Effects of Isha Yoga Practices on Health Outcomes: A Systematic Review of Controlled Studies

The global burden of chronic diseases and mental health disorders has intensified the need for holistic interventions such as yoga. Isha Yoga, a comprehensive system integrating physical postures, breathwork, and meditation, has demonstrated preliminary benefits in stress reduction and physiological regulation. This systematic review evaluates the effects of Isha Yoga practices on mental and physical health outcomes in controlled studies. In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, systematic searches were conducted in PubMed, Scopus, Web of Science, and the Cochrane Library from database inception to July 2025. Eligible studies employed controlled designs, including randomised controlled trials (RCTs), non-randomised controlled studies, and cross-sectional comparative studies that evaluated the effects of Isha Yoga practices on health-related outcomes with comparators. Methodological quality and risk of bias were assessed using the Cochrane Risk of Bias 2 tool for RCTs and the Risk Of Bias In Non-randomized Studies - of Interventions (ROBINS-I) tool for non-randomised studies. Due to heterogeneity, a narrative synthesis was performed, grouped by outcomes with subgroups for expertise and dosage. Nine studies were included: three RCTs, four non-RCTs, and two cross-sectional studies. Mental health benefits were consistent, with moderate-to-large reductions in stress (four studies; d=0.27-0.94), anxiety and depression (three studies; d=0.48-1.88), and improvements in well-being and resilience (four studies; d=0.32-0.78). Physiological outcomes demonstrated enhanced heart rate variability (one study; p=0.01-0.02), reduced inflammation and metabolic markers (two studies; p<0.02), and microbiome shifts (one study; p_adj=0.001). Effects were dose-dependent (≥3-4 days per week) and stronger amongst experienced practitioners. Risk of bias was moderate overall; sensitivity analyses confirmed findings. Isha Yoga demonstrates promising mental health benefits and preliminary physical health benefits, with stronger effects observed in sustained practice. Methodological limitations warrant caution. Future large-scale RCTs with active comparators and biomarkers are recommended to confirm efficacy and elucidate underlying mechanisms.