Studies indicate elevated blood ketone levels (e.g. from a Ketogenic Diet and/or Intermittent Fasting) may allow an individual to survive longer under conditions of reduced oxygen! Reference
Abstract
When exposed to hypoxia, intact mice, with elevated blood ketones, live longer than mice with normal blood ketones. To evaluate a possible mechanism responsible for this phenomenon a rat brain slice preparation was used to determine if brain tissue would utilize glucose or ketones preferentially during exposure to reduced oxygen. Reducing available oxygen in the incubation medium from 95%, in steps, to 5% produced the expected gradual reduction in the carbon dioxide formation from glucose. In contrast, reducing the oxygen level to 40 and 20% resulted in a statistically significant stimulation of the production of carbon dioxide from the ketone beta-hydroxybutyrate. At very low oxygen levels carbon dioxide production from either substrate was reduced. These results are consistent with the hypothesis that ketones can be used in addition to glucose as a substrate for brain energy production even during reduced oxygen availability. If the increase in carbon dioxide production from ketones can be equated with an increase in energy production from this supplemental substrate then ketones may be therapeutically useful in avoiding the collapse of brain function during moderate hypoxia.
The potential applications for this knowledge are vast. There are several sports which may benefit form this, most notably Free Diving.
The medical applications are even more promising. An individual could theoretically make themselves more resilient to critical situations in which their oxygen is limited such as heart attack, asphyxiation, drowning, trapped in an enclosed space, etc... by keeping themselves in a state of ketosis. This would generally be done through fasting and/or maintaining a ketogenic diet. In addition, it may be possible in the future to increase a patient's blood ketones through introducing them from outside. This could be through ingesting endogenous ketones, but it's not unreasonable to speculate that injection may be another way to introduce ketone bodies into the blood stream. In this scenario, ketone injections could potentially be used by EMT's and First Responders when encountering an individual at risk of oxygen deprivation.
Why Do Ketones Help?
Ketone bodies can be thought of as an alternate fuel source for the body derived from fats. Compare this to glucose, the more commonly utilized fuel which is derived from carbohydrates. Ketones can be utilized more efficiently by the body, and therefore uses less oxygen. Ketone utilization produces less toxic metabolic byproducts than glucose, making it a "cleaner" burning fuel for the body. This slower buildup of toxic byproducts when in ketosis may also be a factor in the survival time of the brain and other bodily tissues. Either way, as we continue to learn more and more about the properties of ketones their therapeutic utilization is likely to increase over time.