemic insulin sensitivity and reduced liver fat.
反式棕榈油酸（反式-16:1n-7）是乳制品脂肪摄入量的生物标志物，在美国的两个队列中，其血浆磷脂浓度与2型糖尿病的发病呈负相关。
目的是研究特别是反式-16:1n-7的摄入量，或一般的乳制品脂肪摄入量，是否与葡萄糖耐量以及决定葡萄糖耐量的关键因素相关。
对17名患有非酒精性脂肪性肝病的男性和女性以及15名体重指数（BMI）和年龄匹配的对照者进行了横断面调查。测量了血浆磷脂和游离脂肪酸（FFA）中反式-16:1n-7以及另外两种乳制品脂肪摄入生物标志物15:0和17:0的浓度。通过计算机断层扫描得出的肝脾比值估算肝脏脂肪。进行静脉葡萄糖耐量试验、口服葡萄糖耐量试验（OGTT）和高胰岛素-正常血糖钳夹试验，以评估β细胞功能以及肝脏和全身胰岛素敏感性。
在根据年龄、性别和BMI进行调整的多变量分析中，磷脂17:0、磷脂反式-16:1n-7、FFA 15:0和FFA 17:0与空腹血糖、OGTT期间葡萄糖曲线下面积以及肝脏脂肪呈负相关。磷脂反式-16:1n-7也与肝脏和全身胰岛素敏感性呈正相关。没有一种生物标志物与β细胞功能相关。通过调整胰岛素敏感性或肝脏脂肪，乳制品脂肪摄入与葡萄糖耐量之间的关联减弱，但通过调整β细胞功能则增强。
尽管我们不能排除反向因果关系，但这些数据支持这样的假设，即乳制品脂肪可能通过改善肝脏和全身胰岛素敏感性以及减少肝脏脂肪的机制来改善葡萄糖耐量。
