What are mitochondria, and can you make them younger or more energetic?
Exercise is the only demonstrably effective way to improve mitochondria; for supplements such as NMN or urolithin A, the evidence in humans is still too thin to support a recommendation.
Mitochondria are small structures found in virtually every cell of your body. They convert nutrients into ATP, the immediate fuel form that cells use for almost everything they do. But they do more than supply energy: they maintain the chemical balance inside the cell, produce building blocks, and manage waste products.
As we age, things go wrong in mitochondria on several fronts at once. Damage accumulates in mitochondrial DNA. Energy production becomes less efficient. The generation of harmful oxygen radicals increases. And the system that clears away damaged mitochondria works less well. On top of that, levels of NAD+ in cells decline, a substance that energy metabolism cannot do without.
Exercise is the most well-established way to stimulate the formation of new mitochondria in muscles. Both interval training and regular endurance training produce a clear effect, and this finding holds up across multiple studies. The effect is substantial, though it does vary: the precise gain depends on training type, intensity and duration.
Supplements targeting mitochondria are on the rise, but the evidence lags behind the interest. NAD+ precursors such as NMN show mixed results in research. Substances that help clear away damaged mitochondria, such as urolithin A, or that protect mitochondria from damage, such as MitoQ, are promising in laboratory and animal research, but in humans long-term safety has not yet been established and reliable measures to assess the effect are lacking. Strong recommendations for supplements cannot be made at this time.
In hereditary mitochondrial diseases, where mitochondria fall severely short due to genetic defects, treatment options are unfortunately limited. No therapy yet meaningfully reverses the course of the disease. Symptom management and physical exercise are the main options. If you have questions about this because of illness in the family, discuss them with your doctor.
This answer is based on several reviews and one summary of randomised studies (on exercise and mitochondrial biogenesis). The exercise research is the best supported. The findings on supplements come from reviews of early clinical and preclinical research; the researchers themselves describe the results as mixed and the evidence base as insufficient for strong recommendations. The picture of how mitochondria function and decline with ageing is consistent and robust; how to reverse that with pills is where the evidence is thin.
What is mTOR and why does it matter in ageing?
mTOR is a switch in your cells that determines when they grow and when they clean themselves up. In ageing, that switch is set too high more often, and research shows that lowering that activity has a beneficial effect on long-term health.
What does insulin do to the ageing process?
Chronically too much insulin is probably bad for healthy ageing, but science does not yet know precisely what the ideal insulin balance is for you. Eating less processed food and moving more are the best-supported steps for keeping your insulin metabolism in good shape.
Does my metabolism really slow down as I get older?
Your metabolism does not slow down from your thirties onward, but after your sixties energy expenditure does decline noticeably. Muscle loss and reduced physical activity are the biggest culprits, and these are also the areas where you have the most influence yourself.
Does diabetes make a person age faster biologically?
Yes, diabetes measurably accelerates biological ageing: the risk of cardiovascular disease, dementia and early death increases, and keeping blood sugar well controlled is the most direct way to slow that process.
How can you speed up or improve your metabolism?
You can influence your metabolism, but the effects are more modest than popular claims suggest. Most of the gain lies in more everyday movement, more protein in your diet, and regular exercise, not in special supplements or meal-frequency tricks.
How does metformin work in your body?
Metformin lowers blood sugar primarily by causing the liver to produce less new glucose, without the risk of dangerously low blood sugar. Exactly how all the pieces of the mechanism fit together is not yet fully clear.