Heavy Metals in Indian Traditional Systems of Medicine: A Systematic Scoping Review and Recommendations for Integrative Medicine Practice

Introduction: Ayurveda and Siddha are two important components of the traditional Indian medicine (TIM). The regulatory mechanisms have been insufficient, and heavy metal toxicity with TIM preparations continues to be a public health nuisance, putting integrated medicine practice in jeopardy. The current study was undertaken to review the potential health hazards of the heavy metal content in the TIM and formulate patient-safety recommendations for integrative medical practice. Materials and Methods: Systematic MEDLINE searches were performed using a combination of relevant MeSH terms and keywords, and case report/series of Ayurveda or Siddha-induced heavy metal toxicity, published in the previous two decades, were included. Risk of bias was assessed with the tool by Murad et al. Results: A total of 220 cases (51 case reports and 14 case series) were found (lead, n = 156; arsenic, n = 11; mercury, n = 47; thallium, n = 1; gold, n = 1; combination of heavy metals, n = 4) after screening for the inclusion and exclusion criteria. Among them, 169 (76.8%) had a low risk of bias, 113 (out of 135 [83.7%] analyzed) contained higher-than-permissible heavy metal content in the drug samples, and the majority showed elevated biological levels of the heavy metals in the body. Conclusion: The heavy metals in TIM are often the result of adulteration or improper manufacturing and prescribing practices, despite national and international guidelines recommending quality standards and protocols for preparing and dispensing TIM. We thus propose multipronged approaches and provide recommendations at various levels, including individual, institutional, national policy decisions essential to establish patient safety of TIM.