Department of Internal Medicine IV, University Hospital of Tübingen, Tübingen, Germany.
Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.
Am J Clin Nutr. 2019 Feb 1;109(2):288-296. doi: 10.1093/ajcn/nqy307.
Epidemiological studies suggest that an increased red meat intake is associated with a higher risk of type 2 diabetes, whereas an increased fiber intake is associated with a lower risk.
We conducted an intervention study to investigate the effects of these nutritional factors on glucose and lipid metabolism, body-fat distribution, and liver fat content in subjects at increased risk of type 2 diabetes.
This prospective, randomized, and controlled dietary intervention study was performed over 6 mo. All groups decreased their daily caloric intake by 400 kcal. The "control" group (N = 40) only had this requirement. The "no red meat" group (N = 48) in addition aimed to avoid the intake of red meat, and the "fiber" group (N = 44) increased intake of fibers to 40 g/d. Anthropometric parameters and frequently sampled oral glucose tolerance tests were performed before and after intervention. Body-fat mass and distribution, liver fat, and liver iron content were assessed by MRI and single voxel proton magnetic resonance spectroscopy.
Participants in all groups lost weight (mean 3.3 ± 0.5 kg, P < 0.0001). Glucose tolerance and insulin sensitivity improved (P < 0.001), and body and visceral fat mass decreased in all groups (P < 0.001). These changes did not differ between groups. Liver fat content decreased significantly (P < 0.001) with no differences between the groups. The decrease in liver fat correlated with the decrease in ferritin during intervention (r2 = 0.08, P = 0.0021). This association was confirmed in an independent lifestyle intervention study (Tuebingen Lifestyle Intervention Program, N = 229, P = 0.0084).
Our data indicate that caloric restriction leads to a marked improvement in glucose metabolism and body-fat composition, including liver-fat content. The marked reduction in liver fat might be mediated via changes in ferritin levels. In the context of caloric restriction, there seems to be no additional beneficial impact of reduced red meat intake and increased fiber intake on the improvement in cardiometabolic risk parameters. This trial was registered at clinicaltrials.gov as NCT03231839.
流行病学研究表明，摄入更多的红色肉类与 2 型糖尿病的风险增加有关，而摄入更多的纤维与风险降低有关。
我们进行了一项干预研究，以调查这些营养因素对 2 型糖尿病高危人群的葡萄糖和脂质代谢、体脂肪分布和肝脂肪含量的影响。
这是一项为期 6 个月的前瞻性、随机、对照饮食干预研究。所有组都将每日热量摄入减少 400 千卡。“对照组”（N=40）仅满足这一要求。“无红肉组”（N=48）除了减少红肉摄入外，还旨在增加纤维摄入至 40 克/天。干预前后进行人体测量参数和频繁采样的口服葡萄糖耐量试验。通过 MRI 和单质子磁共振波谱评估体脂肪量和分布、肝脂肪和肝铁含量。
所有组的参与者体重均减轻（平均 3.3±0.5 公斤，P<0.0001）。葡萄糖耐量和胰岛素敏感性改善（P<0.001），所有组的体脂和内脏脂肪质量均降低（P<0.001）。这些变化在组间没有差异。肝脂肪含量显著降低（P<0.001），各组之间没有差异。肝脂肪含量的减少与干预期间铁蛋白的减少呈正相关（r2=0.08，P=0.0021）。这一关联在一项独立的生活方式干预研究（图宾根生活方式干预计划，N=229，P=0.0084）中得到了证实。
我们的数据表明，热量限制导致葡萄糖代谢和体脂肪组成的显著改善，包括肝脂肪含量。肝脂肪的显著减少可能是通过铁蛋白水平的变化介导的。在热量限制的情况下，减少红色肉类摄入和增加纤维摄入对改善心血管代谢风险参数似乎没有额外的有益影响。该试验在 clinicaltrials.gov 注册，编号为 NCT03231839。
