羟自由基是机体内氧化性最强的活性氧，对生物分子可产生损伤作用，因此检测羟自由基产量对评估氧化损伤相关疾病，如缺血再灌注和代谢性疾病等有十分重要的意义。由于羟自由基在机体内存在时间非常短暂，因此许多生物学研究都采用其代谢终产物间接分析含量。但这类方法难以计算人体活性氧的产生速率。最近有研究发现，呼吸氢气或饮用含氢水可减少大脑、心脏、肝脏等器官损伤。许多证据发现，氢能够选择性中和羟自由基，尽管这种反应的分子基础目前仍不清楚。

Ohsawa等还证明，呼吸氢过程中，动脉和静脉氢气浓度存在差异，说明氢可以被组织利用（也许是经过皮肤扩散到周围），但目前尚无直接证据证明氢是否可被人体利用。日本学者曾经提出，经过饮用氢水，氢的消耗数量和机体自由基产量存在关系，提示氢可以在人体内发挥抗氧化作用。他们的研究发现，通过引氢水摄取的氢气有59%经过呼吸排除体外，有38%或以下可被人体利用。经过理论推算，人体每分钟每平方米体表面积可以利用1.0 μmol氢气。最近，该课题组为验证这一假说，采用呼吸低浓度氢气，检测氢被人体利用的规律。

研究对象为一名55岁男性志愿者，为减少大肠内源性氢气的干扰，实验前15小时避免任何药物、食物，先后进行7次检测，另外4次为午餐后检测。首先对志愿者呼出气（6分钟）的基础氢气浓度进行检测，通过一个单向阀吸入含有140–180 ppm低浓度氢气的空气，采集呼出气，潮气量检测连续(RS330, Minato Medical Science Co., Ltd., Osaka, Japan)，每2分钟用Douglas袋收集30秒呼出气，随后迅速用气密注射器将气样注射到生物气体分析仪(TRIlyzer 3000, Taiyo Ltd, Osaka, Japan)进行分析。经过公式计算最后发现，人体消耗氢气的速率为每分钟每平方米体表面积可以利用0.7 μmol氢气。

这一研究显然存在一定缺陷，首先只用一人作为研究显然不能代表人群的数据，只利用呼吸气体检测氢的浓度变化作为氢被消耗的计算也完全忽略了人体的复杂性，一方面有少数氢可能和生物分子结合不能扩散出人体，检测的敏感性也会影响计算结果。这种研究至少应该进行呼吸不同浓度氢进行回归性研究，因为理论上呼吸氢的浓度对氢的消耗不会造成影响，呼吸高浓度和低浓度获得类似的消耗量才能确定该研究方法的可行性，作者认为经过皮肤扩散可以忽略的看法也存在问题。

这一研究发表在一本书上，没有写成论文估计难以通过审稿人的裁决。

Molecular hydrogen consumption in the human body during the inhalation of hydrogen gas.pdf

Adv Exp Med Biol. 2013;789:315-21. doi: 10.1007/978-1-4614-7411-1_42.

Molecular hydrogen consumption in the human body during the inhalation of hydrogen gas.

Shimouchi A, Nose K, Mizukami T, Che DC, Shirai M.

Inhaling or ingesting hydrogen (H2) gas improves oxidative stress-induced damage in animal models and humans. We previously reported that H2 was consumed throughout the human body after the ingestion of H2-rich water and that the H2 consumption rate ([Formula: see text]) was 1.0 μmol/min/m(2) body surface area. To confirm this result, we evaluated [Formula: see text]during the inhalation of low levels of H2 gas. After measuring the baseline levels of exhaled H2 during room air breathing via a one-way valve and a mouthpiece, the subject breathed low levels (160 ppm) of H2 gas mixed with purified artificial air. The H2 levels of their inspired and expired breath were measured by gas chromatography using a semiconductor sensor. [Formula: see text] was calculated using a ventilation equation derived from the inspired and expired concentrations of O2/CO2/H2, and the expired minute ventilation volume, which was measured with a respiromonitor. As a result, [Formula: see text] was found to be approximately 0.7 μmol/min/m(2)BSA, which was compatible with the findings we obtained using H2-rich water. [Formula: see text] varied markedly when pretreatment fasting to reduce colonic fermentation was not employed, i.e., when the subject's baseline breath hydrogen level was 10 ppm or greater. Our H2 inhalation method might be useful for the noninvasive monitoring of hydroxyl radical production in the human body.