German Institute of Human Nutrition in Potsdam-Rehbruecke, DIfE, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.
Amino Acids. 2013 Feb;44(2):519-28. doi: 10.1007/s00726-012-1363-2. Epub 2012 Jul 31.
High-protein diets have been shown to alleviate detrimental effects of high-fat diets and this effect can be partially mimicked by dietary L-leucine supplementation. Here, we aimed to elucidate the early mechanisms and the specificity of leucine effects. We performed a 1-week trial with male C57BL/6 mice fed ad libitum with semisynthetic high-fat diets containing an adequate (10 % w/w, AP) or high (50 % w/w, HP) amount of whey protein, or supplemented with L-leucine corresponding to the leucine content within the HP diet (Leu) or supplemented with equimolar L-alanine (Ala). Food and water intake were monitored continuously using a computer-controlled monitor system and body composition changes were assessed using quantitative NMR. HP completely prevented the AP-induced accumulation of body fat. Leu and Ala resulted in a similar reduction of body fat accumulation which was intermediate between AP and HP. There were no significant effects on plasma glucose or insulin. Triacylglycerol content and gene expression of lipogenesis enzymes in liver as well as plasma cholesterol were reduced by HP compared to AP with Leu and Ala again showing intermediate effects. Body fat gain and liver triacylglycerols were strongly correlated with total energy intake. Water intake was rapidly increased by HP feeding and total water intake correlated strongly with total amino nitrogen intake. We concluded that the positive effects of high-protein diets on metabolic syndrome associated traits are acutely due to effects on satiety possibly linked to amino nitrogen intake and on the subsequent suppression of liver lipogenesis without evidence for a specific leucine effect.
高蛋白饮食已被证明可以减轻高脂肪饮食的有害影响，而这种效果可以通过饮食补充 L-亮氨酸部分模拟。在这里，我们旨在阐明亮氨酸作用的早期机制和特异性。我们对雄性 C57BL/6 小鼠进行了为期 1 周的试验，这些小鼠随意喂食半合成高脂肪饮食，其中含有足够的（10%w/w，AP）或高（50%w/w，HP）乳清蛋白，或补充与 HP 饮食中亮氨酸含量相对应的 L-亮氨酸（Leu）或补充等摩尔的 L-丙氨酸（Ala）。使用计算机控制的监测系统连续监测食物和水的摄入量，并使用定量 NMR 评估身体成分的变化。HP 完全阻止了 AP 引起的体脂积累。Leu 和 Ala 导致体脂积累的减少类似于 AP 和 HP 之间的减少。对血浆葡萄糖或胰岛素没有明显影响。与 AP 相比，HP 降低了肝脏甘油三酯含量和脂肪生成酶的基因表达，以及血浆胆固醇，而 Leu 和 Ala 再次显示出中间效果。与 AP 相比，HP 喂养时体脂肪增加和肝脏甘油三酯与总能量摄入强烈相关，而 Leu 和 Ala 则显示出中间效果。HP 喂养迅速增加了水的摄入，总水摄入量与总氨基酸氮摄入量强烈相关。我们得出结论，高蛋白饮食对代谢综合征相关特征的积极影响是急性的，可能是由于饱腹感的影响，这可能与氨基酸氮的摄入有关，随后抑制肝脏脂肪生成，而没有证据表明亮氨酸有特异性作用。
