What has been tried, in people and in animals, how far each idea has got, and who is working on it. We gather and explain; we don't judge.
Some effects of aging have been reversed in animals such as mice. In people, the approaches aimed at reversing aging are still being tested. How far each has got: cell reprogramming, stage 2 (small studies in people); plasma exchange and young blood, stage 3 (large studies in people); regrowing the thymus, stage 2 (small studies in people); clearing old cells, stage 2 (small studies in people); gene therapies, stage 2 (small studies in people). None has reached stage 4, widely recommended. Some drugs and supplements, and lifestyle programmes such as exercise and diet, have reached stage 4, but are studied for slowing aging, not reversing it.
Stages come from the research counted on each topic page below. How stages work
The World Health Organization's disease classification, the ICD, does not classify old age as a disease. Its “old age” category is used to code unclear statements by doctors on death certificates and medical records. In ICD-11 that category was renamed “Ageing associated decline in intrinsic capacity” to prevent misunderstandings. Some researchers are testing aging itself as a target: the main outcome of the TAME trial of metformin was shaped by advice from the US Food and Drug Administration (FDA) on aging-related uses.
Sources: World Health Organization: Frequently asked questions: “Old age” ↗ · Innovation in Aging: Trials of Geroscience-Based Therapeutics: the TAME example (2018) ↗
In mice, changing levels of certain molecules called transcription factors reversed some effects of aging. In old mouse livers, raising one of these molecules, EZH2, shifted gene activity toward a younger pattern and reduced fat buildup and scarring. That work carries a warning: these molecules affect many genes, so changing them can have unintended effects, and much more study is needed before use in people. In sea squirts, short electrical pulses extended life, with about 75% of treated animals alive and healthy a year later. Researchers say it is an open question whether the electrical approach can be applied to humans.
Sources: nih.gov: Manipulating gene activity to reverse aging ↗ · woods.stanford.edu: Electrical pulses reverse aging in sea squirts, offering clues for extending human longevity ↗
Biological age reflects the state of a person's body, not just the time since birth. One NIH article describes it as the damage that builds up across tissues and organs. People of the same calendar age can differ a lot in health, which is one reason the idea matters. A review notes there is no agreement on the best way to measure it, and different methods can give different results.
Sources: ncbi.nlm.nih.gov: New insights into methods to measure biological age: a literature review - PMC ↗ · nih.gov: Gauging biological age to predict future health ↗
Some small studies suggest biological age measures can go down, but the evidence is early. In a pilot trial of 43 healthy men aged 50-72, an 8-week diet and lifestyle program was linked to a 3.23-year lower DNA-based age than the control group. Within the treated group, the average drop was 1.96 years, which only showed a strong trend toward significance. In a separate analysis of clinical trial blood samples, three cycles of a fasting-mimicking diet were linked to a 2.5-year drop in median biological age. Harvard-led researchers found stress from surgery, pregnancy or severe COVID raised biological age signs, which were reversed after recovery. The authors note these clocks are biomarkers that may reflect biological age or could be driven by other factors not yet identified.
Sources: PubMed abstract: Potential reversal of epigenetic age using a diet and lifestyle intervention: a pilot randomized clinical trial. ↗ · PubMed abstract: Fasting-mimicking diet causes hepatic and blood markers changes indicating reduced biological age and disease risk. ↗ · news.harvard.edu: How dynamic is biological age? ↗
Public claims and headlines, quoted word for word from the article, next to how far research on what was tested has got. We don't judge the people or companies involved.
“Drug giants Eli Lilly and Novo Nordisk say patients taking their drugs age less quickly, according to readouts from molecular “aging clocks.”
Eli Lilly and Novo Nordisk · MIT Technology Review · Oct 6, 2026 · Read the article ↗
“Aging has a relatively simple explanation and is apparently reversible," wrote Sinclair.”
David Sinclair · MIT Technology Review · Jan 27, 2026 · Read the article ↗
“Our bodies hold a backup copy of our youth that can be triggered to regenerate, said Sinclair, the senior author of a new paper showcasing the work of his lab and international scientists.”
David Sinclair · CNN · Jan 12, 2023 · Read the article ↗
“Although the increase in lifespan was modest, the company says the research provides a demonstration of age reversal in an animal.”
Rejuvenate Bio · MIT Technology Review · Jan 9, 2023 · Read the article ↗
This review looks at past studies of red and near-infrared light on aging-linked conditions.
Original title: Red Light Therapy and Mitochondrial Rejuvenation in Age-Related Disorders.This study linked estrogen signals and hormone therapy to slower aging clock markers and lower death risk.
Original title: Hormone replacement therapy through the lens of epigenetic clock: estrogen signals, glycemic status, and lifespan.This is a planned small trial that is still recruiting, and no results have been posted yet.
Original title: Ultraformer MPT Combined With Fractional CO2 Versus Fractional CO2 Alone for Facial RejuvenationThis is a trial sign-up listing, and it is still recruiting people.
Original title: PLLA and CaHA-R for Aesthetic RejuvenationThis review looks at how cancer treatments can leave cells in a state of stress called senescence.
