What is mitochondrial dysfunction and how does it affect aging
Mitochondria make the energy our cells need to function. However mitochondria are very delicate, and can be easily damaged, for example by oxidative stress or UV light, like sunlight. This damage causes the mitochondria to mutate and stop working, meaning the cell has no energy. And when cells have no energy, they die. Dead skin cells cause signs of premature aging such as uneven skin structure and a dull, tired surface. Researchers are looking for new ways to support mitochondrial function and repair damage. The science shows there are steps we can take to protect our mitochondria and keep our cells functioning at full power.
The powerhouse of the cell
You probably remember from school that mitochondria are the powerhouse of the cell, but do you remember what that means? What are mitochondria, and what do they do?
Mitochondria are tiny organelles found inside the cells of almost all living things. Their job is to produce adenosine triphosphate (ATP), a compound that cells use as fuel. This is called “cellular respiration.” Without ATP, your cells will die, and that makes mitochondria an important factor in how your body ages.
Each mitochondria has two membranes, or skins. The outer membrane is smooth, and gives the mitochondria a rounded or oval shape. Inside is a second membrane that is folded like an intestine. This increases the surface area of the membrane, making the mitochondria more efficient at turning food into ATP.
Between the membranes is a gel-like substance that contains mitochondrial DNA (mtDNA), RNA, and ribosomes. The mtDNA holds all the genetic information the mitochondria needs to function and replicate. RNA and ribosomes convert that information into actions, a bit like a computer reading data to run a program.
That means mitochondria is super important to cellular function, and mtDNA is the blueprint that makes it all work.
When mitochondria go wrong
Turning food into ATP is a complex chemical reaction, and it often goes wrong. When that happens, it leads to the production of Reactive Oxygen Species (ROS). These are free radicals that can lead to damage inside the mitochondria.
Free radicals are chemical compounds that contain a single electron. Because electrons always want to be in pairs, the molecule will “steal” an electron from other compounds to solve the imbalance. This destabilizes the other compounds, and can lead to damage and mutations. If free radicals get out of control, cells can even die. This is known as oxidative stress.
Mitochondria create free radicals as a byproduct of their chemical processes. That means they're at increased risk of oxidative stress. In fact, mitochondria produce the highest number of ROS found inside our cells.
To counteract this, mitochondria trap free radicals inside their outer membranes. That stops the free radicals from affecting cellular DNA, but it means they do a lot of damage inside the mitochondria, to the mtDNA. This leads to an increased amount of mutations in mitochondrial DNA, compared to other parts of the cell. We know that mtDNA mutates at a rate 10 times higher than that of nuclear DNA as a result.
While some mutations are good — that’s how evolution works — within mitochondria, they’re bad. As mtDNA undergoes more and more mutations, it begins to break down. The mitochondria becomes less effective at producing the ATP that powers the cell. It can even stop production completely. When that happens, our cells die.
What happens when cells die?
Cell death (“apoptosis”) is a normal part of the function of our bodies. Adult humans lose more than 50 billion cells each day. As part of the cellular turnover cycle, old cells are replaced by new ones and we never even notice. However when cells die prematurely, our bodies can’t replace them. That can lead to organ malfunctions, cancer, and degenerative diseases.
While all that sounds scary — and it is! — a good place to look for signs of mitochondrial health (or damage) is your skin. Your skin is your largest organ, and is exposed to the harshest conditions of any in your body. Its role is to protect all your internal organs from temperature extremes, UV damage, pollutants, bacteria and viruses. Skin is tough, and it goes through a lot every day, and that means it is constantly undergoing renewal.
Your skin is also thin and highly visible, so any changes in its structure can be seen almost immediately. If damage to your mitochondria causes cell functions to slow or stop, you’ll see it on your skin first. Just look for signs of premature aging like lines, wrinkles, and age spots.
How UV light affects mitochondria
Another factor that damages mitochondria is UV light. UV light mutates mtDNA, and our skin cells are exposed to it every time we go outside, through sunlight. This speeds up the rate of mtDNA mutations, and increases the chances of mitochondria slowing production of ATP.
That’s bad news for our cells because UV sunlight is everywhere, and it doesn’t take much to damage mtDNA. Just two weeks of sun exposure, like on a beach vacation, can increase mtDNA mutations by as much as 40 percent. The damage doesn’t go away once those cells have regenerated either. Although our skin cells can renew every few weeks, undoing the damage to mtDNA caused by UV light can take up to 16 months.
How to protect mitochondria and avoid signs of aging
The secret to healthy cells and youthful-looking skin lies at the smallest cellular level, with mitochondria. The more we can protect mtDNA from damage caused by ROS and UV light, the better our cells function.
Researchers are studying ways that we can support mitochondrial function. Clinical trials of a drug designed to treat Alzheimer’s, J147, show it can reverse the aging process in mice. The drug works by binding to a protein inside mitochondria called ATP synthase, which is responsible for generating the ATP that cells need to function. Scientists predict that ATP synthase could be targeted to treat a variety of age-related disorders.
J147 is derived from turmeric, a common spice used in Indian cooking. The active compound in turmeric, curcumin, has anti-inflammatory and antioxidant properties that can support your cells, protect mitochondria, and possibly delay the onset of neurodegenerative diseases. While you can’t get J147 directly from turmeric, increasing your intake of this spice could help protect you at a cellular level.
Another exciting discovery is the metabolite compound Urolithin A. This is a gut bacteria and it triggers mitophagy, the process of recycling old and damaged mitochondria. This in turn boosts mitochondrial turnover, preventing too many mutations of mtDNA. We can’t get Urolithin A from food, but our bodies make it when we consume ellagitannins, found in many fruits. Some of the highest sources of ellagitannins include raspberries (especially yellow raspberries), pomegranates and pomegranate juice, blackberries, and cloudberries.
We can also protect our mitochondria from oxidative stress using antioxidants. Antioxidants are molecules that carry a “spare” electron they give to free radicals to stop them stealing electrons elsewhere. This neutralizes ROS and prevents them from damaging mtDNA. Eating foods rich in antioxidants (such as fruit and vegetables, tea, and dark chocolate) and using skincare products containing antioxidants, can help protect your mitochondria from oxidative stress.
Finally, you can support your mitochondria by using UVA/UVB sunscreen. Sunscreen protects skin from signs of premature aging, and also from burns and even cancer. And while sunscreen can’t prevent damage caused by free radicals, it does prevent additional damage caused by UV light that speeds up the rate at which mtDNA mutates.
Most of us remember to pack on the SPF when we’re at the beach, but it’s just as important to use sunscreen on cloudy or cold days. UV light doesn't get blocked by clouds, so we can be exposed to it in all conditions. Many moisturizers and foundations now include SPF, so it’s easy to incorporate sunscreen into your daily skincare routine.
The signs of aging start in our bodies at a cellular level. Maintaining good health and aging well is a balancing act of diet, environment, and good skincare habits. Supporting mitochondrial functions through antioxidants and reducing UV exposure are important steps to keeping your cells healthy.