The effects of mind-body therapies on the immune system: meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 24988414 · doi:10.1371/journal.pone.0100903
What was done
Authors conducted a systematic review and random-effects meta-analysis of randomized controlled trials (RCTs) indexed in MEDLINE, CINAHL, SPORTDiscus, and PsycINFO through September 1, 2013. Included studies were English-language RCTs evaluating at least 4 weeks of mind-body interventions (Tai Chi, Qi Gong, meditation, or Yoga) reporting immune outcomes. Data were synthesized using standardized mean difference (ES) across inflammatory measures (18 studies), anti-viral immunity (7 studies), and cell counts (14 studies).
What was found
Across 34 RCTs (39 articles, 2,219 participants) evaluating 7 to 16 weeks of mind-body practices: - C-reactive protein (CRP): Statistically significant reduction (ES 0.58; 95% CI, 0.04 to 1.12). - Interleukin-6 (IL-6): Small, non-significant reduction (ES 0.35; 95% CI, -0.04 to 0.75). - Tumor necrosis factor-alpha (TNF-α): Negligible effect (ES 0.21; 95% CI, -0.15 to 0.58). - CD4 counts: Negligible effect (ES 0.15; 95% CI, -0.04 to 0.34). - Natural killer (NK) cell counts: Negligible effect (ES 0.12; 95% CI, -0.21 to 0.45). - Anti-viral immunity: Some evidence indicated increased immune response to vaccination.
Why it matters
This review provides aggregate clinical trial evidence that mind-body modalities can modestly reduce circulating systemic inflammatory markers like CRP and may improve vaccine responsiveness, but do not meaningfully alter resting immune cell counts.
Limits
The literature search was restricted to English-language publications. Confidence intervals for inflammatory markers were wide, and findings for IL-6 and TNF-α did not reach statistical significance. Different intervention types (Tai Chi, Qi Gong, meditation, Yoga) and durations were pooled together, and clinical infection or disease endpoints were not reported.
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