If you like Tom Yum Gung soup, a Thai cuisine favourite, you probably enjoy the flavor and aroma of lemongrass. It’s a stalky plant with a lemony odour, widely used in Asian dishes. Much of the fragrance is due to citral, which actually is a mixture of two very closely related compounds, geranial and neral. Many perfumes use citral as an ingredient, but some people are now looking to citral to do more than tantalize their taste buds or odour receptors. They’re hoping a tea made from lemongrass can help them fight cancer.
The seed for that idea was planted by a study carried out at Ben Gurion University in Israel that showed citral to have anti-cancer properties in the laboratory. A research group led by Dr. Yacob Weinstein found that certain types of cancer cells, such as those responsible for blood cancers like leukemia, when treated with citral, underwent apoptosis, which is basically programmed cell death. Normal cells were unaffected by the chemical. These findings were published in Planta Medica, a peer-reviewed journal that highlights studies on herbal medicine. As one might expect such a study is great fodder for the lay press and before long articles appeared about how lemongrass could prompt cancer cells to commit suicide. Cancer patients soon were besiegedlocal growers for fresh lemongrass in order to make a brew that would mimic the one used by the researchers. You didn’t need mounds of the stuff, the concentration of citral in the experiment could be achieved by boiling about a gram of lemongrass in a cup of water. Many cancer patients who heard the lemongrass story began to drink several glasses of lemongrass tea a day. Marketers jumped at the chance to make easy money and citral supplements began to appear. “Therapeutic herbal drink for good health,” one company claimed for its product, referencing the Israeli study in its literature. Emails began to circulate about a secret remedy that could cure cancer, which of course the pharmaceutical industry was trying to suppress to protect its profits for its ineffective chemotherapeutic drugs. The secret of course was lemongrass tea, or some citral based dietary supplement. Now for a dose of reality. First of all, the only type of cancer cells studied were the so-called hematopoetic ones. No extrapolation can be made to any other kind of cancer. And while the concentration of citral in the tea may be the same as in the solution in which the cancer cells were immersed, the citral that makes it into the bloodstream is immediately diluted by the blood. Nobody has any idea about how much lemongrass tea would have to be consumed to achieve a concentration of citral in the blood that could cause cell death. Indeed, nobody even knows if citral concentrations can build up in the blood. If we go by rat studies, they can’t. When citral is administered to rats, it disappears from the blood within five minutes. But before citral is broken down, it can have an effect on levels of glutathione, one of the body’s natural detoxicating compounds. Glutathione, for example, plays a role in reducing the side effects of cisplatin, a drug used in cancer treatment. Citral also has been shown to activate some liver enzymes that break down drugs, implying that citral may interfere with various drugs.
What this all means is that it is not yet time to jump on the lemongrass bandwagon. The junkheap of cancer treatments is piled high with substances that showed some potential in a test tube experiment but never panned out for human use. While it may not be wise for anyone undergoing chemotherapy to start guzzling lemongrass tea, there is no evidence that it presents any sort of risk to healthy people hoping to guard against cancer. Of course there is no evidence that it does protect against the disease either. That is being investigated though. Thai and Japanese researchers are looking into the chemistry of Tom Yung Gung soup because preliminary experiments have shown that it may have some anti-cancer effects. It will be interesting to see where that research goes, given that Thais have a much lower incidence of digestive tract cancers than other people. And that soup has something else going for it. It tastes good.