Although laboratory experiments suggest it is possible that some substances in Ayurveda might be developed into effective treatments, there is no evidence that any are effective as currently proffered.[11] Ayurveda medicine is considered pseudoscientific.[12] Other researchers consider it a protoscience, or trans-science system instead.[13][14] Close to 21% of Ayurveda U.S. and Indian-manufactured patent medicines sold through the Internet were found to contain toxic levels of heavy metals, specifically lead, mercury, and arsenic.[15] The public health implications of contaminated metals in India is unknown.[15]
Some scholars assert that Ayurveda originated in prehistoric times,[16] and that some of the concepts of Ayurveda have been discovered since the times of Indus Valley Civilization and earlier.[17] Ayurveda significantly developed during the Vedic period and later some of the non-Vedic systems such as Buddhism and Jainism also developed medical concepts and practices that appear in the classical Ayurveda treatises.[17][18] Humoral balance is emphasized, and suppressing natural urges is considered unhealthy and claimed to lead to illness.[19] Ayurveda names three elemental substances, the doshas (called Vata, Pitta and Kapha), and states that a balance of the doshas results in health, while imbalance results in disease. Ayurveda has eight canonical components, which are derived from classical Sanskrit literature. Some of the oldest known Ayurvedic texts include the Suśrutha Saṃhitāand Charaka Saṃhitā, which are written in Sanskrit. Ayurveda practitioners had developed various medicinal preparations and surgical procedures by the medieval period.[20]
