Curcumin, an active ingredient in turmeric, is an antioxidant. Antioxidants are compounds that can protect the body's cells from damage caused by activated oxygen molecules known as free radicals.
Recently, curcumin has received a great deal more attention in studies than turmeric as a whole herb. Researchers are studying curcumin to learn whether it is an effective anti-inflammatory agent and whether it holds any promise as a cancer drug.
According to a review article published by researchers from the Ohio State University in Columbus, curcumin demonstrated anti-cancer effects at virtually all stages of tumor development in rodents. It showed potential to kill cancer cells and prevent normal cells from becoming cancerous.
A French laboratory study concluded that curcumin appeared to be a potent inhibitor of cancer development. Several more laboratory studies also concluded that curcumin might prevent and slow the growth of some types of tumor cells.
Animal studies in the United Kingdom suggested that curcumin slows the growth of adenomas in the intestine in mice. A recent United States mouse study also showed that it slowed the spread of breast cancer to the lungs.
One concern about curcumin has been about how little reaches the rest of the body when it is taken by mouth. Because curcumin is hard to absorb, some studies in animals have used an injectable form.
One study of 15 patients with colorectal cancer was done to find out how much curcumin they could safely take and whether they could take a dose large enough to be detected in the blood. The patients were able to take 3.6 grams of curcumin without noting ill effects. At this high dose, some curcumin and its products (metabolites) were found in the blood. The researchers recommended that this dose be used when curcumin is tested for effects outside the intestine. Lower doses may work for the stomach and intestine. Even though it does not absorb well into the body, it has been shown to absorb into the colon lining and even into any cancerous tissue in the colon. Other small studies have found people were able to take up to 10 grams per day for a period of a few weeks without noting problems.
Human studies of curcumin in cancer prevention and treatment are in the very early stages. Further study is needed to find out what role, if any, curcumin may play in the prevention or treatment of cancer.
Curcumin is being studied to see if it helps other diseases as well. One small study of curcumin, along with another antioxidant called quercetin, was done in adults who received kidney transplants. Those who received the combination in high dosages had fewer transplant rejections than those who received lower doses or placebo. More studies are needed to find out if this holds true. Curcumin may also promote the emptying of the gallbladder, but again, more human studies are needed.
Early studies showed promise that curcumin could correct the problem of cystic fibrosis, but later studies have been inconsistent and often showed no effect. Curcumin also seemed to help prevent stomach ulcers in rodents, although there aren't good studies in humans to recommend it for this use.
Early research has suggested that curcumin may help lower "bad cholesterol," reduce inflammation, and help with arthritis symptoms, although more reliable human studies are still needed. Tests of curcumin in HIV disease have been mixed and have generally not shown it to be helpful. In studies of mice, curcumin appeared to help with blocking the plaques and proteins that cause problems in the brain during Alzheimer Disease.
Although lab and animal tests look promising, careful study is needed to find out whether curcumin will be useful for treating these conditions. It is important to remember that extracted compounds such as curcumin are not the same as the whole herb, and study results are not likely to show the same effects.