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!
“Beneficial effects of Psidium guajava leaf extract on diabetic myocardium,” an article Published in Experimental and Toxicologic Pathology.
This article – which was especially technical – discusses guava leaf as having beneficial effects on diabetic myocardium, a cardiac complication stemming from diabetes. The authors state “the aim of the present study was to evaluate the antiglycative as well as cardioprotective role of P. guajava extract in diabetic animal models” (91). A serum protein as cardiac isoform α-2 macroglobulin (cardiac α-2M) was suggested to be involved in the development of cardiac hypertrophy in rats.
“Diabetic complications often arise “as a result of non-enzymatic protein glycation which leads to the formation of advanced glycation end products (AGE’s). The non-enzymatic condensation reaction between the reducing sugars, such as glucose and the amino side chains in proteins (also called Maillard reaction or glycation) has been shown to play an important role in the development of chronic complications of diabetes mellitus” (91). Since guava leaves have been shown to help combat the formation of AGE’s, they thought they would see if a guava leaf extract would help keep the rats who had diabetes from forming these cardiovascular complications.
Using rats as models, the scientists induced diabetes by a “single intraperitoneal (body cavity) injection of STZ (strdissolved in citrate buffer…for three days (92). After the three day period, only rats with fasting blood glucose level above 200mg/dl were considered diabetic and included in the diabetic model.
As the abstract states: “Daily administration of the extract for a period of one month significantly decreased the blood glucose, glycated hemoglobin and fructosamine levels in a dose dependent manner, and the authors conclude that “These findings support that the administration of PGEt [guava leaf extract] extract may be beneficial for preventing cardiovascular complications associated with diabetes.”
I’ve been working to gather the latest research published on guava leaf extract, and am in the “digestion” process currently – sounds bad, but it’s true. It takes a bit of time for me to read, and re-read the studies to ensure that I can report accurately on them. The latest one I’ve been reading is “The Beneficial Effects of Psidium guajava leaf extract on diabetic myocardium,” out of Experimental and Toxicologic Pathology. I realize that it’s been a while since I’ve posted on a study, but there is more to come, I promise. Look for the full write-up tomorrow.
Researchers in Nigeria have found that guava leaf, in combination with other herbs are useful for treating hypertension and other stroke-related maladies. Read the article here.
Many of you have been writing to ask how to make guava leaf tea, so I figured I would make it a new post. There are two methods available when making medicinal herbal teas: Infusions and Decoctions. Infusions are made by starting with boiling water, and letting the herbs soak for 10-20 minutes. To make an herbal decoction, you add your herbal material to cold water, heat it to boiling, then simmer for 20 minutes or more. Decoctions are more often used with root and bark material because medicinal qualities are more difficult to extract.
For guava leaf tea, you can use either method – to ensure the maximum amount of phytochemicals are extracted, simmer for a minimum of 10 minutes. If using dried leaves, add a couple teaspoons per each 8oz water to start, then alter to personal taste. If using fresh leaves you need to add more (maybe 2-4tsp), as the leaves will not be as concentrated and still contain a great deal of water.
These methods may be used for a variety of medicinal teas, but be sure to research your ingredients. Guava leaf has not been shown to have any toxicity, so making a very strong guava leaf tea is ok. The same cannot be said for all herbs. As always, make sure to discuss all herbal uses with a medical professional to asses medication interactions and health concerns.
Cheers to your health, everyone, and I appreciate your comments and questions. Keep them coming!
In October, the Bangkok Post ran an article suggesting people use guava leaves, along with mangosteen skin, the outer part of makham pom (Indian gooseberry), si siad (Acacia catechu) trunk, maak or betel fruit, and phlu leaves to help prevent fungal infection following the worst flooding in Thailand’s history. Read the article here.
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.
To access this article, please click here.
According to Indian folklore, “it is believed that the leaves of this plant [guava] can cure jaundice within three days” (305). The use of guava leaves is reported to be widespread in the Mangalore district of Karnataka, in Southwest India, for the cure of jaundice. Scientists in the area decided to verify the use of guava leaves for jaundice and other liver diseases by conducting a study on the hepatoprotective (liver protection) properties of guava leaves.
The study on the hepatoprotective effects of guava leaf extract was conducted at the Krupanidhi College of Pharmacy in Bangalore, India. Researchers collected fresh leaves from guava trees in the Koramangala area in Bangalore. They crushed them, and boiled the leaves in water for one hour. They filtered out the solids, and evaporated the water, leaving a powdered guava leaf extract. Rats were used as study subjects.
Analysis of the extract showed that it contained carbohydrates, tannins, flavanoids, saponins, steriods, protiens and amino acids.
Researchers found that the extract showed good liver protective activities; the effect produced by the higher doses of guava leaf extract (500mg/kg) was similar to that produced by Silymarin, a well-known hepatoprotective agnet. Furthermore, the guava leaf extract prevented an increase in liver weight in rats, something Silymarin does not do.
“In conclusion,” the researchers stated, “the aqueous extract of Psidium guajava Linn. leaves [guava leaves] showed good hepatoprotective activity in CCI4 induced acute and chronic liver damage, PCM induced liver damage and TAA induced liver necrosis. The hepatoprotective activity may be due to the antioxidant effect of the plant” (310). In other words, guava leaves can help protect the liver. Guava leaf tea or guava leaf extract seems to be able to help prevent damage, or help to treat damage already done.
For a link to the full article, please click here.
In the journal Nutrition and Cancer, an article on the “Action Mechanism and Signal Pathways of Psidium guajava L. Aqueous Extract in Killing Prostate Cancer LNCaP Cells” was published in 2010. The study comes out of Taiwan, a country which makes frequent use of guava leaves for a variety of ailements.
In the article, an ”aqueous extract of Psidium guajava L budding leaves (PE) has been shown to possess anti-prostate cancer activity in a cell line model” (260). The researchers reported that they were drawn to study guava leaves’ effect on prostate cancer cells after conducting a study which showed that guava leaves were “potent anti-glycative agents” (261); this action was ascribed to the unusual free radical scavenging and anti-oxidative capabilities of guava leaf polyphenols. The effects of glycation can result in the formation of irreversible advanced glycation end products (AGE’s), which are associated with many progressive diseases and can also trigger cancer formation. Since guava leaves showed strong anti-glycative properties, the scientists chose to study the leaves’ action against an abundant form of prostate cancer, LNCap: Lymph node-metastasis prostate cancer.
They performed tests both in vitro (petri dish) and in vivo (in mice). In vitro, they found that guava leaves were cytotoxic on the cancer cells, and that the leaves ”arrested cell cycle of LNCaP cells…[guava leaves] inhibited LNCaP cell growth and proliferation by preventing the cells from entering the S phase, and…TUNEL assay also confirmed the apoptic mechanism induced by [guava leaves]” (265).
In vivo, “although no significant difference in body weight was observed among the tumor-implanted [mice], the size of the tumors in the untreated mice was much larger when compared to tumor sizes in the guava leaf-treated mice at week 6 of the study.
“Conclusively,” the authors state, “[guava leaf] is a potent anticancer agent, acting through both cytotoxic and apoptotic action mechanisms; therfore, it [can feasably be used] as a potential adjuvant anti-prostate cancer therapy, in particular, for anti-androgen-responsive PCa” (268).
Click here for access to the full article.
Active.com lists guava fruit as a superfood alongside sardines, blueberries and flaxseed.