DIETARY ANTICANCER AGENTS

Most modern drug-targeted therapies for cancer treatment, besides being enormously expensive, are associated with serious side effects and morbidity. In a recent search Shanmugam et al (2011) present evidence on numerous dietary agents identified from fruits and vegetables that act on multiple signal transduction and apoptotic cascades in various tumor cells and animal models. Some of the most interesting and well documented are turmeric (curcumin), resveratrol, silymarin, EGCG, and genistein.

1. Curcumin is the principal curcuminoid of the popular Indian spice turmeric, which is a member of the ginger family. Curcumin is what gives the Curry its characteristic bright yellow color and strong taste.

Curcumin potential anticancer effects stem from its ability to induce apoptosis (programmed cell death ) in cancer cells without cytotoxic effects on healthy cells. Co-supplementation with 20 mg of piperine (extracted from black pepper) significantly increased the absorption of curcumin. However, the increase in absorption only occurred during the first hour. Due to its effects on drug metabolism, piperine should be taken cautiously by individuals taking other medications. Some benefits of curcumin, such as the potential protection from colon cancer, may not require systemic absorption. In any way potential risks and side effects in high doses (>2–12 grams) have not been well documented especially for pregnant women.

2. Resveratol is a stilbenoid, a type of polyphenol, and a produced naturally by several plants when under attack by pathogens such as bacteria and fungi. In mouse and rat experiments, anti-cancer, blood-sugar-lowering and other beneficial cardiovascular effects of resveratrol have been reported. These results have yet to be replicated in humans. In small amounts, resveratrol can be found naturally in grapes, some green teas, and even peanuts. It is also the main ingredient that gives red wine natural anti-aging properties.

In addition resveratrol treatment appeared to prevent the development of mammary tumors in animal models; however, it had no effect on the growth of existing tumors. Injected in high doses into mice, resveratrol slowed the growth of neuroblastomas.

Long term effects of using resveratrol in a capsule are as of yet unknown.

3. Silymarin The most biologically active ingredient found in silymarin is silibinin which is extracted from milk thistle (Silybum marianum). Both in vitro and animal research suggest that silibinin has hepatoprotective properties that protect liver cells against toxins and affects to blood-sugar lowering. Silibinin has also demonstrated anti-cancer effects against human prostate adenocarcinoma cells, estrogen-dependent and -independent human breast carcinoma cells, human ectocervical carcinoma cells, human colon cancer cells, and both small and nonsmall human lung carcinoma cells.

3. Genistein is one of several known isoflavones that its found in high doses in soy. Genistein and other isoflavones have been found to have antiangiogenic effects (blocking formation of new blood vessels), and may block the uncontrolled cell growth associated with cancer. It is resempling to estroegen Genistein binds itself in place of estrogen on receptors in cancerous cells that need this hormone to grow. Tofu, soy milk, soy flour, miso, and roasted soybeans are all good sources of isoflavones. The average daily intake of isoflavones in Japan is about 200 milligrams. There are lots of theories to explain the anti-cancer action of genistein: inhibition of angiogenesis, inhibition of tyrosine kinases, antioxidant property, and anti-estrogen

There have been no toxic side effects associated with genistein, but because it is a phytoestrogen, there has been some concern that it could actually stimulate the growth of estrogen-stimulated cancers or interfere with the action of birth control pills. Men and women that have been diagnosed with estrogen-related cancers should not consume isoflavones, as there is some research that suggests that genistein and daidzein may aggravate these conditions. Epidemiological studies show that consumption of isoflavones may protect against breast and prostate cancer. There are lots of theories to explain the anti-cancer action of genistein: inhibition of angiogenesis, inhibition of tyrosine kinases, antioxidant property, and anti-estrogen action (it is known that estrogen increases risk for certain cancers).

4. Epigallocatechin gallate (EGCG) is a type of catechin the most abundant catechin in most notably tea, among other plants but not in black tea, as EGCG is converted into thearubigins in black teas. In a high temperature environment, there is a conversion from EGCG to no effective GCG . Thus it is considered inappropriate to infuse green tea or its extracts with overheated water.

EGCG has been shown to bind and inhibit  anti-apoptotic protein which has been implicated in both cancer cell and normal cell survival. High intake of polyphenolic compounds during pregnancy is suspected to increase risk of neonatal leukemia. Bioflavonod supplements should not be used by pregnant women. Consumption of green tea was found to be associated with a reduced risk of lung cancer among non-smokers but not among smokers. (Epidemiology 2001 Nov; 12(6):695-700).

Source

Shanmugam MK, Kannaiyan R, Sethi G. Targeting Cell Signaling and Apoptotic Pathways by Dietary Agents: Their Role in the Prevention and Treatment of Cancer. Nutr Cancer. 2011 Feb 2:1.

Read also:

Gou M, Men K, Shi H, Xiang M, Zhang J, Song J, Long J, Wan Y, Luo F, Zhao X, Qian Z.

Curcumin-loaded biodegradable polymeric micelles for colon cancer therapy in vitro and in vivo.

Nanoscale. 2011 Jan 31. (State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, 610041, )

Masuda M, Wakasaki T, Toh S, Shimizu M, Adachi S.Chemoprevention of Head and Neck Cancer by Green Tea Extract: EGCG-The Role of EGFR Signaling and "Lipid Raft". J Oncol. 2011;2011:540148. Epub 2011 Jan 2.

Singh RP, Tyagi A, Sharma G, Mohan S, Agarwal R. Oral silibinin inhibits in vivo human bladder tumor xenograft growth involving down-regulation of survivin. Clin Cancer Res. 2008 Jan 1;14(1):300-8.