Scientific studies on the medicinal properties of guava leaf began in earnest in the 1940’s. According to Xavier Lozoya, who has published numerous papers on guava leaf extract, “reports maintain a tradition of repeating the [same] data each decade, ignoring already published observations. Thus, three main tracks are followed for validation of the curative properties of guava leaves: a) the anti-microbial capacity…confirming its growth-inhibiting effect particularly on Staphylococcus aureus, Escherichia coli, and other common entero-pathogenic cultures; (b) the anti-diarrheic measured as an effect on motility property of intestine; and (c) the sedative effect of some guava extracts measured in animals on locomotor and nervous activity” (20).
Lozoya is telling us that up until recently, the same three “tracks” of studies have been repeated again and again. So, scientific studies have proven beyond doubt that guava leaf has powerful anti-microbial properties, anti-diarrhea properties and it also has a calming (or sedative) effect on the nervous system.
In a review of the scientific literature until 2008, guava leaf extract has also been shown to “exhibit antioxidant, hepatoprotection, anti-allergy, antimicrobial, antigenotoxic, antiplasmodial, cytotoxic, antispasmodic, cardioactive, anticough, antidiabetic, antiinflamatory and antinociceptive activities, supporting its traditional uses” (Gutierrez et. al. 2008). This is quite a list, and I will be discussing each of these conditions and the literature supporting guava leaf’s impact on each condition separately. A link to the abstract of this article, titled Psidium guajava: A review of its traditional uses, phytochemistry, and pharmacology, can be found here at ScienceDirect.com