Original title: Reshaping the tumor immune microenvironment via therapy-induced senescence: senescence-associated secretory phenotype networks and senolytic strategies.This study is a trial that is still signing up people by invitation, and no results have been posted yet.
Original title: Systemic and Topical Geroprotective Rejuvenation Assessed by START/REST Aging Clocks“It gives us a lot of control,” says Rosenzweig-Lipson. “And the ability not just to turn it on, but to turn it off and not leave on expression longer than is necessary to rejuvenate the cells.”
“Since then, Life Biosciences has studied the approach in rodents and monkeys and has not seen serious adverse effects of the treatment, says Sharon Rosenzweig-Lipson, chief scientific officer at the company.”
“Reprogramming has a big upside if it can be used safely in people,” says Matt Kaeberlein, co-founder of Optispan, a longevity-focused preventative medicine company in Seattle, Washington. “The technology is still really early, and the potential for catastrophic side effects is high.”
“TAME is not a moonshot. It’s not even about scientific achievement really, it’s more about political achievement. Metformin is a tool to get aging as an indication.”
“But it’s premature to make any clinical recommendations based on the results from our study. NMN needs to be tested in more people and for longer periods of time to determine if it has anti-ageing effects in humans,”
“Finding an effect in muscle tissue is very interesting and does demonstrate that NMN is not inert,”
Companies in this area, in their own words, with their registered human trials. Listing a company is not an endorsement or investment advice.
“Alkahest, a Grifols subsidiary, is a research and drug discovery company mining the deepest layers of plasma knowledge to inform the development of potential transformative therapies and solutions for patients.” (from its website)
Registered human trials as lead sponsor: 12 (Phase 2, No phase). ClinicalTrials.gov ↗
We couldn't read a description from its website.
Registered human trials as lead sponsor: 9 (Phase 2, Phase 1, No phase). ClinicalTrials.gov ↗
“Our mission is said simply, yet it is quite ambitious. Calico is working to better understand the biology of aging and using those insights to advance foundational discoveries into potential medicines that enable people to lead longer and healthier lives.” (from its website)
Registered human trials as lead sponsor: 8 (Phase 1, Phase 2, No phase, Phase 1 and Phase 2). ClinicalTrials.gov ↗
We couldn't read a description from its website.
Registered human trials as lead sponsor: 7 (Phase 2, Phase 1). ClinicalTrials.gov ↗
“Pioneering thymus regeneration and longevity research. Join us in the fight against age-related immune decline.” (from its website)
Registered human trials as lead sponsor: 1 (Phase 2). ClinicalTrials.gov ↗
“Life Biosciences is a biotechnology company pioneering cellular rejuvenation using epigenetic restoration to reverse diseases of aging.” (from its website)
Registered human trials as lead sponsor: 1 (Phase 1). ClinicalTrials.gov ↗
Oct 8, 2026 · Life Biosciences (company press release)“The data demonstrated that a single intravitreal administration along with daily oral doxycycline was well-tolerated through Day 56 in all three participants and showed preliminary signals of improvement in visual field testing in two participants.” Source ↗
“Early experiments have shown that the ability of cells to resist stressors that give rise to disease can be restored. At Altos, we are focused on understanding how we can translate this science to help people live healthier lives.” (from its website)
No human trials registered on ClinicalTrials.gov as lead sponsor.
“Cambrian Bio is developing drugs targeting the underlying drivers of the metabolic decline and dysfunction experienced by every person.” (from its website)
No human trials registered on ClinicalTrials.gov as lead sponsor.
“Juvenescence is a clinical-stage drug development company dedicated to extending healthy lifespan through innovative medicines” (from its website)
No human trials registered on ClinicalTrials.gov as lead sponsor.
“At Loyal, our approach is to help dogs live longer and stay healthier as they age by developing drugs that target the underlying processes that lead to age-associated disease and disability.” (from its website)
No human trials registered on ClinicalTrials.gov as lead sponsor.
“NewLimit is inventing medicines to add healthy years to people's lives.” (from its website)
No human trials registered on ClinicalTrials.gov as lead sponsor.
Jun 2, 2026 · STAT“Longevity startup NewLimit plans to launch its first clinical trial of a liver medicine after raising a staggering $435 million in new funding.” Source ↗
“Targeting the root causes of aging to create life-changing treatments for chronic conditions affecting both companion animals and humans.” (from its website)
No human trials registered on ClinicalTrials.gov as lead sponsor.
“Retro Biosciences develops therapies that meaningfully reverse age-related diseases.” (from its website)
No human trials registered on ClinicalTrials.gov as lead sponsor.
May 22, 2026 · STAT“The company is currently running its first clinical trial — testing a pill designed to enhance the body’s ability to better clear out protein aggregates in patients with Alzheimer’s disease.” Source ↗
We couldn't read a description from its website.
No human trials registered on ClinicalTrials.gov as lead sponsor.
This is general information gathered from the sources listed, not medical advice. Talk to your doctor before starting anything new.
