Why are cells damaged when you don't get enough oxygen?
Oxygen deprivation damages cells through a chain of mechanisms: energy deficit, overstimulation of nerve cells, and an assault by free radicals, partly triggered precisely when blood flow is restored. How severe the damage turns out to be depends on how long and how serious the deficit is.
ATP is the fuel for virtually everything a cell does. Without oxygen, the mitochondria, the cell's power plants, can no longer produce ATP through the normal route. This energy deficit is the starting point for most of the damage that follows.
Once the energy supply runs out, cells can no longer keep their ion pumps running. In brain cells, this leads to a build-up of glutamate, a signalling molecule that overstimulates nerve cells under these conditions. At the same time, too much calcium flows into the cell. Calcium in turn activates all kinds of breakdown processes, causing the damage to escalate rapidly.
Some of the damage only occurs when the oxygen supply is actually restored. The moment blood returns, the mitochondria produce an explosive amount of aggressive oxygen molecules, also known as free radicals. A particularly harmful molecule in this context is peroxynitrite, which attacks proteins, fats and DNA inside the cell. This is why cell damage after a heart attack or stroke does not stop as soon as blood flow resumes.
The damage is not limited to one type of cell death. Depending on how severe and how long the oxygen deprivation lasts, cells can succumb in several ways: uncontrolled cell death, programmed cell death, and newer forms in which iron or inflammatory signals play a role. Which form dominates differs from situation to situation.
In newborns with oxygen deprivation, the insulating layer around nerve fibres is particularly vulnerable. The cells that produce this layer are more sensitive than other brain cells, and damage to it can lead to lasting problems with movement and cognition. Of the newborns who survive such a severe oxygen shortage, one in four is left with permanent neuropsychological problems.
How severe the overall outcome is depends on three factors: how serious the deficit is, how long it lasts, and which organ or brain region is affected. That explains the wide variation in outcomes among people who go through a comparable event.
All claims are based on reviews, not primary randomised studies. The mechanisms (ATP depletion, excitotoxicity, free radicals, reperfusion injury) have been documented for decades and are widely supported in the literature. The more recent aspects, such as the role of a protein that regulates the shape of mitochondria and the contribution of newer forms of cell death, are less fully worked out. The findings on blood vessel walls under oxygen deprivation are so far limited to cell and animal models.
Can eating too little actually damage your cells?
Eating moderately less does not damage your cells - it actually protects them through a cellular clean-up mechanism. However, eating severely too little for a prolonged period can cause that same clean-up mechanism to overshoot and actually kill cells, so the line is drawn at extreme restriction.
How does air pollution damage your cells from the inside?
Air pollution damages your cells from the inside through oxidative stress: fine particulate matter causes an excess of harmful oxygen molecules that attack your DNA, energy factories, and immune system. Protection begins with limiting exposure, because the damage occurs at the cellular level.
Why do cells lose their ability to repair themselves over time?
Cells lose their repair capacity through a combination of declining energy stores, impaired DNA repair and the accumulation of 'burned-out' cells that secrete inflammatory substances. These are well-supported mechanisms, although it is still too early to act on them through supplements or therapies.
Does dehydration make your cells age faster?
There are biologically plausible indications that dehydration harms cells, but whether simply not drinking enough accelerates ageing in healthy people has not yet been demonstrated. Drinking enough remains sensible, though it cannot yet be marketed as an anti-ageing tip.
Does caloric restriction actually make your cells younger?
Caloric restriction slows ageing processes in cells, but whether your cells actually become younger as a result has not yet been proven in humans. The metabolic benefits, such as improved insulin sensitivity, have been demonstrated in human studies.
Why do some cells stop dividing as you age?
Cells stop dividing as a protection against damage and cancer, but the accumulation of such stopped cells contributes over the years to inflammation and age-related diseases. Drugs that target this are promising in animal research, but are not yet ready for use outside clinical studies.