The Spices of Cancer Prevention
For centuries, cultures have used spices to improve health and ward off disease. A growing body of research – primarily lab studies – is now zeroing in on the role specific spices may play in reducing cancer risk.
“There is more and more documentation that several compounds in spices have anti-cancer properties,” says John Milner, PhD, Director of the Human Nutrition Research Center at the US Department of Agriculture and co-author of a review of spices for cancer prevention. There are several potential mechanisms in which spices may work to reduce cancer risk, says Milner, “from changing carcinogen metabolism to modifying the microbiome to cell signaling – all changes that would inhibit the growth of a tumor.”
There are dozens of spices that have pointed to cancer protection in lab studies, with much of the research in its early phases. Some of the spices relatively well studied in cancer prevention include turmeric and garlic. Research is emerging in other spices and cancer risk, such as black pepper, allspice and cinnamon.
Turmeric stands as one of the most extensively studied spices, with over 1,700 lab studies published over the last few decades. It has been used for centuries to treat numerous inflammation-related disorders, including skin conditions, pain and gastrointestinal problems. There are now clinical trials examining its role in reducing cancer risk.
Turmeric gets its yellow pigment from curcumin, a polyphenol that is the primary phytochemical scientists are investigating for its anticancer potential. In the lab, curcumin modulates cell signaling pathways, suppresses tumor cell proliferation and induces apoptosis of cancer cells. There is evidence that curcumin can suppress inflammation and inhibit tumor survival, initiation, promotion, invasion and metastasis. The findings from lab studies have led to clinical trials in humans, which are generally small but have generated promising findings.
One possible way to increase the bioavailability of curcumin may take adding another spice to the diet: black pepper. Research from the University of Michigan has found that the combination of curcumin and piperine improves curcumin bioavailability and inhibits breast stem cell self-renewal.
Piperine, when tested independently, exhibits anti-inflammatory, antioxidant and anticancer activities in cell studies. In addition, studies have found that piperine in combination with the green tea polyphenol epigallocatechin-3-gallate (EGCG) increased the bioavailability of EGCG. “What we found was that when we gave mice EGCG together with piperine, we could increase the amount of the compound [EGCG] that got into the blood and into some of the tissues compared to just giving them EGCG alone,” said Joshua Lambert, PhD, Associate Professor of Food Science at Penn State University and the lead researcher on the animal study.
“We have a study going on right now that AICR funded where we are studying human subjects looking at the same bioavailability markers and we are seeing improved bioavailability in people,” Lambert adds. The piperine dose used was 230 mg, which is about one-eighth of a teaspoon of black pepper.
Although technically a vegetable, garlic is considered a spice because it is typically used for flavoring. Garlic is abundant in phytochemicals: it contains flavonoids, but is especially under study for its sulphur-containing compounds. When raw garlic is crushed or chopped, an enzyme breaks down the compound alliin to allicin, which is then converted to a variety of allyl sulfide compounds that have biologic activity in the body. AICR’s report and its continuous updates concluded that garlic protects against stomach and colorectal cancer.
The potential protective effects of garlic may come from its antimicrobial properties, ability to block the formation of and activation of cancer-causing compounds, improve DNA repair, reduce cell proliferation and promote cell death.
How and How Much
The potential for spices to affect cancer risk is an appealing area of study for scientists because spices are non-caloric and eaten in combination with other foods. They are also easily incorporated into many dishes, adding flavor and variety. Yet similar to fruits and vegetables, spices all have different antioxidant potentials, and it’s possible that some spices may have a greater impact on one type of cancer than another or be beneficial across all cancers. Scientists also need to better understand how much of each spice is needed for cancer protection. Laboratory studies showing health benefits from spices and other flavor enhancers generally involve larger amounts than people use in cooking, usually supplement doses.
But, note experts, if these compounds show the synergy with one another as some lab studies suggest, the high amounts in lab studies may not be needed when a variety of spices are consumed as part of a healthful plant-based diet that provides thousands of phytochemicals each day.
“The question is always how and how much is needed to do that. We need more research on individual spices and their biological consequences,” says Milner. “This is a really exciting area that we need to know more about.”
Excerpted from ScienceNow.
Published on August 22, 2013