Guava leaf, like many other herbs, has an amazing array of qualities, and it seems to be able to do amazing things. It can stop diarrhea and has saved many lives across the world. Especially in impoverished countries, and in regions where modern health care is either not accessible, or it is not affordable (or both). There are constituents in guava leaf that attack pathogens. It’s antibacterial. Guava leaf can regulate blood glucose levels. It can help make you thin! It can even allow you to drink as much as you want and not have (many) repercussions the next day!

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Originally inherited from the Aztec in Mesoamerica, guava leaves have a long history in Guatemala as a useful, and sometimes lifesaving, tool for battling diarrhea and intestinal discomfort.  They are listed alongside 15 other plants in “Plants used in Guatemala for the treatment of gastrointestinal disorders,” published in the Journal of Ethnopharmacology, in 1993.

This paper “reports the in vitro studies [studies done in a petri dish] of the activity of 16 plant extracts against pathogenic enterobacteria (31).  The researchers start out with a list of 408 plants; they narrow the list down to 34 plants which are deemed worthy of further study.  Of these 34 plants, 16 are chosen for “confirmation” of antibacterial activity against E coli, Salmonella enteritidis, and Shigella flexneri pathogens.  Guava leaf (Psydium guajava) turns out to be one of three plants (out of the 16) that inhibits growth of all three kinds of bacteria.

For a majority of these plants, the most effective extraction agent for antibacterial activity is ethanol.  Ethanol extract, acetone extract, and n-hexane extracts of each plant are tested and compared for effectiveness.  For guava leaf, the acetone extract proved most effective for antibacterial activity.

In Guatemala, guava leaf is used for diarrhea, dysentery, stomach pain, leucorrhea (a condition of unusual vaginal discharge), and a variety skin infections.

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Some of the earliest mentions of guava leaf in the Western world appear in the medical journal The Lancet, dating to the early 1800’s, as doctors chronicled their experiences in tropical locales, reporting on indigenous customs they discovered during their travels.  “For my own part,” writes Dr. J Hancock, “I think there is no method better adapted for the successful treatment of fevers in general, than that which is followed by certain tribes of Guiana, which consists of very little besides the use of aromatic vapour-baths and frictions; they take for this purpose the leaves of the guava, lime-tree… bruise and throw them into the bath. A similar practice is pursued by the Creoles of Martinique [for] fever, and with a success much greater than that attending the European practice” (Lancet 1830).  This early example of Western medicine borrowing knowledge from traditional or indigenous medicine is a practice recurring throughout history, and still continues today. Read more