Curcumin is a fat-soluble chemical compound found in turmeric, a popular Indian spice derived from a plant in the ginger family. Besides its use as a flavoring and coloring agent, turmeric has been used for thousands of years in traditional Chinese medicine and Ayurveda -- a healing practice originating in India, which is now practiced as alternative or complementary medicine. Research over the last 30 years has demonstrated a potential for application of curcumin in disease prevention and treatment. Clinical studies are evaluating the therapeutic potential of curcumin in treatment of cancer, especially colorectal and pancreatic cancers, rheumatoid arthritis, Alzheimer's disease and cystic fibrosis.
Biological Activities of Curcumin
Curcumin has numerous biological effects, including anti-oxidant and anti-inflammatory effects. Most of these effects have been characterized in lab-grown cells and animal models of human disease. These studies show that curcumin can arrest the growth of cancer cells, reduce metastases -- or spreading of cancer cells -- and slow the growth of new blood vessels in tumors. Curcumin also suppresses the activation of molecular targets involved in promoting inflammatory responses. For instance, curcumin inhibits inflammatory cytokines. Cytokines are small proteins released by activated immune cells that help amplify inflammation in immune response. Curcumin improves cellular adaptation to stress, by increasing the synthesis of GCL -- a protein catalyst involved in the production of the intra-cellular anti-oxidant glutathione. Although curcumin has both direct and indirect anti-oxidant properties, this function in human beings is likely indirect. One major concern with the use of curcumin is its limited bioavailability -- fraction of the orally administered curcumin that reaches systemic circulation and is absorbed by target sites -- except in the gastrointestinal tract. A study published in "Cancer Epidemiology, Biomarkers and Prevention" in 2005 showed that oral curcumin supplementation -- at a dose of 3.6 g per day for seven days -- decreased the number of an oxidative DNA adduct -- formed by the combination of peroxidation of a lipid and a nucleotide within DNA -- in malignant colorectal tissue. Scientists are attempting to overcome the poor bioavailability of curcumin by developing new formulations of curcumin. Novel curcumin formulations include complexes of curcumin and phospholipids and synthetic bioactive curcumin analogs -- compounds that resemble drugs structurally but may differ in biological and chemical properties.
Sources
The spice turmeric is made from ground rhizomes -- horizontal underground stems that give rise to shoots and roots -- of Curcuma longa, a perennial zingiberaceous -- ginger family -- plant cultivated in India and other south Asian countries. Curcumin-like compounds constitute about 2 to 9 percent of turmeric, with curcumin being the most abundant amongst them. Curry powder, a mixture of spices commonly used in south Asian recipes, also contains turmeric, although the curcumin content of curry powder varies widely. Curcumin extracts and turmeric essential oils are also available over the counter as dietary supplements.
Dosage and Toxicity
Data from studies examining the dosage, pharmacokinetics and bioavailability of curcumin, mostly from cancer patients, are inconclusive. Results of a study published in 2005 in the journal "Cancer Epidemiology, Biomarkers and Prevention" showed that pharmacologically efficacious levels of curcumin could be achieved with a dosage of 3.6 g of curcumin per day, but not with lower doses. The dosages of curcumin and curcumin-containing turmeric for therapeutic or chemopreventative uses has not been established. Although turmeric is generally regarded as safe by the U.S. Food and Drug Administration, curcumin can slow blood-clotting and may worsen gallbladder problems. Consult with your doctor to determine the suitability and dosage of curcumin or turmeric specific to your health.
Therapeutic Uses
The results from early preclinical and clinical studies show promising results for the use of curcumin in disease treatment. The U.S. National Institute of Health currently has 25 clinical trials listed that are investigating the effects of turmeric, curcumin or curcumin-like compounds in various disorders, ranging from radiation therapy-induced severe skin reactions in breast cancer patients to Alzheimer's disease. A small study in 25 pancreatic cancer patients, reported by researchers at the MD Anderson Cancer Center in 2008, showed that 8 g of curcumin ingested orally for two months arrested tumor growth or tumor regression in a few patients. The researchers propose to examine the effect of curcumin in combination therapies with other drugs and in novel formulations in their future studies. Another study, initiated in 2005 by researchers at the University of California in Los Angeles, is examining the safety and effects of curcumin (administered as a formulation with curcumin and curcumin-like compounds called curcumin C3 complex) in patients with mild-to-moderate Alzheimer's disease. Preliminary results show that the dose and combination used is safe. Curcumin -- 500 milligrams taken four times daily -- provided partial or full symptom relief from dyspepsia -- stomach upset or indigestion, often due to an unidentifiable medical reason, after seven days. In another example, curcumin, when administered along with standard therapy, was effective in maintaining remission in patients with quiescent ulcerative colitis -- an inflammatory bowel disease characterized by periods of dormancy and flare-ups. This data was published in the Journal "Clinical Gastroenterology and Hepatology" in 2006 by Hamamato University School of Medicine Reserachers in Hamamato, Japan. Many of the registered clinical studies are in early stages or are still recruiting patients, and additional results are anticipated to provide a more complete understanding of the efficacy of curcumin and curcumin-like compounds in disease prevention and treatment.
References
- "Alternative Medicine Review"; Anti-inflammatory Properties of Curcumin; Julie S. Mirenka; September 2009
- Linus Pauling Institute, Oregon State University; Curcumin
- "Cancer Epidemiology, Biomarkers and Prevention"; Assessment of Curcumin Levels in the Colorectum and their Pharmacodynamic Consequences; Giuseppe Garcea, et al.; January 2005
- U.S. National Institutes of Health: Registry of Clinical Trials
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