Water, the major body fluid in humans, has four main naturally occurring isotopologues, H216O, H217O, H218O, and H2H16O (i.e., HD16O) with different masses. The underlying mechanisms of the isotope-specific water-metabolism in the human gastrointestinal (GI) tract and respiratory system are largely unknown and remained illusive for several decades. Here, a new strategy has been demonstrated that provides direct quantitative experimental evidence of triple-isotopic signatures of water-metabolism in the human body in response to the individual's water intake habit. The distribution of water isotopes has been monitored in drinking water (DW; δD = -36.59 ± 10.64‰ (SD), δ18O = -5.41 ± 1.47‰ (SD), and δ17O = -2.92 ± 0.79‰ (SD)), GI fluid (GF; δD = -35.91 ± 7.30‰ (SD), δ18O = -3.98 ± 1.29‰ (SD), and δ17O = -2.37 ± 0.57‰ (SD)), and human exhaled breath (EB; δD = -119.63 ± 7.27‰ (SD), δ18O = -13.69 ± 1.23‰ (SD), and δ17O = -8.77 ± 0.98‰ (SD)) using a laser-based off-axis integrated cavity output spectroscopy (OA-ICOS) technique. This study explored a new analytical method to disentangle the competing effects of isotopic fractionations of water during respiration in humans. In addition, our findings revealed that deuterium-enriched exhaled semiheavy water, i.e., HD16O is a new marker of the noninvasive assessment of the ulcer-causing H. pylori gastric pathogen. We also clearly showed that the water-metabolism-derived triple-isotopic compositions due to impaired water absorption in the GI tract can be used as unique tracers to track the onset of various GI dysfunctions. These findings are thus bringing a new analytical methodology to better understand the isotope-selective water-metabolism that will have enormous applications for clinical testing purposes.

中文翻译：

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使用集成腔输出光谱法探索人呼气，胃液和饮用水中水的三同位素特征。

水是人类的主要体液，具有四种主要的自然同位素，分别为H216O，H217O，H218O和H2H16O（即HD16O），其质量不同。在人类胃肠道和呼吸系统中，特定于同位素的水代谢的潜在机制在很大程度上尚不清楚，并且几十年来仍然是虚幻的。在这里，已经证明了一种新的策略，该策略可以根据人体的饮水习惯，为人体中水代谢的三同位素特征提供直接的定量实验证据。已监测了饮用水中水同位素的分布（DW;δD= -36.59±10.64‰（SD），δ18O= -5.41±1.47‰（SD），δ17O= -2.92±0.79‰（SD）），GI流体（GF;δD= -35.91±7.30‰（SD），δ18O= -3.98±1.29‰（SD），δ17O= -2.37±0.57‰（SD）），以及使用基于激光的离轴集成技术的人呼气（EB;δD= -119.63±7.27‰（SD），δ18O= -13.69±1.23‰（SD）和δ17O= -8.77±0.98‰（SD））腔输出光谱（OA-ICOS）技术。这项研究探索了一种新的分析方法，以消除人类呼吸过程中水的同位素分馏的竞争作用。此外，我们的研究结果表明，富氘呼出的半重水，即HD16O是无创性评估引起溃疡的幽门螺杆菌胃病原体的新标志。我们还清楚地表明，由于胃肠道中水吸收受损而导致的源自水代谢的三同位素组合物可以用作跟踪各种胃肠道功能障碍发作的独特示踪剂。