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Key Points
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The spices did not affect normal stem cells.
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The tissue concentrations tested are hard to obtain from spiced foods alone.
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Supplements might deliver significant levels; clinical tests are needed.
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Rogue stem cells seen as cancer risk and selective target of spices
The new findings relate to the effects of spice compounds on stem cells, which are essential to life and offer therapeutic potential … but can go bad.
Normally, stem cells develop into the various kinds of cells the body needs: a process called “differentiation”.
But some stem cells never differentiate into various body cells … and these abnormal stem cells are believed to form tumors over time.
Two human genes called BRCA1 and BRCA2 belong to a class of genes known as tumor suppressors.
Certain mutations in these genes make them ineffective tumor-deterrents, and so they are linked to hereditary breast and ovarian cancer.
A woman's risk of developing breast or ovarian cancer is much higher if she inherits a harmful BRCA1 or BRCA2 mutation (NCI 2009).
And recent findings show that breast tissue from women who carry the BRCA1 mutation contains islands of stem cells that express a genetic marker called ALDH1, which is associated with the inability of a stem cell to differentiate (Kakarala M et al. 2009).
The big news from Michigan is that compounds from both turmeric and pepper stopped the growth of abnormal, non-differentiated stem cells … at least in the test tube.
As Dr. Kakarala said, “If we can limit the number of [abnormal] stem cells, we can limit the number of cells with potential to form tumors.” (UMHS 2009)
Critically, normal stem cells were unaffected by the compounds, which affected only the cancer stem cells.
Study details how the spices stop rogue stem cells
The University of Michigan team exposed stem cells from human breast tissue to the spice compounds (Kakarala M et al. 2009).
The results showed that curcumin – a powerful antioxidant and yellow pigment from turmeric – and piperine from black pepper each decreased the number of abnormal stem cells while having no effect on normal, “differentiated” cells.
Fortunately, the results also detailed how the spice extracts halted growth of the rogue stem cells.
First, they targeted stem cells carrying the risky ALDH1 genetic marker associated with a failure to differentiate into useful body cells.
Second, they blocked a dangerous “cell signaling” pathway called Wnt, which allows stem cells to “self-renew” … that is, the Wnt signal lets stem cells keep dividing without ever differentiating into the cell types needed by the body.
Supplements might deliver sufficient oral doses
The researchers used doses equivalent to 20 times the amount most Westerners would consume from using the whole spices in meals.
But getting comparable amounts from food might not be so unusual in India or Pakistan, where both spices are consumed daily and copiously.
In contrast, some curcumin and piperine supplements contain very high concentrations of these compounds.
It will take clinical research involving breast biopsies to discover whether high intakes of curcumin and piperine – whether from whole spices in foods, or from supplements – would end up in women’s breast tissues in the concentrations found effective in the new study.
On the other hand, Dr. Kakarala’s group observed half the stem-cell-stopping benefit at half the concentration of spice extracts.
Thus, the extent of the spice extracts' beneficial effects are "dose-dependent", and lower levels may provide significant preventive benefit.
Because this is research on breast cells and not a clinical trial, it would be premature to expect a certain preventive effect from curcumin or piperine supplements.
But in light of the many promising studies on these and their typical curry-mix companions – clove, coriander (cilantro seed), and cardamom– are also becoming increasingly appealing from a wellness standpoint.
This is particularly true with regard to preliminary work on curcumin’s possible preventive effects in Alzheimer’s, arthritis, and cancer.
Add some bright orange-yellow color and some preventive potential to your next pot of rice, veggies, or beans!
When choosing a curcumin supplement, look for one that is standardized to contain 90 percent or more curcuminoids, because – compared with the single chemical called curcumin – this group of closely related antioxidant compounds has proven more effective in a variety of experimental contexts.
The study was supported by the National Institutes of Health, and a supplement raw material supplier (Sabinsa) donated the curcumin and piperine used in the study.
Sources
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Ginestier C, Hur MH, Charafe-Jauffret E, Monville F, Dutcher J, Brown M, Jacquemier J, Viens P, Kleer CG, Liu S, Schott A, Hayes D, Birnbaum D, Wicha MS, Dontu G (2007) ALDH1 is a marker of normal and malignant human mammary stem cells and a predictor of poor clinical outcome. Cell Stem Cell 1:555–567
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Kakarala M, Brenner DE, Korkaya H, Cheng C, Tazi K, Ginestier C, Liu S, Dontu G, Wicha MS. Targeting breast stem cells with the cancer preventive compounds curcumin and piperine. Breast Cancer Res Treat. 2009 Nov 7. [Epub ahead of print]
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Liu S, Ginestier C, Charafe-Jauffret E, Foco H, Kleer CG, Merajver SD, Dontu G, Wicha MS (2008) BRCA1 regulates human mammary stem/progenitor cell fate. Proc Natl Acad Sci USA 105:1680–1685
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National Cancer Institute (NCI). BRCA1 and BRCA2: Cancer Risk and Genetic Testing. Reviewed 05/29/2009. Accessed at http://www.cancer.gov/cancertopics/factsheet/Risk/BRCA
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University of Michigan Health System (UMHS). Spices halt growth of breast stem cells, U-M study finds. December 08, 2009. Accessed at http://www2.med.umich.edu/prmc/media/newsroom/details.cfm?ID=1401
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