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November 7, 2026

Findivoza

Science & Health

Cold extends lifespan through a hidden muscle signal, scientists find

Faizan Altaf

For more than a century, scientists have known something strange about the cold: animals kept at mildly cool temperatures tend to live longer. Worms, flies, fish and even mice all show the effect. What nobody could fully explain was how a chill turned into extra days, weeks or months of life. Now a team in Germany says it has found a key part of the answer, and it starts in an unexpected place: the muscles.

Researchers at the University of Cologne, led by molecular biologist David Vilchez, report in the journal Nature that mild cold switches on a chemical messaging system that runs from muscle to the rest of the body. The messenger is a small molecule called dihydrobiopterin, or BH2. In the tiny roundworm Caenorhabditis elegans, cold made muscle cells produce far more BH2, which then travelled to the gut and the nervous system, helping cells there stay healthy as the animal aged. When the researchers blocked the pathway, much of the lifespan benefit of the cold disappeared. When they switched the pathway on without any cold at all, the worms still lived longer.

The work was reported on 30 October 2026. It shows that the life-extending effect of cold is not simply a matter of everything slowing down. It is an active, organised process, with one tissue sending instructions to others. It also appeared to protect human cells in the laboratory against the toxic protein clumps seen in Huntington’s disease and amyotrophic lateral sclerosis (ALS), two conditions for which there are still no cures. That does not mean a treatment is around the corner. But it does give drug hunters a specific, testable target where before there was only a vague observation that cold seemed to help.

At a glance

What happened: Researchers at the University of Cologne found that mild cold triggers muscle cells in roundworms to produce a molecule called BH2, which travels to other tissues and extends lifespan.

Why it matters: It explains part of how cold slows ageing, shows the effect is actively controlled rather than a passive slowdown, and points to a possible route to treatments for diseases linked to harmful protein clumps, including Huntington’s disease and ALS.

What happens next: The team and other researchers will need to test whether the pathway works the same way in mammals, and whether it can be switched on safely, before any human treatment can be considered.

A century-old mystery

The link between cold and longevity is one of the oldest observations in ageing research. Scientists have known for more than a century that lowering the temperature extends lifespan in a wide range of animals, from the roundworm C. elegans to fruit flies and rodents. The effect is reliable enough that it has become a standard tool in the laboratory: keep the worms a few degrees cooler and they live measurably longer.

For a long time, the simplest explanation seemed good enough: chemical reactions slow down as temperatures fall, so perhaps the whole animal simply aged more slowly. But in recent years that explanation has started to look incomplete, and research has suggested that cold-induced longevity is an actively regulated process, with the body switching on specific pathways to protect itself. In earlier work in 2023, Vilchez and his team found that cold helped C. elegans clear away harmful protein clumps by activating proteasomes, the cell’s waste-disposal structures. The new study asks a bigger question: how does a signal that starts with temperature reach every part of the body?

The experiment: worms at three temperatures

The Cologne team, led by Vilchez and Hyun Ju Lee, worked with C. elegans, a transparent roundworm about a millimetre long that has been a workhorse of ageing research for decades. It was the first multicellular organism to have its entire genome sequenced. Its short lifespan, around two to three weeks in the laboratory, makes it possible to test ideas about ageing quickly.

The researchers compared worms kept at three temperatures: 15 degrees Celsius, which is moderately cold for the worm; 20 degrees, its comfortable standard temperature; and 25 degrees, which is warm. The worms kept at 15 degrees lived roughly 15 percent longer on average than those kept at 20 degrees, according to reporting of the study.

To find out what was driving the difference, the team mapped the worms’ metabolites, the small molecules produced by the body’s chemical processes, at each temperature. At the coldest temperature, 45 metabolites rose significantly. One stood out: BH2. Its levels rose sharply in the cold, and when the researchers genetically blocked its production, the extra longevity vanished.

How the signal travels: from muscle to gut and brain

The pathway the team mapped works like a relay. It begins in the muscles. Exposure to moderately cold temperatures increases production of an enzyme called CAT-4, largely in the worms’ muscles. CAT-4 is the rate-limiting enzyme for making BH2, which means it controls how fast BH2 can be produced. In humans, the equivalent enzyme is called GCH1.

