What did the Tel Aviv HBOT and telomeres study find?

Hachmo et al. (2020) studied 35 healthy adults over age 64. After 60 HBOT sessions at 2.0 ATA, telomere length increased 20-38% in various immune cell types, and senescent cells were reduced by 11-37%. PMID: 33206581. This was a single-center prospective trial without a randomized control group.

Does telomere lengthening from HBOT mean longer lifespan?

No. Telomere lengthening is associated with cellular health and aging biology, but the study did not measure lifespan outcomes. Longer telomeres do not directly translate to longer life or disease reversal. This research is preliminary and these conclusions have not been replicated in large randomized trials.

What are senescent cells and why does reducing them matter?

Senescent cells are cells that stop functioning normally but don't die. They accumulate with age and release inflammatory signals that damage surrounding tissue. Reducing senescent cell burden is an active area of aging research called senolytics. The Hachmo (2020) study's finding that HBOT reduced senescent cells 11-37% is notable but preliminary.

How many sessions did the Tel Aviv study use?

60 sessions at 2.0 ATA, 90 minutes per session, 5 days per week for 12 weeks. This was a clinical-grade protocol at a medical facility — not a home soft chamber. Home chambers at 1.3 ATA were not used in this research.

Is HBOT for anti-aging covered by insurance?

No. Anti-aging is not an FDA-approved HBOT indication. No insurer covers HBOT for telomere lengthening, senescent cell reduction, or anti-aging purposes. This is investigational use paid entirely out-of-pocket.

HBOT and Telomeres: What the Tel Aviv Study Found (and Didn’t Find)

One study drives most of the current interest in HBOT as an anti-aging intervention. Hachmo et al. (2020), published in the journal Aging, found measurable changes in biological aging markers after a course of HBOT in healthy older adults. The findings are real. The interpretations in some marketing are not.

Here’s what the study actually measured, what the results mean, and where the evidence stops.

The Study Design

Hachmo et al. (2020) enrolled 35 healthy adults over age 64. All participants completed 60 HBOT sessions at 2.0 ATA, 90 minutes per session, five days per week over 12 weeks. Sessions were conducted at a clinical facility, not at home.

The researchers measured two primary outcomes:

Telomere length in peripheral blood mononuclear cells (various immune cell types)
Senescent cell percentages in the same cell populations

This was a prospective trial. There was no randomized control group receiving sham treatment.

PMID: 33206581.

What Telomeres Are and Why This Matters

Telomeres are protective caps on the ends of chromosomes. Think of them as the plastic tips on shoelaces. Each time a cell divides, telomeres shorten slightly. Short telomeres are associated with cellular aging, increased disease risk, and reduced cell function. Cells with very short telomeres stop dividing and either die or become senescent.

Telomere shortening is considered one of the hallmarks of aging in current aging biology research. The enzyme telomerase can lengthen telomeres, but telomerase activity declines with age in most cell types.

The study found telomere length increased 20 to 38% across various immune cell populations after 60 HBOT sessions. That’s a notable finding. Most interventions studied in aging research don’t produce telomere lengthening at all.

What Senescent Cells Are

Senescent cells are cells that have stopped dividing and functioning normally but haven’t died. They accumulate with age and secrete inflammatory signaling molecules — the senescence-associated secretory phenotype (SASP) — that damage neighboring healthy cells.

Clearing senescent cells (senolytics) is one of the most active areas of aging research. Drugs like dasatinib and quercetin are being studied in trials for this purpose.

The Hachmo (2020) study found senescent cell counts decreased 11 to 37% in various immune cell populations after HBOT. For a non-pharmaceutical intervention, that’s a meaningful signal.

What the Study Does Not Prove

The findings are interesting and warrant further research. They do not prove:

That HBOT extends human lifespan. No lifespan data was collected. Telomere lengthening in immune cells over 12 weeks doesn’t translate directly to years of life.

That HBOT reverses aging. The study showed changes in cellular aging markers. It didn’t show reversal of clinical aging symptoms, disease, or functional decline.

That everyone will get these results. Thirty-five people at one center is a small, non-randomized sample. Without a control group receiving sham HBOT, the contribution of placebo effect and other factors can’t be isolated.

That home soft chambers replicate this. The study used 2.0 ATA with 100% oxygen at a clinical facility. Home chambers at 1.3 ATA with ambient air produce fundamentally different physiology. No data supports the same telomere effects at home-chamber pressures.

Why Biohackers Care

Bryan Johnson and others in the biohacking community cite this study as supporting evidence for HBOT in anti-aging protocols. The study is legitimate and from a credible research group (Efrati lab, Tel Aviv University). The interest is warranted.

But self-experimenting biohackers using 2.0 ATA clinical sessions at $250 to $450 per session for 60 sessions are spending $15,000 to $27,000 for preliminary outcomes with no replication yet. That’s a significant financial commitment for early-stage evidence.

See our page on Bryan Johnson and HBOT for more on how he incorporates these protocols.

The State of Anti-Aging Research with HBOT

As of early 2026, no large randomized controlled trial has confirmed the Hachmo (2020) findings. The Tel Aviv group (Efrati lab) continues to publish on HBOT and neurological aging, and replication attempts are underway. Active clinical trials may provide more data within the next few years.

Anti-aging HBOT is investigational. Not FDA-approved. Not covered by insurance. Worth watching as research develops — but not worth treating as established medicine yet.

FAQ

What pressure was used in the Tel Aviv study? 2.0 ATA with 100% oxygen, 90 minutes per session, 60 sessions total. This is clinical-grade HBOT, not a home soft chamber protocol.

Can I get these results from a home hyperbaric chamber? The study used 2.0 ATA. Home soft chambers typically operate at 1.3 ATA with ambient air. The telomere research hasn’t been conducted at lower pressures, and the physiological effect at 1.3 ATA is substantially smaller.

Is the Efrati lab credible? Professor Shai Efrati’s group at Tel Aviv University has published extensively in peer-reviewed journals on HBOT and aging. The work is credible and cited by mainstream medical researchers. Preliminary doesn’t mean fraudulent.

How much would 60 sessions of HBOT cost? At $250-$450 per clinical session, 60 sessions runs $15,000-$27,000. This is fully out-of-pocket for investigational use.

Medical Disclaimer: The content on this page is for informational purposes only. It is not medical advice and does not create a doctor-patient relationship. HBOT for anti-aging or telomere lengthening is investigational and not FDA-approved. Consult a licensed physician before starting any hyperbaric therapy program.