Zombie Cells Explained: What They Are and Why They Matter for Healthy Aging

Zombie cells sound like an affliction you might need to deal with during a zombie apocalypse. But this isn’t science fiction—zombie cells are staggering around your body right this second. Formally known as senescent cells, these guys are a normal part of human biology. But as with most things, healthy young bodies handle them much better than bodies than have logged half a century or so. Let’s get into the whats, whys, and hows of zombie cells, and why they matter for healthy aging.

What the heck are zombie cells?

We’ve established that you have them—but what are they? Basically, zombie cells are older or damaged cells (or both) that have refused to die the way healthy cells typically do. They’re no longer dividing, so they’re just kind of hanging out, all zombie-like, in a half-alive state that’s straight out of a horror movie. It’s known as senescence.

Creepiness factor aside, here’s the thing—zombie cells don’t function like normal cells because they aren’t replicating, but they’re still metabolically active. They secrete inflammatory chemicals and signaling molecules that can be disruptive to cells around them. And just like zombies in the movies, zombie cells can actually induce senescence in these neighboring cells.

Now, cellular senescence is actually a natural part of aging. In small amounts, these zombie cells actually keep damaged cells from becoming cancerous and support wound healing. But as we get older, more and more zombie cells accumulate throughout the body. Too many roaming packs of zombie cells can be problematic in more ways than one: interfering with normal cellular function, triggering chronic inflammation, and generally contributing to age-related decline.

So, how do you know you have them? Great question!

Common biomarkers of zombie cells

Doctors and scientists can’t just count zombie cells. They aren’t pale, decaying-looking things that shuffle or jerk around (clearly, you’re confusing zombie cells with actual zombies). Through a microscope, zombie cells can look a little weird—kind of like a runny, misshapen, freckled pancake instead of a smooth, round, compact dot. But the better approach to identify zombie cells in the body is to look for biomarkers. These chemical and/or genetic signs are like a big waving flag that indicate zombie cells are in the area.

It gets a little complicated, but basically, scientists look for higher-than-normal levels of certain proteins and enzymes. Sometimes immune cell pattern tracking is used as an indirect biomarker. All of these serve as a sign that you have more zombie cells hanging around than there should be.

What do zombie cells do in the body?

Wondering how zombie anything can possibly be good? When they function as intended, zombie cells actually serve an important purpose. It goes like this: something damages a cell (maybe it’s a DNA mutation, maybe it’s oxidative stress, maybe it’s reached its division limit), so it goes into cellular senescence as a safety precaution.

That means it stops dividing—and that’s a good thing. A damaged cell that keeps dividing can lead to cancer. In senescence, it essentially just shuts down its growth cycle. At the same time, it releases very specific chemical messages—basically an SOS to the immune system to come and clear it out, but it also helps coordinate tissue repair after injuries.

So what’s the problem? Have zombie cells earned a bad rap just because of their unfortunate name? Not quite. It’s really a numbers game. Zombie cells tend to accumulate with age, and the immune system just can’t keep up.

Given enough time, zombie cells can have cascading effects in the body’s tissues and organs. Remember those inflammatory secretions that infect neighboring cells? It’s called senescence-associated secretory phenotype or SASP, and it’s pretty nonstop—a steady stream of inflammatory chemicals and enzymes that can wreak havoc. Over time, the consequences are pretty dire:

• Tissue damage and slower repair. Healthy cells around zombie cells can be pushed into senescence or become less efficient at repairing themselves. Call it a zombie attack.
• Chronic inflammation. Inflammation becomes really persistent, stressing the immune system and contributing to age-related decline (yep, inflammaging).
• Increased disease risk. Research links the accumulation of zombie cells to conditions like osteoarthritis, atherosclerosis, Alzheimer’s disease, type 2 diabetes, and certain cancers.
• Visible signs of aging. Loss of skin elasticity, slower muscle recovery, and reduced energy may all be tied to cellular senescence.

Clearly, zombie cells are just lurking in the background—they’re actively contributing to the wear and tear we associate with aging.

A word on zombie cells, NAD and CD38

We’ve already mentioned zombie cells contribute to inflammation. Well, chronic inflammation activities CD38, an enzyme involved in immune function. CD38 is also an avid NAD consumer. If you’re a regular reader around here, you’re probably familiar with the fact that CD38 activity often begins to overexpress as we age. At the same time, NAD levels decline. And lower NAD, among other issues, means your cells have less cellular currency to do things like repair themselves, produce energy, and support healthy aging.

