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New Research on Antioxidants Shows Surprising Role for Coffee

Eastman, Peggy

doi: 10.1097/01.COT.0000290968.61298.07
AMERICAN CHEMICAL SOCIETY ANNUAL MEETING
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WASHINGTON, DC—Recent studies from the American Institute for Cancer Research (AICR) and other groups have highlighted the importance of polyphenols, antioxidant compounds in fruits, vegetables, and tea, in reducing the risk of developing cancer. But, while groups such as the National Cancer Institute and the AICR have consistently advised Americans to eat more fruits and vegetables, Americans actually get most of their antioxidants from a surprising source: coffee.

That finding comes from research presented here at the American Chemical Society National Meeting by Joe A. Vinson, PhD, Professor of Chemistry at the University of Scranton (PA).

“I found out to my amazement that coffee was the number one source of antioxidants” in the US diet, he said, noting that both caffeinated and decaffeinated coffee brands seem to provide the same levels of antioxidants.

Dr. Vinson measured in milligrams the top 10 sources of antioxidants consumed on average in the US diet. Coffee was far and away the number one source at 1,299 mg per day. Black tea, the second source, was not even close at 294 mg per day.

Trailing tea in order of the amount of antioxidants generally consumed daily were bananas (76 mg), dry beans (72 mg), corn (48 mg), red wine (44 mg), lager beer (42 mg), apples (39 mg), tomatoes (32 mg), and potatoes (28 mg).

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Dr. Vinson's study was an in vitro test, and he emphasized in an American Chemical Society news briefing that there are limitations to this kind of study, including not knowing how much of the antioxidant compounds are actually being absorbed by the body.

He also was quick to say that coffee-loving Americans should not overdo their coffee consumption in hopes of loading up on antioxidants. One or two cups of coffee a day are plenty, he said.

He also urged more consumption of tea for those who don't like coffee, along with a higher consumption of fruits and vegetables for the general population. Dr. Vinson noted that on the basis of the amount of antioxidants per serving size, dates, cranberries, and red grapes are among the best fruits to eat.

In a world with some 8,000 polyphenols, it is impossible to know just what all of them do, Dr. Vinson said, noting that these compounds are designed to protect plants bombarded by ultraviolet radiation and other insults.

“There are thousands of polyphenols…we'll never know them all. We just don't know all the good things that come from these polyphenols yet. The proof is in vivo.”

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Other Research Highlights

Highlights of other cancer-related research presented at the meeting follow.

