The Spice of Life
Unlocking the Power of CurcuminSeptember 2001
By John C. Martin
Imagine if the key to disease prevention was as close as your kitchen shelf. It's not the product of someone's imagination, but the product of years of medical research. Scientists are beginning to take notice of a well-known spice as a potent new preventive therapy against disease, especially cancer.
Cancer takes the lives of more than 1,500 people a day—over 5 million since 1990—and is the second leading cause of death in the United States.1
While those statistics are staggering, the medical community is maintaining its focus on mechanisms behind the disease and discovering new, potentially effective methods of treating it. A similar emphasis is placed on prevention, as more and more scientists attempt to uncover the mystery behind ‘carcinogenesis,’ particularly at the genetic level.
What is drawing the attention of medical oncologists and researchers these days is a substance known as curcumin, a naturally occurring yellow pigment found in the spice turmeric, which is part of the ginger plant family. Turmeric is widely consumed in its countries of origin not only as a spice, but as a medicine for the treatment of a variety of illnesses. It was long ago used as an anti-inflammatory among Indian practitioners.2
Today, curcumin is showing a much broader potential. Not only does the extract work as an antioxidant and anti-inflammatory, but a series of studies in the past four years, focusing on cancer at the cellular level, reveals some exciting findings. For one thing, research is discovering that curcumin is a powerful carcinogenic inhibitor, slowing cancerous cell proliferation by inducing apoptosis, a pre-programmed set of processes within a cell that results in its death.
Curcumin targets cancer proliferation
In two recent studies, scientists at New York’s Columbia University researched curcumin’s therapeutic potential against prostate cancer. In one case last year, the scientists discovered that curcumin had a powerful ability to induce apoptosis and inhibit prostate cell proliferation in vitro by interfering with the cells’ protein signaling pathways that typically begin the growth process.3 Just recently, the researchers extended those findings to determine if they could achieve similar results in an animal model.4 In their latest study, the researchers found that prostate cancer cells that had been injected subcutaneously into mice, which had been fed a diet of 2% curcumin for six weeks, were unable to develop extensively and underwent significant apoptosis. “Curcumin could be a potentially therapeutic anti-cancer agent, as it significantly inhibits prostate cancer growth… and has the potential to prevent the progression of this cancer to its hormone refractory state,” the study authors concluded.
Yet prostate cancer is not curcumin’s only target. Other cancer investigations have drawn similarly powerful conclusions about this intriguing substance.
A study this past spring at Wayne State University investigated the effect of curcumin on certain gastrointestinal and colon cancers in the lab.5 Several immunoblot analyses demonstrated that curcumin blocked cell proliferation and induced apoptosis in both gastrointestinal and colon cancer cell lines.
A Chinese study published five years earlier found apoptosis is the result when curcumin is introduced to certain skin, colon, kidney and liver cancer cells, either in cultures or in mouse embryo fibroblasts—large, flat oval cells found in connective tissue and inherent in the formation of fibers.6
Other studies using rodents found curcumin is effective in reducing skin inflammation, inhibiting formation of edemas—an abnormal accumulation of cellular fluid, resulting in swelling—and inhibiting skin tumors when the substance is applied topically7 or orally in concentrations of either 0.2% or 1%.8
Curcumin has had similar effects on other types of cancer. When Polish researchers last year assessed the potency of the extract on lymphoid cells—those found in tissues comprising the lymph nodes— apoptosis resulted, although apoptotic symptoms were uniquely different in the various cells tested, the scientists reported.9
To determine just how effective curcumin might be as an anticarcinogenic agent, it was compared to other compounds and plant extracts in fighting human oral squamous carcinoma.10 Cell lines were grown in vitro for 72 hours, then the number of cells were counted to determine proliferation and growth. The researchers found that curcumin was “considerably more potent” compared to plant phenolics genistein and quercetin in inhibiting this type of cancer. Only cisplatin, a platinum-based substance also tested in the study, was found to be more effective.
Still more research focused on the effect of curcumin on the development of pulmonary fibrosis by testing a group of rodents.11 Scientists in India induced the lung disorder in rats, while giving them dosages of curcumin both 10 days prior and then daily throughout the experiment. Remarkably, curcumin demonstrated its powerful anti-inflammatory and anti-fibrotic effect in each rat studied.
Even breast cancer apparently cannot avoid the power of this extract, which inhibits the growth of breast tumors that result from exposure to environmental estrogenslike chemicals and pesticides, when used in combination with isoflavonoids. Scientists found the curcumin combination inhibited the growth of estrogen receptor-positive cancer cells in a test tube up to 95%.12
The how’s and why’s
What exactly is the mechanism behind curcumin’s ability to counteract such a wide array of cancer progression? For several years, medical research focusing on cancer causation has centered on the notion of angiogenesis, the natural blood vessel growth that accompanies metastases. The new blood vessels literally provide nutrition and sustenance to new and growing tumors throughout the body. That may be one basis, medical researchers contend, for curcumin’s efficacy. In 1998, Harvard researchers tested the substance for its ability to inhibit the growth of endothelial cells; those which line the interior of blood vessels, as well as the growth of new blood vessels in the corneas of mice.
“Curcumin effectively inhibited endothelial cell proliferation in a dose-dependent manner,” they wrote. “Curcumin and its derivatives [also] demonstrated significant inhibition of …corneal neovascularization in the mouse…These results indicate that curcumin had direct antiangiogenic activity in vitro and in vivo. The activity of curcumin in inhibiting carcinogenesis in diverse organs such as the skin and colon may be mediated in part through angiogenesis inhibition.”13
Other studies, such as one by Taiwanese scientists four years ago, examined the molecular mechanisms behind curcumin. They concluded, after studying curcumin’s effect on mouse fibroblast cells, that it directly suppresses the expression of nuclear oncogenes, the genetic mutation that launches the process of cancer cell growth, among other things.14 Other studies have examined the possibility that the mechanisms behind curcumin may lie in its ability to block the activity of specific oxidants, and halt signal transduction pathways between cells during the initial tumor growth process.15