This vicious cycle (more zombie cells driving more inflammation causing more CD38 activity and less NAD) can accelerate the aging process even more. But the reverse is also true. By managing zombie cells, we may be able to help preserve NAD. Maintaining healthy NAD levels, meanwhile, may help the body better manage zombie cells.

So… should I be worried about zombie cells?

There’s no need to panic, but yes, it’s worth paying attention to zombie cells. That’s especially true if you’re at all interested in healthy aging and disease prevention (and aren’t we all?). Fortunately, research into zombie cells is positively booming, and we’re learning a lot about how to keep these guys in check to reduce their harmful effects. While there are experimental treatments in the works, you might be pleased to learn that lifestyle strategies are a great place to start.

What can I do about zombie cells?

Pop culture tells us the only way to kill a zombie is to go after its head. Zombie cells, on the other hand, aren’t so readily taken out. While researchers investigate senolytics, a kind of zombie cell-hunting compound that actively targets and clears senescent cells, here’s what you can do right now.

• Commit to regular exercise. Consider it one more reason you need to mindfully move your body every single day! Turns out, physical activity helps maintain a healthier balance of zombie cells and supports the immune system in its zombie cell-clearing activities.
• Eat foods high in nutrients. Focus on antioxidant-rich foods, like berries, leafy greens, and nuts, to help minimize oxidative stress that can actually push cells into senescence.
• Get enough sleep. A solid seven or eight hours helps keep your immune system strong and supports cellular repair.
• Manage stress levels. Elevated stress hormones—the kind that comes from unchecked anxiety about relationships, money, or the general state of the world—can accelerate cellular aging. Find healthy outlets, like a yoga practice, mindfulness techniques, breathing exercises, exercise, that sort of thing.
• Quit smoking and cut (way) back on drinking. If you need another reason to kick the habit, cigarettes and excessive amounts of alcohol are both tremendously harmful to DNA and your cells. In other words, they actively contribute to more zombie cells.

It’s not possible to eliminate zombie cells entirely, nor would you want to. But you can slow their accumulation and minimize their harmful effects. The idea is balance—keeping the helpful zombie cells in check to prevent a body-wide zombie apocalypse.

What do longevity experts say about zombie cells?

Longevity researchers are actively researching zombie cells, and some of the biggest names in the longevity space think they’re among the most promising areas for extending healthspan.

• David Sinclair often points to senescent cells as a key driver of aging. In his book Lifespan, he explains that zombie cells accelerate inflammation and tissue breakdown, and he’s optimistic about senolytic drugs as a future tool to clear them. Sinclair also emphasizes lifestyle factors—like exercise, healthy diet, and stress reduction—as practical ways to limit senescent cell buildup right now. He’s also a proponent of maintaining NAD levels through NAD precursors like NMN and NR, since higher NAD may support the body’s ability to repair damage and potentially manage senescent cell accumulation more effectively.
• Judith Campisi is a pioneer in senescence research at the Buck Institute for Research on Aging, and she’s been studying zombie cells for decades. Her work helped uncover the dual role of senescent cells—protective in small numbers, harmful in excess. She’s particularly interested in SASP and how it drives age-related diseases. Campisi believes therapies that selectively remove or reprogram zombie cells could be game-changing for aging-related health.
• James Kirkland. A leading researcher at the Mayo Clinic, Kirkland is one of the scientists most closely associated with senolytic research. His lab has published some of the most influential studies showing that clearing senescent cells in mice can improve physical function and delay age-related diseases. Kirkland sees senolytic therapies as a realistic intervention within our lifetime—once they’re proven safe and effective in humans.

All three have the same take. Zombie cells aren’t just a side effect of aging—they’re active players in the process. While the science is still evolving, their research is helping shape the next generation of anti-aging therapies.

The takeaway on zombie cells

They sound straight out of a horror flick, but zombie cells are a very real part of our biology. The science is moving fast, and we may soon have a way to take out excess zombie cells en masse. For now, take the advice of experts like Sinclair, Campisi, and Kirkland—move your body regularly, eat nutrient-dense foods, manage stress, sleep well, and avoid habits that actively damage your cells. At this point, that’s really the best defense against a zombie cell takeover in your body.