We are now finding out that many herbs and food components are important in our diet to promote health and prevent cancer.

Extracts of Lemon Grass Aid in Cancer Prevention

It is becoming widely accepted that dietary factors play a key role in the risk of colon cancer, with many factors increasing the risk while other factors decrease the risk. Lemon grass (Cymbopogon citratus Stapf), whose leave buds and stems are often used in oriental or Thai cooking is one dietary factor recently found to have an inhibitory effect on the development of colon cancer. In a recent study, an extract of lemon grass was shown to inhibit DNA adducts and aberrant crypt foci in the rat colon caused by the known carcinogen, azoxymethane (AOM). DNA adducts are formed when a carcinogen binds to the DNA. This type of DNA damage prevents the correct duplication of the DNA that is necessary for cell growth and division. Formation of these adducts is recognized as one of the earliest steps in the formation of cancer by a chemical carcinogen. An aberrant crypt foci refers to an area of abnormal looking cells which will eventually give rise to a tumor. By looking at these early markers that occur long before tumors actually form, scientists are able to do short term screening of chemopreventive agents, rather than waiting until tumors actually form.

In these experiments, rats were given lemon grass extract prior to injection of an agent known to cause colon cancer, azoxymethane (AOM). At various times afterward, rats were examined for known cancer markers including DNA adducts and crypt foci. Rats given 0.5 g/kg and 5 g/kg of lemon grass extract had 40 and 78% fewer DNA adducts caused by AOM than rats not given lemon grass extract. Likewise, rats given 0.5 g/kg and 5 g/kg lemon grass extract had 61 and 68% fewer aberrant crypt foci caused by AOM than the rats not receiving lemon grass extract.

The protective effects of lemon grass may be due to antioxidant activity found in it, or to its ability to inhibit beta-glucuronidase activity. This enzyme allows the carcinogen AOM to be taken up by the intestines, thus by inhibiting the enzyme, less AOM is taken up by the intestines to have an effect. Active ingredients that have previously been identified in lemon grass oil include citral, geraniol, methyl heptenon and beta-myrcene. These studies suggest that lemon grass extract may be useful in preventing colon cancer.

Cindy L. A. Jones, Ph.D.
Ref: Suaeyun, Ratchada, Kinouchi, T., et al, Inhibitory effects of lemon grass (Cymbopogon citratus Stapf) on formation of azoxymethane-induced DNA adducts and aberrant crypt foci in the rat colon. Carcinogenesis 18:9449-955, 1997.