  • A novel investigational compound that interferes with the production of gangliosides, molecules in the membranes of most cells, could potentially serve as an alternative to traditional cancer treatments such as chemotherapy and radiation or as a nontoxic addition to these standard treatments, reported Stephan Ladisch, MD, Director of the Center for Cancer and Immunology Research at the Children's Research Institute and Professor of Pediatrics and Biochemistry/Molecular Biology at George Washington University School of Medicine.
  • The synthesis and shedding of gangliosides by tumor cells (which produce gangliosides at a much more rapid rate than normal cells do) have been implicated in immune function, angiogenesis, and fibroblast proliferation. In work with an experimental mouse melanoma model, Dr. Ladisch administered a carbohydrate compound, OGT2378, which blocks the production of an enzyme cancer cells require to make gangliosides.
  • The tumors in OGT2378-treated mice were one-tenth the size of tumors in untreated mice, said Dr. Ladisch, who noted that with this approach—unlike with toxic chemotherapy drugs—the tumor's own cellular mechanics are being manipulated and changed to stop its growth.
  • Benjamin Cravatt, PhD, Professor in the Department of Cell Biology and the Skaggs Institute for Chemical Biology at the Scripps Research Institute, reported on his work with activity-based protein profiling, an emerging proteomics technology that can detect the human proteins associated with breast cancer, including some not identified previously.
  • Dr. Cravatt combined activity-based protein profiling with the proteomics method multidimensional protein identification technology (MudPIT), which relies on mass spectrometry, to analyze protein pools in more detail. Dr. Cravatt said he hopes that using these two methods together could detect protein markers of disease that evade detection by other means.
  • Karen J. Brewer, PhD, Associate Professor of Inorganic Chemistry at Virginia Polytechnic Institute and State University, presented research on the assembly of manmade molecular complexes that can enter cancer cells, and when signaled to do so, can deliver anti-cancer drugs or cause the cancer cells to change.
  • These new manmade “supermolecules” have many units that will absorb light, and are used to deliver photodynamic therapy. To their cancer-fighting supermolecules Dr. Brewer and her team have added platinum, which has anti-cancer activity because it binds to DNA and inhibits cell replication.
  • The therapeutic supermolecule complexes activate only with visible light, so the researchers added a luminescent tag that glows in the presence of ultraviolet light. Dr. Brewer noted that since it is common practice in medicine to use luminescent dyes to study cells, pathology laboratories have the equipment needed to monitor cancer drug delivery via the supermolecules.
  • Researchers from Meiji Pharmaceutical University in Japan reported on their work testing some 50 Japanese mushrooms to find an inhibitor of tyrosine kinase, which plays a key role in intracellular signaling and cancer proliferation. The team has discovered that a methanol extract from the fruiting body of Polyozellus multiplex, the blue chanterelle mushroom, inhibited the activity of tyrosine kinase via the molecule polyozellin.
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  • In a separate study on mushrooms, Joy Dubost, a doctoral candidate in food science at Pennsylvania State University, found that cultivated mushrooms sold in US grocery stores are a good natural source of the antioxidant ergothioneine. She found that white button mushrooms, the kind most commonly eaten in the United States, have 12 times more of the antioxidant than wheat germ and four times more than chicken liver—previously the top-rated sources of ergothioneine.
  • In other research from Penn State, Michael Pishko, PhD, Professor of Chemical Engineering and Materials Science and Engineering, and his colleagues reported on research that encases a chemotherapy drug in a polymer nanoshell so it will circulate longer in vascularized areas such as cancerous tumors. The scientists first make nano-sized powders of the drug they wish to deliver—in this case paclitaxel—and encase it in the polymeric nanoshell.
  • The polymer shell allows the drug to travel through the bloodstream like a “stealth missile” (with less toxicity to normal tissues) to its intended cancerous target. The nanoshell has a tentacle-like projection that targets a receptor on a tumor cell; once the encapsulated drug hits its target, it attaches to the target and releases its cancer-fighting contents.
  • Dr. Pishko said he hopes this drug delivery method might eventually have application to gene therapy as well as cancer treatment. It is not feasible for brain cancers because of the blood-brain barrier.
  • At a symposium on tobacco carcinogenesis, Trevor M. Penning, PhD, Professor of Pharmacology and principal investigator of a program project on carcinogenesis at the University of Pennsylvania (and a co-organizer of the symposium) reported on the means by which polycyclic aromatic hydrocarbons from smoking tobacco may form lesions in DNA, which can trigger gene mutations that allow cancer cells to emerge and grow without being controlled.
  • Mimi C. Yu, PhD, Professor of Research in the Department of Preventive Medicine at the University of Southern California Keck School of Medicine in Los Angeles, reported on 4-aminobiphenyl (4-ABP), a compound present in tobacco smoke, a known human bladder carcinogen. She presented data showing that being female produces a higher risk of bladder cancer in tobacco smokers.
  • Symposium co-organizer Stephen S. Hecht, PhD, Head of Cancer Prevention at the University of Minnesota Cancer Center, said that understanding the mechanisms by which tobacco products cause cancer can help shed new light on controlling tobacco use, predicting individual susceptibility to cancer from use of tobacco, and preventing cancer in general.
© 2005 Lippincott Williams & Wilkins, Inc.
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