This statement appears in the January 2001 catalog of InteliHealth Healthy Home, the mail-order service of the highly respected InteliHealth Web site. It is not listed in Intelihealth's online catalog. Oxygen also acts as a cleaner, it cleans excreta and those toxins left in the body. The above claims are about as silly as anything I have seen. The body adapts to get what it needs by changing its breathing rate.
Blood returning to the lungs contains surplus oxygen.
Taking oxygen into the stomach through a liquid, pill, or food would not significantly raise the body's blood level of oxygen. The oxygen content of the earth's atmosphere has not changed significantly during the past 10,000 years. If enough oxygen is available to sustain life, the body will extract what it needs from the air and deliver what is needed to the cells. In mountainous regions where the air pressure is lowest, humans readily adapt to reasonable levels. It is possible for a device to add a tiny amount of oxygen to water in a sealed tank, but soon after the water is exposed to room air, most of it will quickly bubble out.