A literature search was conducted on Medline for research articles relating guava (Psidium guajava) to cancer, in order to determine any potential anticancer activity. The keyword "guava was used in combination with cross-referencing (1952 to September, 2010). A total of 373 articles on guava resulted of which 12 were related to cancer. These were then categorized into 1) seven studies on in vitro cancer cell line studies with leaf extracts, 2) five studies on in vitro studies with fruit extract, and 3) one in vivo mouse study. The majority of remaining articles covered chemical constituents and potential bioactives related to anticancer activity found in guava leaves, fruit and bark. Our review revealed that guava extracts (primarily leaf) may have anti-cancer activity, but this is based on a very limited number studies. There was only one study testing guava fruit extract against the proliferation of cancer cell lines. The one in vivo study on mice suggested that a combination bark, leaf and root extract inhibited growth of B16 melanoma cells. Further studies need to confirm the potential antiproliferative activity of guava leaf (or its oil) extracts, but more importantly, if such activity exists in the fruit, which is the part of the plant that is consumed.
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