Mitochondrial Health and Ageing: The Cell's Power Plants, and What Actually Helps

If you've spent any time reading about longevity, you've met the mitochondria — usually called the "powerhouse of the cell," and usually followed closely by a supplement promising to recharge, repair, or rejuvenate them. The biology underneath the marketing is real and genuinely fascinating: mitochondria do decline with age, and that decline is part of why ageing feels the way it does. But the gap between the science and the sales pitch is wide. This is an honest look at what mitochondria actually do, what ageing does to them, and the short list of things that are genuinely worth your attention — written for people who'd rather know the truth than buy the hope.

What mitochondria actually do

Mitochondria are tiny structures inside almost every cell, and their job is energy. They take the fuel from your food and the oxygen you breathe and convert them into ATP — the molecule your cells spend to do everything they do, from contracting a muscle to firing a thought. A hard-working cell like a heart-muscle cell can contain thousands of them. When people talk about "cellular energy," this is what they mean: not a vague vitality, but the very concrete chemistry of mitochondria making ATP.

That central role is also why mitochondria matter so much for ageing. If the cell's power supply falters, everything downstream runs less well — which is exactly what seems to happen over a lifetime.

What ageing does to mitochondria

Here's the part that's solidly established. Mitochondrial dysfunction is one of the recognised "hallmarks of ageing" — the short list of fundamental processes that scientists agree drive biological ageing, set out in the landmark 2013 Hallmarks of Aging paper and kept in its 2023 update ¹². With age, mitochondria tend to become less efficient at producing energy and to accumulate damage, and that decline contributes to the gradual loss of function we associate with getting older ¹.

It's worth seeing this in context rather than isolation. Mitochondrial decline doesn't happen on its own — it's interwoven with the other hallmarks. There's a well-described two-way link between telomeres and mitochondria, for instance: telomere dysfunction can suppress the cell's mitochondrial "biogenesis" machinery (via a regulator called PGC-1α), and struggling mitochondria can in turn accelerate other ageing processes ⁵. If you've read our pieces on telomeres, cellular senescence, and the hallmarks of ageing, this is another thread in the same cloth. The mitochondria are also where the molecule NAD+ does much of its work, which is why they come up so often alongside NAD and energy metabolism.

Do "mitochondrial" supplements actually work?

This is where honesty matters most, because the decline is real and that makes the marketing persuasive. The short version: the supplement evidence is modest and mixed — promising in places, but nowhere near a fountain of youth.

Take the two most talked-about compounds. CoQ10 (coenzyme Q10) is a genuine, essential part of the mitochondrial energy chain, which makes it an obvious supplement candidate — but the US National Center for Complementary and Integrative Health states plainly that the evidence for CoQ10 in preventing heart disease is inconclusive, as is the research in heart failure ³. "Essential inside the cell" does not automatically mean "useful as a pill."

Urolithin A is the most interesting recent case, precisely because it shows how honest science looks. It's a compound your gut bacteria make from substances in foods like pomegranates, walnuts and berries, and it can trigger mitophagy — the cell's process of clearing out worn-out mitochondria. In a randomised, placebo-controlled trial in middle-aged adults, it improved muscle strength by roughly 12% and lowered a marker of inflammation — genuinely encouraging — but it missed its primary endpoint, showing no significant improvement in peak exercise power ⁴. That's the honest headline: early, mechanistically plausible, and worth watching, but not proven to do what the supplement ads imply. No supplement has been shown to "repair," "regenerate," or "reverse the ageing" of your mitochondria, and any product claiming to is ahead of the evidence.

What actually helps

The genuinely good news is that the most effective lever isn't sold in a bottle. Regular exercise is the best-supported way to improve mitochondrial function — physical activity stimulates the same biogenesis machinery (PGC-1α) that ageing tends to suppress, effectively prompting your cells to build more and better mitochondria ⁵. Endurance and resistance training both contribute, and the effect is one of the more reliable findings in the whole field.

Around that foundation sit the unglamorous basics that support cellular health generally: enough sleep, not smoking, and a sensible, mostly-whole-food diet. None of it is exciting, and that's rather the point — the things that genuinely help your mitochondria are the same things that help the rest of you, and they don't require a subscription.

What we see at the clinic

People interested in longevity often arrive with a shopping list of "mitochondrial" supplements and ask us which to take. Our honest answer usually surprises them: start with the parts that are free and proven — movement, sleep, not smoking — because those do more for your mitochondria than anything we could sell you. We're genuinely interested in the science here, including compounds like urolithin A, and we'll happily talk through what a study did and didn't show. But we won't dress up early or inconclusive evidence as a breakthrough, and we don't claim any drip or supplement "recharges" your cells. If a product's marketing sounds more certain than the research behind it, that gap is the most useful thing to notice.

Common questions

Should I take CoQ10 for energy or anti-ageing? The evidence doesn't support it as an anti-ageing or heart-disease-prevention measure — NCCIH calls the research inconclusive ³. There are specific medical situations where a doctor might suggest it, but as a general longevity supplement it isn't backed up.

Is urolithin A worth trying? It's the most promising of the bunch and appears safe, but its key trial missed its main goal ⁴, so it's fair to call it "interesting and unproven," not established. If you try it, do so with realistic expectations and ideally a conversation with your doctor.

Can a supplement actually repair my mitochondria? No supplement has been shown to repair, regenerate, or reverse the ageing of mitochondria. Mitochondrial dysfunction is a real hallmark of ageing ¹², but "real problem" and "this pill fixes it" are very different claims.

Does exercise really change my mitochondria? Yes — this is one of the better-established findings. Exercise stimulates the biogenesis pathways that build more and healthier mitochondria, the same machinery ageing tends to dampen ⁵.

How does this connect to NAD+ and telomeres? Closely. Mitochondria are a major site of NAD+ metabolism, and there's a documented two-way link between telomere health and mitochondrial function ⁵ — which is why these longevity topics keep overlapping. See our companion pieces on NAD and telomeres.

Key takeaway

Mitochondria really are central to how cells make energy, and their decline really is one of the hallmarks of ageing ¹² — so the interest is well-founded. What isn't well-founded is most of the supplement marketing: CoQ10's benefits are inconclusive ³, the most promising candidate (urolithin A) missed the main goal of its key trial ⁴, and nothing has been shown to "recharge" or rejuvenate your mitochondria. The honest, slightly boring truth is that the strongest thing you can do for them is move regularly, sleep well, and not smoke ⁵. Take the biology seriously, take the marketing with a large grain of salt, and put your energy into the foundations that actually work.