Molecular hydrogen (H2) is a gas that is found in trace amounts in the air (0.00005%). It can act as an antioxidant and is thought to protect cells from oxidative stress-related damage. Hydrogen can be inhaled as a gas at low concentrations (1-3%) or infused into water. A saturated solution of hydrogen contains 1.6 parts per million (ppm) hydrogen. In preclinical models, molecular hydrogen was most beneficial when used chronically as a preventative measure, before the onset of pathology. However, short-term clinical studies have failed to show clear cognitive benefits. Hydrogen therapy is generally considered safe.
A few small clinical trials have tested whether molecular hydrogen preserves cognitive function in populations at high risk for cognitive decline, in the form of hydrogen-rich water, hydrogen-rich saline infusions, or hydrogen gas inhalation. The inconsistent results may relate to the different sources and doses of hydrogen used in these studies.
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Daily consumption of 600 mL of hydrogen-rich water, containing 0.8-1.2 ppm hydrogen, for one month did not improve cognitive function in healthy young adults .
Randomized clinical trials including patients with mild cognitive impairment and early stage Parkinson's disease also failed to show significant benefits in preventing cognitive decline. Daily consumption of 300 mL of hydrogen-rich water (1.2 ppm hydrogen) for a year did not improve overall scores on cognitive tests in people with mild cognitive impairment . One small trial found that consumption of 1 L of hydrogen-rich water (1.6 ppm hydrogen) could slightly slow disease worsening in Parkinson's disease patients , but these findings were not replicated in a larger trial . It is unclear whether the results were different because the studies used different formulations of hydrogen-rich water.
In one study, stroke patients treated with 3% hydrogen gas therapy had less severe neurological impairment . The neuroprotection is thought to relate to a reduction in oxidative stress damage. Similar benefits were not seen with infusions of hydrogen-rich saline, as one small clinical trial reported only a marginally faster rate of recovery , while another study indicated there was no added benefit .
In the trial of people with mild cognitive impairment, APOE4 carriers were the only subgroup to show benefits on cognitive tests in response to hydrogen-rich water consumption , but there is no evidence for clinically apparent benefit.
Molecular hydrogen therapy has not been tested in patients with dementia. In preclinical models of Alzheimer's disease, hydrogen treatment reduced markers of oxidative stress and enhanced synaptic function, but did not reduce biological markers of Alzheimer's pathology (beta-amyloid and tau) .
Hydrogen-infused water has been granted Generally Recognized as Safe (GRAS) status by the FDA, which means that it is generally considered safe for consumption. In randomized clinical trials, molecular hydrogen intake was generally not associated with side effects, and animals consuming hydrogen-rich water throughout adulthood also did not show side effects . The consumed hydrogen only lasts in the body about one hour . Hydrogen gas is not flammable at concentrations lower than 4% , so hydrogen gas administered at 1-3% in a clinical setting is considered safe.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Hydrogen-infused water can be purchased in ready-to-drink aluminum pouches, or it can be produced at home by using hydrogen tablets, hydrogen sticks, a water ionizer, or a hydrogen infusion machine. Hydrogen-rich water is best consumed within an hour of opening, because the hydrogen gas is rapidly released back into the air . However, these products can vary widely in the level of hydrogen, and there is no clinically validated level for optimal benefit, or research-based evidence that any level of hydrogen can reduce the risk for dementia.
A scientific review on the potential of molecular hydrogen in preventing and treating diseases.