Oxygen is essential for energy production in most cells and is carried by red blood cells that flow in blood vessels. The oxygen bound to hemoglobin in red blood cells is referred to as the ‘oxygen bound to hemoglobin.’ The oxygen dissolved in blood plasma is referred to as the ‘dissolved oxygen.’ Although the quantity of dissolved oxygen is less than that of oxygen bound to hemoglobin, it can flow to peripheral cells, especially those in the brain, heart, and eyes, even if capillaries are very narrow, since it is dissolved directly in blood plasma.
Perspectives on exposure to mild hyperbaric oxygen:
Exposure to mild hyperbaric oxygen is effective for elderly people, those with physical disability, as well as injured athletes, since no special movement needs to be performed under mild hyperbaric oxygen conditions. In future, exposure to mild hyperbaric oxygen may be investigated for: prevention and improvement of dementia, improvement of functional imbalances of autonomic (sympathetic and parasympathetic) nerves, e.g., menopausal disorders and emotional instability, maintenance and improvement of immunity, health, and physical fitness, and early recovery from an injury.
Exposure to mild hyperbaric oxygen at a low oxygen concentration (35–40% oxygen) does not result in enhanced levels of oxidative stress in rats [5, 19] and humans . Based on previous findings from experimental animal and human clinical studies, the effects of exposure to mild hyperbaric oxygen at 1266–1317 hPa with 35–40% oxygen are summarized in Table 1. It is noteworthy that these findings were obtained in the first step of exposure to mild hyperbaric oxygen.
Therefore, it is expected to define a suitable recommendation regarding a generally applicable protocol for exposure to mild hyperbaric oxygen in the subsequent step. This review describes the beneficial effects of exposure to mild hyperbaric oxygen on some metabolic diseases and related perspectives.