Tea may be ‘sweet’ way to lose weight

Zhijun Liu, Bogren, Richard C.  |  11/11/2008 10:50:09 PM

News Release Distributed 11/11/08

Drinking tea to lose weight may not be a farfetched idea if a group of Louisiana researchers can pinpoint and quantify the functional components of Chinese sweet tea and blackberry leaves.

The compounds of interest are gallic acid and ellagic acid – two polyphenols or antioxidants – in those plants, said Dr. Zhijun Liu with the LSU AgCenter’s School of Renewable Natural Resources. In the body, they apparently function to inhibit angiogenesis – the process by which new blood vessels are formed.

“All adult angiogenic processes are a cause of disease with the exception of a few physiological processes like wound healing, menses and placental-fetal formation,” Liu said. “Tumors cannot grow beyond the size of a pin head without first inducing new blood vessel formation.

“Inhibiting angiogenesis can prevent cancer – and perhaps even fat tissue – from developing beyond the simple limits of existing blood vessels,” he said.

Researchers have been looking at these types of compounds as cancer treatments because tumors can’t grow if they can’t produce blood vessels to feed them. Now, researchers believe the same process for restricting cancers can be exploited to prevent fat cells from growing.

“We’re looking at foods that can influence weight loss,” Liu said.

Liu has been working with a number of plants that produce functional foods – foods with benefits beyond mere nutrition. The latest, Chinese sweet tea and blackberry leaves, appear to contain properties that can help people control their weight.

The researchers have been looking at how these components behave in rats.

Liu has extracted and powdered the compounds from the plant leaves and reformulated them for consistency in dosage. Dr. Roy Martin in the LSU AgCenter’s School of Human Ecology then fed the compounds to laboratory rats.

“So far, we’ve found absorption from oral administration both in the urine and blood serum,” Liu said. “And the test rats showed less weight gain than control rats, even though food intake was about the same.”

Liu has been working with Dr. Eugene Woltering in the Stanley S. Scott Cancer Center in the LSU Health Sciences Center in New Orleans and Dr. Frank Greenway, medical director at the Pennington Biomedical Research Center in Baton Rouge.

“We hope to compare human response with rats’ response to get an absorption profile,” Liu said. “If we do, we can propose a pilot human study.”

Liu said a major challenge in identifying specific benefits from functional foods is the ability to determine accurately how much of a particular food or food component is necessary to get the desired result.

“Could you ask someone to drink a liter of sweet leaf tea every day?” he asked. “Perhaps. But how much is too much? And how do you know how much of a compound is in each liter?”

To answer that type of question, Liu has been developing a method of “fingerprinting” botanical foods to assess batch-to-batch variations so he can provide consistent samples for research or product development.

The fingerprints are in fact liquid chromatographic measurements of the various compounds in a particular sample of plant tissue.

“We develop protocols for reproducing quality botanical products,” Liu said of the work in his laboratory. “If each batch is not the same chemical composition, we can’t complete research.

“We need consistency to be sure investigators are testing the same thing over and over again,” he said. “We need to eliminate doubt due to test sample variations.”

Liu said he and his laboratory personnel exert great effort to develop standardization protocols and produce enough products for clinical trials.

“If you can’t demonstrate consistency, how can you claim a benefit?” he asked.


Contact: Zhijun Liu at (225) 578-4131 or zliu@agcenter.lsu.edu

Writer: Rick Bogren at (225) 578-5839 or rbogren@agcenter.lsu.edu

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