Once made, BH2 does not stay in the muscle. It is stored and then released, travelling through the body to distant tissues, including the intestine and the nervous system. There, an enzyme called DHFR-1 converts BH2 into its bioactive form, tetrahydrobiopterin, or BH4. BH4 then acts as an essential helper, or cofactor, for another enzyme, PAH-1, which produces the amino acid tyrosine.

Tyrosine turned out to be a key player in its own right. When the researchers fed tyrosine to worms that could not make BH2, it helped them live longer, suggesting the amino acid carries much of the pathway’s benefit downstream. But the study is about the body’s internal production of tyrosine through this cold-triggered route, not about eating more of it.

The team also found that the pathway protects the cell’s protein balance, known as proteostasis. In worms engineered to model Huntington’s disease, the BH2 pathway suppressed the build-up of harmful protein clumps.

“We are excited to show that mildly cold temperatures trigger significant production of a specific metabolite, BH2, which is synthesized, stored, and subsequently released by muscle tissue,” Vilchez said. “BH2 then goes to other parts of the body, where it helps to maintain protein homeostasis and contributes to tissue health during aging.”

The most surprising result: no cold needed

Perhaps the most striking finding is that the cold itself may not be essential. When the researchers genetically boosted CAT-4 levels in the worms’ muscles, the animals lived longer even at normal or warmer temperatures. Switching on the first step of the pathway was enough to reproduce some of the benefits of the cold without lowering the temperature at all.

“We were genuinely surprised to find the supplementation significantly extended lifespan, even at standard and warmer temperatures,” Vilchez said. “Further experiments on human cells encourage us to look for treatments that mimic the beneficial effects of cold without requiring changes in body temperature.”

That result is what makes the study interesting beyond basic biology. If the pathway can be activated by a drug rather than by cold exposure, it could one day lead to treatments that copy the protective effects of a cold environment while the patient stays warm. “These findings suggest that specifically targeting a single tissue, such as muscle, could provide organism-wide protection,” Vilchez said. “This opens up new avenues for therapeutic approaches.”

What it could mean for Huntington’s disease and ALS

The researchers did not stop at worms. They also tested the pathway in human cells grown in the laboratory, including cells engineered to develop the protein problems seen in Huntington’s disease and ALS.

Huntington’s disease is an inherited condition in which a faulty protein gradually damages nerve cells in the brain, causing movement, thinking and mood problems that worsen over time. ALS, also known as motor neurone disease, destroys the nerve cells that control muscles, leading to progressive weakness. In both conditions, proteins that should fold neatly into their proper shapes instead misfold and clump together, and those clumps are toxic to cells.

In the human cell experiments, supplementing the cells with BH2 reduced the accumulation of abnormal proteins linked to Huntington’s disease. The same treatment reduced clumping of mutant versions of the proteins TDP-43 and FUS, which cause ALS when they misfold. BH2 and tyrosine supplementation also reduced signs of programmed cell death in human motor neurons carrying an ALS-associated mutation.

These are laboratory results in cells, not results in patients, and the gap between the two is large. But they are the reason the study has attracted attention beyond ageing research. Diseases in which proteins misfold and clump are among the hardest to treat, and a pathway that helps cells keep their proteins in order, in worms and in human cells alike, is a promising place to look.

The researchers did not test whether cold exposure, ice baths or cold showers extend human life, and their findings should not be read as advice to do any of those things. The worms lived at 15 degrees Celsius, a temperature that is mildly cold for a worm but has no direct equivalent for a person. The value of the work is in the mechanism it reveals, not in a lifestyle recommendation.

Why scientists are urging caution

For all the excitement, there are good reasons to treat the findings as a beginning rather than a breakthrough treatment. The most important is the distance between a worm and a person. C. elegans is a superb model organism, but it is a millimetre-long worm with about a thousand cells and no blood, brain or bones in the human sense. A pathway that extends its life by 15 percent may behave very differently in a mammal, and many discoveries that looked promising in worms have not survived the journey to human medicine.

