Hachmo · Aging 2020 · Prospective single-arm trial · n=35

Hyperbaric oxygen therapy increases telomere length and decreases immunosenescence in isolated blood cells: a prospective trial.

Cited 71 times in the scientific literature.

Level 4 - case-series / case-control

Prospective single-arm interventional study without a control group

PubMed 33206062 · doi:10.18632/aging.202188 · record verified 2026-08-28

What was done

Thirty-five healthy, independently living adults aged 64 and older received 60 daily sessions of hyperbaric oxygen therapy (HBOT). Whole blood samples were drawn at baseline, at the 30th session, at the 60th session, and 1–2 weeks after the final session to assess telomere length and senescence markers in isolated peripheral blood mononuclear cell (PBMC) subsets (T helper, T cytotoxic, natural killer, and B cells).

What was found

Telomere length increased by over 20% across T helper, T cytotoxic, NK, and B cells following HBOT. The largest telomere increase occurred in B cells: +25.68% ± 40.42 at session 30 (p=0.007), +29.39% ± 23.39 at session 60 (p=0.0001), and +37.63% ± 52.73 post-HBOT (p=0.007). Senescent T helper cells decreased by -37.30% ± 33.04 post-HBOT (p < 0.0001), and senescent T cytotoxic cells decreased by -10.96% ± 12.59 (p = 0.0004).

Why it matters

This study provides initial human exploratory data suggesting that intermittent hyperoxic exposure may alter cellular markers of aging, specifically telomere dynamics and senescent cell clearance in immune subsets.

Limits

The trial lacked a control or sham-treatment group, leaving open the possibility of confounding, time-dependent drift, or assay batch artifacts. The sample size was small (n=35), reported standard deviations were wide (often exceeding the mean effect), and the abstract does not assess whether these cellular changes translate into functional or clinical health outcomes.

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