Nutrient Absorption in Lean Versus Obese Individuals

我们最初的研究检查了两种标准饮食（2400千卡/天和3400千卡/天，每种饮食持续3天）下肥胖与瘦型个体的粪便和尿液能量损失。 最初的14个瘦的和9个肥胖的个体的初步结果没有显示出粪便或尿液能量损失的任何差异。两组粪便的热量范围很大，从2%到9%不等。与肥胖个体相比，瘦个体在高热量饮食中吸收更多（粪便能量损失较少）。 主要的肠道菌群类型，Firimutes和Bacteroidetes的百分比变化与营养负荷的变化有关。 厚壁菌门的百分比随着营养负荷的增加而增加，拟杆菌门的百分比随着营养负荷的增加而减少。此外，在偏瘦的个体中，主要粪便类型的这些变化与粪便能量损失相关，例如，Firmcutes/拟杆菌增加或减少20%与粪便能量损失的约150 kcal/天差异相关。 在此基础上，我们完成了一项新的研究，以证实和扩展上述发现。 在这项研究中，在过度和喂养不足期间测量了粪便能量损失和肠道微生物群的变化（基于计算的体重维持卡路里的150%和50%）。在此之后，志愿者随机接受抗生素口服万古霉素与安慰剂（以双盲随机方式）。 口服万古霉素在健康个体中不被吸收，并且会选择性地改变肠道细菌种群。 使用弹式量热法准确测量摄食量和粪便排出的热量，我们测量了在过度和不足的条件下以及口服万古霉素与安慰剂后的总热量和排出的%热量 我们证明了进食不足和口服万古霉素都增加了粪便热量损失，降低了血浆丁酸盐浓度，这是微生物代谢的标志。虽然喂养不足仅对微生物组的结构产生微小的变化，但口服万古霉素如预期的那样产生了广泛的影响。然而，在这两种情况下，一个物种，Akkermansia Muciniphila增加。Akkermansia Muciniphila是一种粘蛋白降解细菌，已在临床试验中证明可产生体重减轻。进食不足和口服万古霉素的热量损失程度约为80 kcal/天或摄入热量的2.5%。 这是第一项在人类中证明微生物组在营养收获中的直接作用的研究。

Our initial study examined stool and urine energy losses in obese versus lean individuals on two standard (2400 kcal/d and 3400 kcal/d each given over 3 days) diets. Preliminary results from an initial 14 lean and 9 obese individuals failed to show any difference in stool or urine energy loss. The range of calories stool was large, varying from 2 to 9 % in both groups. Lean individuals absorbed more (had less stool energy loss) on the higher calorie diet compared to obese individuals. Percent changes in the major gut phylotypes, Firimutes and Bacteroidetes, were associated with changes in nutrient load. Percent of Firmicutes increased with nutrient load while Bacteroidetes decreased. In addition, in lean individuals, these changes in the major phylotypes were associated with stool energy loss, such that a 20% increase or decrease in Firmcutes/Bacteroidetes was associated with approximately 150 kcal/day difference in stool energy loss. Based on this preliminary work, we completed a new study to confirm and extend the above findings. In this study, stool energy loss and changes in gut microbiota were measured during over and underfeeding (150 and 50% based on calculated weight maintaining calories). Following this, volunteers were randomized to receive the antibiotic oral vancomycin versus placebo (in a double blind randomized fashion). Oral vancomycin is not absorbed in healthy individuals and will selectively change the gut bacterial population. Using bomb calorimetry to measures exactly the amount of food ingested and stool calories excreted, we measured total and % calories excreted under conditions of over and underfeeding and after administration of oral vancomycin versus placebo We demonstrated that both underfeeding and oral vancomycin increased stool calorie loss and reduced plasma butyrate concentrations a marker of microbial metabolism. While underfeeding produced only small changes in the structure of the microbiome, oral vancomycin as expected produced widespread effects. However, in both cases, one species, Akkermansia Muciniphila increased. Akkermansia Muciniphila is a mucin degrading bacteria which has been demonstrated in clinical trials to produce weight loss. The extent of the calorie loss with both underfeeding and oral vancomycin was approximately 80 kcal/day or 2.5% of ingested calories. This is the first study to demonstrate in humans a direct role for the microbiome in nutrient harvest.