Curcumin's Unique Anti Cancer Properties
Turmeric was originally cultivated in the tropics, but now thrives in other tropical regions around the world. It has large dark green leaves that are erect and oblong in shape. The leaves are pointed at the apex and broad near the base. It is a herbaceous perennial plant of the ginger family and has red-orange coloured rhizomes which grow beneath the foliage. During the dry season, the stems and leaves dry up and the rhizome remains dormant in the soil. It has a long history of being used in both food and medicine, playing a major role in Ayurvedic medicine for nearly 6000 years. It has been used to purify the blood and to treat a number of illnesses such as indigestion, liver and gall bladder diseases, arthritis, rheumatism, even colds and flu. Raw turmeric applied to the skin is effective in treating inflammation, infection, bruises and sprains. Since the discovery of turmeric’s antioxidant phenolic compounds and the protection that these compounds provide against free radicals, this spice is now viewed as much more than just a food colourant or yellow dye. Turmeric’s potential use in cancer prevention and the treatment of HIV infections is now the subject of intense laboratory and clinical research (Majeed, Badmaev and Murray 1996).
There is an increasing awareness of plant-derived substances playing a vital role in preventing cancer. These plant-based substances are affordable, easily available and more importantly, most have little or no toxicity. There are more than 1000 various potential agents which may have chemopreventive properties and only about a few dozen were moved to clinical trials. One such agent is called Curcumin, which is present in the spice, Turmeric, is being studied for its cancer prevention properties.
Studies into chemopreventive agents can be categorised into different groups according to their mechanism of anticancer effect or mode of action, namely, carcinogen-blocker, antioxidant and anti-proliferative. Curcumin surprisingly has all three properties and belongs to all three classifications. It seems to play a role in blocking every stage of cancer transformation, proliferation and invasion. It may even help before carcinogens even get to our cells.
In a study in 1987, Nagabhushan, Amokar, et al. investigated the effects of Curcumin on the mutagenicity (the DNA’s mutating ability) of several toxins. The study found that Curcumin is anti-mutagenic against several mutagens or other cancer-causing substances. However, this study was in vitro. How about its effect in people? It is not that we are able to expose a group of people to nasty carcinogens, give half of them turmeric and see what happens… unless we can test it on smokers. These people have carcinogens coursing through their veins. In a study by Kalpagam, Kamala, et.al., in 1992, they took a group of smokers, collected their urine and poured the urine sample into bacteria. They measured the number of mutations that happened to the bacteria as a result of their exposure to the urinary mutagens. The urine of non-smokers caused far fewer DNA mutations compared to smokers. They then had the smokers take turmeric for a month… the result was dumbfounding. Thirty days after the smokers took turmeric, the number of mutations decreased by half. We need to take note that the smokers in the study did not take a special health supplement with concentrated curcumin. They only took plain turmeric, the stuff one can buy in the supermarket, for approximately a teaspoon a day. The study concluded that dietary turmeric is an effective anti-mutagen and can be used to prevent cancer.
The anti-cancer effects of curcumin stems from a few mechanisms but mainly on its involvement in the programmed cell death regulation. Of the 13 trillion cells in our body, all these cells are turned over every 100 or so days, which means that there are about 100 billion cells being killed off daily in a process called apoptosis or pre-programmed cell death. When we were still developing in our mother’s womb, we all had webbed feet and hands. However, because of the pre-programmed cell death, we now have non-webbed fingers and toes. Some cells during our lifetime do not die when they are supposed to, like cancer cells, which somehow turns off their suicide genes. One of the ways curcumin kills off cancer cells is by reprogramming the self-destruct mechanism back into the cancer cells. One pathway curcumin helps in cancer prevention is through the pigment in curcumin which makes it yellow that upregulates the death receptor. However, one thing we need to note is that curcumin tends to leave normal cells alone and kills a wide variety of tumour cell types through different mechanism of action. Since curcumin affect different mechanisms of cell death, it could mean that cancer cells may not easily develop resistance to curcumin-induced cell death, like they do in most chemotherapy.