Studies on molecular hydrogen have evolved tremendously from its humble beginnings and have continued to change throughout the years. Hydrogen is extremely unique since it has the capability to act at the cellular level. Hydrogen is qualified to cross the blood brain barrier, to enter the mitochondria, and even has the ability to trans-locate to the nucleus under certain conditions. Once in these ideal locations of the cell, previous studies have shown that hydrogen exerts antioxidant, anti-apoptotic, anti-inflammatory, and cyto-protective properties that are beneficial to the cell. Hydrogen is most commonly applied as a gas, water, saline, and can be applied in a variety of other mediums. There are also no side effects involving hydrogen, thus making hydrogen a perfect medical gas candidate for the convention of novel therapeutic strategies against cardiovascular, cerebrovascular, cancer, metabolic, and respiratory diseases and disorders. Although hydrogen appears to be faultless at times, there still are several deficiencies or snares that need to be investigated by future studies. This review article seeks to delve and comprehensively analyze the research and experiments that alludes to molecular hydrogen being a novel therapeutic treatment that medicine desperately needs 1.
Hydrogen can be characterized as the lightest and most abundant chemical element. A large amount of hydrogen is usually found in water and organic compounds, which causes free hydrogen to be rare on Earth 5. According to the Hazardous Substances Data Bank, hydrogen is also an odorless, tasteless, colorless gas 6.
As a result of its unique features hydrogen has many advantageous characteristics. One major advantage that hydrogen contains is its ability to diffuse through membranes and enter the cytosol. Hydrogen can also enter the mitochondria and nucleus. This is extremely favorable since many known antioxidants lack the ability to target organelles and are not as effective in this manner. Molecular hydrogen is also believed to be advantageous in medical procedures since it is able to maneuver through the blood brain barrier. There also are few side effects involving hydrogen. It is proposed that few side effects occur, since it seems that hydrogen reacts with strong oxidants and its levels does not seem to interfere with cell signaling processes involving reactive oxygen species 2.
Out of the numerous observations evolved the applications of hydrogen. In 1888, the Annals of Surgery had recorded one of the very publications linking hydrogen and medicine. At that point in time unnecessary laparotomies were often performed since it was very difficult for surgeons to determine visceral injuries to the intestines and the stomach. It was also reported that a surgeon was able to use hydrogen gas to insufflate the gastro-intestinal canal to accurately determine and locate visceral injuries, avoiding unwarranted surgeries 3.
Today, hydrogen is still very instrumental and can be found in an assortment of fashions concerning medicine and scientific research. One medicinal approach that employs hydrogen is the breath hydrogen test. The breath hydrogen test is performed by measuring the amount of hydrogen that is produced by intestinal bacteria that are constantly synthesizing hydrogen as a result of fermentation of unabsorbed carbohydrates 7. The analysis of the results of the breath hydrogen test can serve as biomarkers and can be also used to compute oral-cecal transport, transit times, and overgrowth of bacteria. The breath hydrogen test is also used as biomarkers in clinical and scientific research ranging from biochemistry, dentistry, and physiology 5.
In 2007, Ohsawa et al., published “Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals” in Nature Medicine. Ohsawa et al., reported that hydrogen is able to react with cytotoxic oxygen radicals and protect against oxidative damage. These conclusions were made based upon experiments observing a rat model of focal ischemia and reperfusion. After ischemia was induced and reperfusion performed, it was observed that arterial blood contained elevated levels proportionate to the concentration of hydrogen that was inhaled. Also, it is suggested that the tissue was able to absorb hydrogen, since dissolved hydrogen was found at lower levels than the arterial blood. The study also suggests that hydrogen is able to prevent oxidative damage by reacting with the hydroxyl radical. This is important since the hydroxyl radical is believed to be the most dangerous oxygen species since there are no naturally occurring mechanisms to prevent its affects. As a result of the findings by Ohsawa et al., the convention of hydrogen has yet evolved. This publication has sparked many investigations concerning hydrogen as a selective reactive oxygen species scavenger and it its potential as an antioxidant therapy 2.