Does Hyperbaric Oxygen Therapy Reverse Aging? Myth vs. Data
TL;DR: No. In the randomized trials we identified, HBOT has not been shown to reverse biological age measured with validated epigenetic clocks. The “age reversal” claim rests on an uncontrolled telomere analysis in 25 older adults, while two randomized trials from the same Israeli center found functional gains (cognition, VO2max), which are not the same thing as slower or reversed aging.
Table of Contents
- The Common Belief: Can an Oxygen Chamber Make You Biologically Younger?
- What Has HBOT Actually Shown in Older Adults?
- What Did Each Study Measure and Find?
- What Cannot Be Claimed From These Studies?
- Why Is One Biomarker Not the Same as Biological Age?
- What Evidence Would a Real Age Reversal Claim Need?
- FAQ
- Conclusion
- References
The Common Belief: Can an Oxygen Chamber Make You Biologically Younger?
Since a 2020 telomere study, hyperbaric oxygen therapy (HBOT) has been promoted in longevity circles with a simple promise: sit in a pressurized chamber, breathe pure oxygen, and your telomeres grow longer while your biological age goes down.
The claim is attractive because it sounds mechanical and measurable. Telomeres are the protective caps on chromosomes, they shorten with age, and a longer number on a lab report feels like proof that the clock was turned back. HBOT is also a real medical procedure with established uses, which lends it credibility that a supplement bottle does not have.
This article checks that promise against what the human studies actually measured. If you have read our breakdown of what the randomized trials show about lowering biological age, the lesson here is the same: the design of a study decides what it can prove.
What Has HBOT Actually Shown in Older Adults?
Almost all of the human evidence behind the anti-aging claim comes from one research program at Shamir Medical Center in Israel, run between 2016 and 2020. Every study used the same protocol: 60 daily sessions, five per week over about three months, breathing 100% oxygen at 2 atmospheres absolute (ATA) for 90 minutes, with 5-minute air breaks every 20 minutes. Participants were independently living adults aged 64 and older.
Three papers came out of that program:
- Hachmo et al., 2020 (Aging): an uncontrolled single-arm analysis of telomere length and senescent immune cells in the HBOT group only.
- Hadanny et al., 2020 (Aging): a randomized controlled trial with a no-treatment control, measuring cognition and brain perfusion.
- Hadanny et al., 2024 (BMC Geriatrics): a randomized controlled trial with a no-treatment control, measuring physical performance (VO2max).
These are not three independent confirmations. Hachmo states that its cohort is the HBOT arm of the larger study registered as NCT02790541, Hadanny 2024 is registered as NCT02790541, and Hadanny 2020 reports the same center, the same period and the same 30/33 arm sizes. They very likely describe overlapping participants. In all three papers, the authors declared that several of them work for AVIV Scientific Ltd and that the senior author is a shareholder (in Hadanny 2024, shareholder and co-founder). These are the authors’ own declared competing interests.
What Did Each Study Measure and Find?
Blood biomarkers: the telomere analysis (uncontrolled)
The study behind the headlines is Hachmo et al. (2020). It was a prospective single-arm analysis, and the authors themselves list “the lack of control group” as a limitation. Of 35 participants assigned to HBOT, 30 completed the course, 25 were included in the telomere analysis and 20 in the senescent-cell analysis. Blood was drawn at baseline, at session 30, at session 60 and 1 to 2 weeks after the last session.
Telomeres were measured as “relative telomere length” by flow-FISH in isolated blood cell subsets, expressed relative to a control cell line. Every percentage below is a within-person change from that person’s own baseline, not a comparison with untreated people:
- B cells: +25.68% ±40.42 at session 30, +29.39% ±23.39 at session 60 and +37.63% ±52.73 one to two weeks after; the repeated-measures effect was significant.
- T helper cells: increases of about 22 to 29% at single time points, but the repeated-measures analysis showed only a non-significant trend (p=0.06).
- NK cells and cytotoxic T cells: increases at some time points, with no additional significant repeated-measures effect after session 30.
- Whole PBMC telomere length: no significant change (p=0.09).
- Senescent cells: senescent T helper cells fell by 37.30% ±33.04 and senescent cytotoxic T cells by 10.96% ±12.59 after HBOT.
Look at the variance. A standard deviation of ±52.73 around a mean of +37.63% means individual responses ranged widely, in a group of 25 people with no untreated comparison. The study measured no epigenetic clock, no functional or clinical outcome, and follow-up ended 1 to 2 weeks after treatment.
