Obesity and Diabetes Clinical Research Section, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Phoenix, AZ 85016, USA.
Am J Clin Nutr. 2011 Jul;94(1):58-65. doi: 10.3945/ajcn.110.010132. Epub 2011 May 4.
Studies in mice indicate that the gut microbiome influences both sides of the energy-balance equation by contributing to nutrient absorption and regulating host genes that affect adiposity. However, it remains uncertain as to what extent gut microbiota are an important regulator of nutrient absorption in humans.
With the use of a carefully monitored inpatient study cohort, we tested how gut bacterial community structure is affected by altering the nutrient load in lean and obese individuals and whether their microbiota are correlated with the efficiency of dietary energy harvest.
We investigated dynamic changes of gut microbiota during diets that varied in caloric content (2400 compared with 3400 kcal/d) by pyrosequencing bacterial 16S ribosomal RNA (rRNA) genes present in the feces of 12 lean and 9 obese individuals and by measuring ingested and stool calories with the use of bomb calorimetry.
The alteration of the nutrient load induced rapid changes in the gut microbiota. These changes were directly correlated with stool energy loss in lean individuals such that a 20% increase in Firmicutes and a corresponding decrease in Bacteroidetes were associated with an increased energy harvest of ≈150 kcal. A high degree of overfeeding in lean individuals was accompanied by a greater fractional decrease in stool energy loss.
These results show that the nutrient load is a key variable that can influence the gut (fecal) bacterial community structure over short time scales. Furthermore, the observed associations between gut microbes and nutrient absorption indicate a possible role of the human gut microbiota in the regulation of the nutrient harvest. This trial was registered at clinicaltrials.gov as NCT00414063.
研究表明，肠道微生物群通过促进营养吸收和调节宿主基因来影响能量平衡的两个方面，从而影响脂肪的形成，进而影响肠道微生物群。然而，肠道微生物群在多大程度上是人类营养吸收的重要调节因子仍不确定。
本研究使用经过精心监测的住院患者队列，测试改变瘦人和肥胖个体的营养负荷如何影响肠道细菌群落结构，以及他们的微生物群是否与饮食能量收获效率相关。
我们通过对 12 名瘦人和 9 名肥胖个体的粪便中存在的细菌 16S 核糖体 RNA(rRNA)基因进行焦磷酸测序，并通过使用爆炸式热量计测量摄入和粪便卡路里，研究了在卡路里含量不同的饮食（2400 与 3400 kcal/d）期间肠道微生物群的动态变化。
营养负荷的改变导致肠道微生物群的快速变化。这些变化与瘦人粪便能量损失直接相关，即厚壁菌门增加 20%，拟杆菌门减少相应的比例，与能量收获增加约 150 kcal 相关。瘦人过度喂养程度较高时，粪便能量损失的分数下降幅度更大。
这些结果表明，营养负荷是影响肠道（粪便）细菌群落结构的关键变量，可以在短时间内发生变化。此外，观察到的肠道微生物群与营养吸收之间的关联表明，人类肠道微生物群可能在调节营养吸收方面发挥作用。本试验在 clinicaltrials.gov 注册，编号为 NCT00414063。
