Scientific evidence

As a traditional medicine, many ayurvedic products have not been tested in rigorous scientific studies and clinical trials. The National Center for Complementary and Alternative Medicine states that "most clinical trials of Ayurvedic approaches have been small, had problems with research designs, lacked appropriate control groups, or had other issues that affected how meaningful the results were."

In India, research in Ayurveda is largely undertaken by the statutory body of the Central Government, the Central Council for Research in Ayurveda and Siddha (CCRAS), through a national network of research institutes. However, "even staunch advocates of Ayurveda like cardiologist Dr. M.S. Valiathan...admit that 'clinical studies that would satisfy the liberal criteria of WHO World Health Organisation have been alarmingly few from India, in spite of patients crowding in Ayurvedic hospitals"'.

Despite these misgivings, some ayurvedic products, mainly herbs used for phytotherapy, have been tested with promising results. Turmeric has been used in Ayurvedic medicine since 1900 BC, and its derivative curcumin appears to have beneficial properties. Tinspora cordifolia has been tested. Among the medhya rasayanas (intellect rejuvenation), two varieties of sage have been been tested; one improved word recall in young adults, and another improved symptoms in Alzheimer's patients. In some cases Ayurvedic medicine may provide clues to therapeutic compounds. For example, derivatives of snake venom have various therapeutic properties. Many plants used as rasayana (rejuvenation) medications are potent antioxidants. Neem appears to have beneficial pharmacological properties as well.

A systematic review of Ayurveda treatments for rheumatoid arthritis concluded that there was insufficient evidence, as most of the trials were not done properly, and the one high-quality trial showed no benefits. A review of Ayurveda and cardiovascular disease concluded that while the herbal evidence is not yet convincing, the spices are appropriate, some herbs are promising, and yoga is also a promising complementary treatment.