Cognition: a randomized trial
Hadanny et al. (2020) randomized 63 adults aged 64 and older; the full-text Table 1 lists 30 in the HBOT group and 33 controls, and the cognitive analysis included 29 versus 32. The primary endpoint, global cognitive function, showed a significant group-by-time interaction in favor of HBOT. The largest effects were in attention (net effect size 0.745) and information processing speed (0.788). A subset (19 HBOT, 20 control) had MRI scans, which showed increases in brain perfusion.
The control group received no intervention, not a sham session. Participants knew which group they were in; outcome assessors were blinded. No telomeres and no epigenetic clock were measured.
Physical performance (VO2max): a randomized trial
Hadanny et al. (2024), registered as NCT02790541, enrolled 70 sedentary adults aged 64 and older; 63 completed (30 HBOT, 33 control). The primary endpoint was VO2max. VO2max per kilogram rose by 1.91 ±3.29 ml/kg/min, a net effect size of 0.455 versus control (p=0.0034). Missing post-tests for several participants were imputed. The authors list a small sample, the lack of a sham control, unknown durability and an unknown optimal protocol as limitations. No telomeres and no epigenetic clock were measured.
| Randomized trial | Participants analyzed | Control | Primary outcome | Result | Epigenetic clock measured? |
|---|---|---|---|---|---|
| Hadanny 2020, Aging | 29 HBOT vs 32 control (cognition) | No intervention, unblinded participants, blinded assessors | Global cognitive function | Significant group-by-time interaction; attention 0.745, processing speed 0.788 | No |
| Hadanny 2024, BMC Geriatrics | 30 HBOT vs 33 control | No intervention, unblinded participants, blinded assessors | VO2max | +1.91 ±3.29 ml/kg/min, net effect size 0.455 (p=0.0034) | No |
True aging endpoints: epigenetic clocks
None of the three Israeli studies measured an epigenetic clock. The only epigenetic-clock signal we found comes from TranslAGE, a database published in Nature Medicine in 2026 (Sehgal et al.). It re-analyzed 51 longitudinal intervention studies with 16 epigenetic clocks, using paired before-and-after tests. One of those studies was a privately run HBOT study; the main text reports no trial registration, and its design and sample size are not stated there, so they remain unknown.
Among the reliable second-generation clocks, HBOT significantly decreased only DunedinPACE, plus the lung-system score of SystemsAge (effect size 0.27). The TranslAGE authors note that sporadic responses of only a few clocks like this may be false positives. It is a single-clock pre/post signal from a study of unknown design, not a demonstration of age reversal.
The broader literature points the same way. A 2025 systematic review in Aesthetic Plastic Surgery (Fisher et al., 15 included articles) concluded that the evidence for HBOT in aesthetics and anti-aging is limited and called for large randomized trials with standardized protocols.
What about safety?
In the two randomized trials, mild middle-ear barotrauma occurred in 4 HBOT participants (13.3%) in Hadanny 2020 and in 3 (11.1%) in Hadanny 2024, and in none of the controls. Hadanny 2020 also recorded changes in visual acuity. HBOT is a medical procedure, and whether it is appropriate for you is a question to discuss with a physician.
What Cannot Be Claimed From These Studies?
| Popular claim | What the data shows | Source and design |
|---|---|---|
| “HBOT lengthens telomeres in all immune cells.” | Significant repeated-measures increase in B cells only; T helper cells a non-significant trend; whole PBMC telomere length not significantly changed. | Hachmo 2020, uncontrolled single-arm analysis, n=25 |
| “HBOT reverses biological age.” | No epigenetic clock was measured in any of the Israeli studies. | Hachmo 2020; Hadanny 2020; Hadanny 2024 |
| “The results were proven against a control group.” | The telomere results were within-person changes with no control group. | Hachmo 2020, authors’ own stated limitation |
| “Better cognition and fitness prove slower aging.” | They are functional improvements versus no treatment, not measures of aging rate. | Hadanny 2020 and 2024, randomized, no sham |
| “An epigenetic clock confirmed it.” | One clock (DunedinPACE) moved in one study of unknown design; the authors warn such signals may be false positives. | Sehgal 2026, TranslAGE re-analysis database |
Put plainly: the telomere data cannot show that HBOT lengthened telomeres compared with what would have happened anyway, because nobody untreated was measured. It cannot show that the change lasted, because follow-up stopped after 1 to 2 weeks. And it cannot show that any person became biologically younger, because biological age was never measured with a validated clock.
The randomized trials are stronger, but they answer different questions. They show that, in healthy adults aged 64 and older, 60 sessions of HBOT improved some cognitive scores and VO2max compared with doing nothing. Without a sham control, part of those gains could reflect expectation or the daily routine of attending sessions. Whether the benefits persist, and whether they apply to younger or less healthy people, is unknown.