ScienceAlert, reporting the study on 30 October, put the position plainly: so far the results have only been shown in experiments involving nematodes and human cells, and a great deal more research will be needed before anyone can think about how these effects could safely be transferred to living human patients. Singularity Hub, which also covered the study, made a similar point, noting that a biological response in cells does not automatically translate into a health benefit.

That caution extends to supplements. Nothing in this study shows that taking BH2 or tyrosine supplements will extend human life or protect against disease, and self-medicating on the basis of worm research would be a mistake. Any future treatment based on this pathway would need animal studies and carefully controlled human trials first, a process that takes years.

What happens next

The immediate next step is to test whether the pathway behaves the same way in mammals. Mice are the usual next model: they are warm-blooded, live for a couple of years, and cold exposure is already known to extend their lifespan. If boosting CAT-4, or its human version GCH1, in mouse muscle produces the same protective signal and lifespan effect, the case for pursuing a human treatment becomes much stronger.

For now, the study adds a clear, testable piece to a puzzle that has intrigued scientists for more than a century. Cold does not just slow life down. In worms at least, it switches on a conversation between tissues, with muscle doing the talking and the rest of the body listening. Whether that conversation can be started in people, and whether it can be started safely, is the question the next round of research will have to answer.

Frequently asked questions

What is BH2?

BH2, short for dihydrobiopterin, is a small molecule produced by the body’s metabolism. In the new study, it acts as a messenger: muscle cells make it in response to mild cold, and it travels to other tissues, where it is converted into BH4, a helper molecule enzymes need to do their jobs.

How much longer did the cold worms live?

Worms kept at 15 degrees Celsius lived roughly 15 percent longer on average than worms kept at 20 degrees Celsius, their comfortable standard temperature. A 15 percent gain in a worm that normally lives two to three weeks is a matter of days, but in ageing research it is a large effect.

Does this mean cold showers or ice baths will help me live longer?

No, not on the basis of this study. The research was done in roundworms and in human cells in a laboratory, not in people. It did not test cold exposure in humans, and the researchers have not recommended cold showers, ice baths or any other cold treatment.

What are Huntington’s disease and ALS?

Huntington’s disease is an inherited condition in which a faulty protein damages nerve cells in the brain, causing problems with movement, thinking and mood that get worse over time. ALS, or motor neurone disease, destroys the nerve cells that control muscles, causing progressive weakness. In both diseases, proteins misfold and form toxic clumps inside cells. The study found that BH2 reduced this clumping in laboratory models of both conditions.

Should I take BH2 or tyrosine supplements?

No. Nothing in this study shows that taking BH2 or tyrosine supplements will extend human life or protect against disease. The researchers warn that the BH2 pathway is delicate, and disturbing the balance of related molecules in the body could cause harm. Any treatment based on this research would need years of animal studies and human trials first.

Why do scientists study such a tiny worm to learn about human ageing?

Caenorhabditis elegans is about a millimetre long, lives for two to three weeks, and was the first multicellular organism to have its whole genome sequenced. Because it ages quickly and shares many basic biological processes with humans, researchers can test ideas about ageing in weeks rather than years. Findings in worms still need to be confirmed in mammals and then in people.

Conclusion

The idea that cold can slow ageing has been around for more than a century, but it was never clear how a drop in temperature turned into a longer life. The Cologne team’s answer is elegant: mild cold tells muscle cells to make more of a molecule called BH2, which travels through the body, becomes BH4, and helps cells make tyrosine and keep their proteins in order. In worms, that relay added roughly 15 percent to lifespan. In human cells, it reduced the toxic protein clumps linked to Huntington’s disease and ALS.

This article is for general information and education only. It is not legal or financial advice.

Sources

Faizan Altaf

Faizan Altaf is the founder and author of findivoza.com, a news blog covering world, Pakistan, business, technology, health and sport in plain English. He writes for general readers who want clear, trustworthy news without jargon. His work focuses on explaining what happened, why it matters, and what to watch next.

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