Saffron and its active ingredients against human disorders: A literature review on existing clinical evidence

Saffron, the stigmas of Crocus sativus L., has been mentioned extensively in the traditional reference texts as a herbal medicine. Many clinical trials have been conducted on this valuable herbal substance and its main constituents following numerous cellular and animal assessments. In the present review, we have collected almost all of these clinical studies to clarify how much knowledge has clinically been achieved in this field so far and which scientific gaps are needed to be filled by more studies. A comprehensive literature review was conducted through a two-round search. First, we performed a general search for identifying the human disorders against which saffron was studied. Then, we searched specifically for the combination of saffron keywords and each disease name. Scientific databases including Scopus, PubMed, and Web of science were used for this search. Studies were collected through electronic databases from their inception up to August 2021. The largest number of these clinical studies represent the investigations into saffron efficacy in different neurological and mental disorders, particularly depression. This substance has clinically revealed significant protective effects against various types of depression, age-related macular degeneration, and allergic asthma. In some cases, such as sexual dysfunction, cognitive and metabolic disorder, the effects of saffron are still clinically open to dispute, or there are limited data on its positive influences. Overall, saffron and its constituents have promising effects on human disorders; however, it needs more clinical evidence or meta-analyses to be confirmed.