In the randomized trials we identified, HBOT has not been shown to reverse biological age measured with validated epigenetic clocks.
Why Is One Biomarker Not the Same as Biological Age?
Biological age is an estimate of how far the body has aged compared with its calendar age, built from many signals at once. A change in one blood marker, or in one measure of function, does not move that estimate on its own.
Telomere length is a particularly weak stand-in. Measurements are noisy, they differ by cell type, and the relationship between telomere length and lifespan is not straightforward, as the case covered in the telomere paradox in a 117-year-old shows. A temporary rise in relative telomere length in a few immune-cell subsets is a laboratory finding, not a younger body.
Functional gains belong in yet another category. Improving VO2max or attention scores matters for daily life, and exercise does both too, but neither measure tells you whether the underlying rate of aging changed. Even validated biological age tests disagree with each other, which is why we compared them in our biological age test comparison.
What Evidence Would a Real Age Reversal Claim Need?
A credible claim that HBOT reverses or slows aging would need, at minimum:
- A randomized trial with a sham control, such as low-pressure air in the same chamber, so expectation and routine are separated from the oxygen itself.
- Pre-registered aging endpoints measured with validated epigenetic clocks, analyzed as a comparison between groups rather than within-person change.
- Independent replication in a separate cohort, by researchers without a financial stake in HBOT clinics.
- Long follow-up, showing that any change lasts months to years after the sessions end.
- Hard outcomes over time, such as disease incidence, disability or mortality, not only biomarkers.
- Broader populations than healthy adults aged 64 and older, with safety reported in full.
None of the studies above meets more than one or two of these points. Until a trial does, HBOT for anti-aging remains a hypothesis. For comparison, the effects of other interventions tested in randomized trials with epigenetic clocks have so far been small; they are summarized in our review of the biological age trials.
If you want the full system behind how I evaluate claims like this one, I wrote it all down in The MVHK Protocol.
FAQ
Does hyperbaric oxygen therapy reverse aging?
No human trial has shown it. In the randomized trials we identified, HBOT has not been shown to reverse biological age measured with validated epigenetic clocks. The age reversal claim comes from an uncontrolled telomere analysis in 25 older adults.
Does HBOT lengthen telomeres?
One uncontrolled study found within-person increases in relative telomere length in some blood-cell subsets, significant over time only in B cells. Whole PBMC telomere length did not change significantly, and there was no untreated comparison group.
What did the randomized HBOT trials in older adults find?
Two trials from the same Israeli center found improved global cognition and VO2max after 60 sessions compared with no treatment. Neither used a sham control, and neither measured telomeres or an epigenetic clock.
Are the HBOT aging studies independent of each other?
Very likely not. All three report the same center, period and protocol and link to trial NCT02790541, so they probably share participants. The authors also declared employment at, or shares in, AVIV Scientific Ltd.
Is HBOT safe for older adults?
In the two trials, mild middle-ear barotrauma affected 13.3% and 11.1% of HBOT participants and none of the controls; visual acuity changes were also recorded in one trial. HBOT is a medical procedure to discuss with a physician.
Did any epigenetic clock change after HBOT?
In the TranslAGE database, one privately run HBOT study of unknown design showed a decrease in DunedinPACE only, among reliable second-generation clocks. The authors warn that such isolated signals may be false positives.
Conclusion
HBOT has produced real but narrow findings in healthy adults aged 64 and older: better cognitive scores and higher VO2max than no treatment, from one research program with overlapping participants and declared commercial ties. The telomere result that launched the age reversal story was an uncontrolled, short within-person change in selected immune cells. No validated epigenetic clock has shown HBOT reversing biological age in a randomized trial.
Further reading: How to lower biological age: what the trials actually show, biological age tests compared, and the telomere paradox in a 117-year-old.
References
- Hachmo Y, et al. Aging (Albany NY). 2020. Prospective single-arm analysis (HBOT arm of NCT02790541). PMID: 33206062. PMC7746357.
- Hadanny A, et al. Aging (Albany NY). 2020. Randomized controlled trial, cognition. PMID: 32589613. PMC7377835.
- Hadanny A, et al. BMC Geriatrics. 2024. Randomized controlled trial (NCT02790541), physical performance. PMID: 38961397. PMC11220959.
- Fisher SM, et al. Aesthetic Plastic Surgery. 2025. Systematic review, 15 included articles. PMID: 39733047.
- Sehgal R, et al. Nature Medicine. 2026. TranslAGE re-analysis database of 51 longitudinal intervention studies. PMID: 42629466. PMC13577923.
