July 30, 2007
Turmeric, the main ingredient in curry spice, may contain an immune-boosting substance that helps protect the brain against Alzheimer's, researchers report. The findings build on earlier evidence suggesting that curcumin, the natural pigment that gives turmeric, curry, and everyday American mustard its yellow color, may have benefits for the brain. The findings were reported online in the Proceedings of the Natural Academy of Sciences.
In test tube experiments, researchers in Los Angeles and San Diego found that a natural pigment in turmeric boosted the immune system's ability to remove beta-amyloid, a toxic protein that accumulates in the brains of those with Alzheimer's disease. People with Alzheimer's disease cannot efficiently remove beta-amyloid from the brain. As a result, the sticky protein builds up, forming plaques that eventually kill off healthy brain cells.
Scientists speculate that this defect may be related to abnormal regulation of particular genes important for proper brain function and memory. In the study, the researchers exposed immune system cells called macrophages to the active ingredient in curry, a substance with the scientific name "bisdemethoxycurcumin." Exposing the immune cells to this substance bolstered gene function and the ability of macrophages to clear beta-amyloid.
Although it's a long way from the test tube to people, researchers are hopeful that the research may point to new clues about the role of the immune system in Alzheimer's disease. It could also lead to new medicines or measures to minimize the impact of the ailment.
Put Zing in Your Diet
Earlier studies have shown that turmeric and curry spice may break up amyloid plaques in the brains of mice. [See the article, "Alzheimer's Fighter in Your Spice Rack?."] Active compounds in the spice also reduced the ability of beta-amyloid to form sticky clumps in the brain. Other research shows that the spices contain powerful antioxidants and inflammation fighters that may fight cancer, heart disease, and other ills of old age.
Traditional Indian healers have long harnessed the power of curry to treat a range of ailments. The possible benefits of curry are further bolstered by population studies. In countries like India, where curry is served at daily meals, rates of Alzheimer's disease appear to be much lower than they are in the United States. The prevalence of Alzheimer's in one Indian community was four times lower among men and women in their 70s than it is in seniors in the U.S.
It is not known, however, whether people in India are less likely to develop Alzheimer's disease or whether those who do develop it die quickly and are not counted in the population studies. It should also be pointed out that diets rich in curry are not the only difference between Indian populations and populations in the U.S. and other countries. If there really is less Alzheimer's disease in India it could result from things unrelated to curry.
Still, nutrition experts agree that a dash of turmeric in your diet may be a good thing. Turmeric (Curcuma longa) gives Indian curries their distinctive zing. The same spice is what gives the mustard Americans slather on their hot dogs its bright yellow color. In Japan, villagers drink copious quantities of a healthful turmeric tea. While you're not likely to get therapeutic quantities of turmeric in your daily meals, a night out for Indian food or a healthy slathering of mustard on your sandwich may be a wise choice.
Proceedings of the National Academy of Sciences, July 17, 2007, online early edition.