- Researchers are reporting that an environment with lower oxygen levels helped mice in a laboratory live longer.
- Experts say there’s evidence that lower oxygenated environments may also boost longevity in humans.
- They say low oxygen locales provide health benefits in much the same way as lower calorie diets.
A new study reports that laboratory mice living in a less oxygenated environment live longer than those that don’t.
Researchers from Massachusetts General Hospital in Boston and Harvard University said in a statement that, for the first time, scientists have shown “oxygen restriction” is associated with longer lifespan in mammals, highlighting its anti-aging potential.
The study was published today in open-access journal PLOS Biology.
The research team, led by Dr. Robert Rogers of Massachusetts General Hospital, used mice bred to age more quickly than other mice while still showing classic signs of mammalian aging throughout their bodies.
Researchers compared the lifespans of mice living at normal atmospheric oxygen levels (about 21%) to the lifespans of mice that at 4 weeks of age were moved to a living environment with an 11% proportion of oxygen – similar to that at an altitude of 5,000 meters, the equivalent of what would be experienced at a Mount Everest base camp.
The team reported the mice in the oxygen-restricted environment lived about 50% longer than the mice in normal oxygen levels, with a median lifespan of 23 weeks compared to 15 weeks.
The oxygen-restricted mice also had delayed onset of aging-associated neurological deficits.
Rogers told Medical News Today that previous studies on the effects of hypoxia (below normal oxygen levels) in other organisms such as fibroblasts and yeast motivated researchers to look at its effects on mammals.
There were also examples of mammals thriving in low-oxygen environments.
“It’s also known that the naked mole rat, a mammal whose long lifespan is an outlier given its size and phylogeny, spends the majority of its life in a relatively hypoxic burrow,” Rogers said.
The health benefits of lower oxygen levels
Rogers said oxygen restriction is analogous to caloric restriction, which he said is the longest studied and most effective intervention to increase lifespan in a variety of species.
In the current study, the researchers found that oxygen restriction didn’t cause the mice to eat more.
“One can go too far with caloric restriction and reach starvation, which is harmful, but a moderate reduction is beneficial,” Rogers explained. “Similarly, oxygen restriction is not anoxia (a condition in which blood isn’t able to carry enough oxygen) – but rather a decrease in oxygen concentration to a level that is beneficial in certain settings.”
Dr. Hesham Sadek is a cardiologist with UT Southwestern in Texas who researches the effects of hypoxia and was not involved in this study. He told Medical News Today the idea of less oxygen being better in some cases isn’t counterintuitive.
“There is mounting evidence that oxygen exerts a wide range of deleterious effects on lower organisms and on mammals and that it mediates normal as well as pathological aging,” Sadek said. “Low oxygen has been shown to enhance the endogenous heart regenerative capacity in mice and humans and has been shown by the same group that published the current report to prolong the life of mice carrying certain mitochondrial mutations.”
Could the study mean humans living in environments with less oxygen could be healthier than normal?
“The authors correctly reference some epidemiological studies that suggest that living in high altitude may have an impact on longevity, although these epidemiological studies are difficult to control and interpret,” Sadek said. “There is recent evidence from the German Aerospace Center in Cologne, Germany, that humans exposed to low oxygen after a heart attack can recover some heart function.”
Sadek said that though the mice were bred to live shorter-than-normal lives, “it is not far-fetched to extrapolate to normal aging, which I suspect would have a similar effect.”
“It is important to note that in this elegant study, as pointed out by the authors, the reason why the mice live longer is not clear,” Sadek noted. “An important effect of low oxygen would be on the extent of DNA damage, which was not directly tested in this paper – also correctly acknowledged by the authors. It would be important for future studies to determine in this model and others whether low oxygen does in fact prevent or reverse DNA damage.”
Sadek said he recently took part in research showing promise for improved heart function after a heart attack.
“Specifically, it shows that exposure to hypoxia could stop the progression or even reverse heart failure,” he said.
What levels of oxygen are the healthiest?
That doesn’t mean, however, that people should start depriving themselves of oxygen, said Kelly Johnson-Arbor, a medical toxicology physician at National Capital Poison Center who is also board-certified in hyperbaric medicine and was not involved in the study.
“Oxygen is a part of the air that we breathe every day; although a certain amount of oxygen exposure is required to sustain life, oxygen can also be harmful when excessive amounts are breathed in,” Johnson-Arbor told Medical News Today.
“High amounts of oxygen can cause unwanted exposures to oxygen free radicals, which are associated with cellular harm, DNA damage, aging, and other adverse health effects,” Johnson-Arbor said. “Because of this, exposure to high amounts of oxygen is not always beneficial. Low oxygen exposure can also result in harmful health effects due to decreased oxygen delivery to the brain, heart, and other organs.”
Rogers said the new study is just the beginning.
“It will take many studies to fully define the potential uses of oxygen restriction in wild type aging and to understand the molecular mechanisms through which it might be beneficial,” he said. “We view this initial report as laying the foundation for this important line of future research.”
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