Ethnic Exuberance: Irrational?

Can a Chinese fruit sweeten sugar metabolism and love the heart and blood vessels? At the annual scientific conference of the American Diabetes Association (ADA), researchers from Hong Kong Polytechnic University and the Chinese University of Hong Kong presented findings from their long-term intervention trial assessing a standardized extract of Dang zhi (Dz). The study reported dramatic effects, comparable to the current generation of diabetes and lipid-lowering thiazolidinedione drugs and statins, although only an inert placebo was used as a control.

Dz is indigenous to many southern Chinese provinces, and has long been used in Chinese cuisine (in soups and teas) and in the traditional Chinese medicinal management of cardiovascular disorders and diabetes. It can be found in several Asian markets across North America. Study participants were screened from patients admitted to Prince of Wales Hospital for chest pain. Those with a confirmed diagnosis of atherosclerotic disease (ultrasound of the carotid arteries) and type 2 diabetes (fasting glucose and hemoglobin A1C) and able and willing to participate in the study were enrolled.

“At six months those randomized to the Dz extract displayed a marked increase in a biomarker with presumed anti-atherosclerotic effects, paraoxonase 1 (PON1),” offered Dr. Chung Tsung, the lead investigator of the study. “What was unexpected was the 28% drop in A1C and the 26% increase in whole body glucose disposal,” he added. All patients were assessed every six months. Of the 122 patients that were enrolled, 109 completed the study as defined by the protocol. “Because the pa­tients were so motivated, only one capsule a day was required, and adverse events were so rare and mild, we had great retention,” said Dr. Helen Chiu, a coinvestigator.

The most striking results manifested in the 18 and 24 month assessments: improvements in PON1, A1C and carbohydrate metabolism were sustained through the close of the study, but at the last two clinical assessments carotid atherosclerosis had regressed by 14% and 21%, respectively. “We were literally stunned with these results and triple confirmed them,” said Dr. Tsung with a still apparently transfixed tone. “We could explain the PON1 data, and even came to accept the A1C findings, but regression of plaque, of this magnitude? I still find it hard to fall asleep at night because my mind is behaving like a hummingbird, thinking of all the follow up studies we could do.”

The Dz extract was developed by Hong Kong-based Materia Medica Ltd. using trade secret bioprocessing techniques applied upon an elite clone of a Dang zhi variety from an undisclosed province. “We did some ‘medical sleuthing’ looking at the pro­vinces that had the lowest incidence of symptomatic heart disease (via medical records) and high consumption of the fruit,” said Tsung Yuan, general manager of Materia Medica. “We [sent] our ethnobotanists and crop scientists out to collect the samples and develop a clone that had the ideal chemoprofile and we started cultivating.” Mr. Yuan was reluctant to divulge what the chemoprofile was, but he did say “We have it tightly dialed in—think of it as Coca-Cola syrup. It’s always the same.”

At the ADA meeting Materia Medica staged a press conference the day of the presentation and disclosed that they had formed a strategic marketing alliance with two large consumer health companies but withheld the names. Both were described as having continental distribution in both pharmacies and independent and chain natural foods stores—one having North A­merican headquarters and the other based in London, U.K. Sales of the Dz extract are expected to commence by January 2006.

The buzz at the press conference spilled onto the meeting floor, fostering lively discussions with scientists that were not involved in the study. Dr. Sandra Leigh, a nutritional biochemist and geneticist at Brigham and Women’s Hospital in Boston, stated “The study by Dr. Tsung and colleagues was well designed, well controlled and yielded some very encouraging results, but they didn’t evaluate a large population. But let’s assume that they had enrolled 10 times as many patients and obtained the same results. This would be a landmark study but limited to first generation Chinese—who had been genetically exposed to it for a multitude of generations. Can we extrapolate findings from one ethnic gene pool to a very different one? We are seeing the emergence of drugs specific to ethnic groups and pharmacogenomics making its way into clinical trials, and here we see a natural product with efficacy and ‘genetic imprinting’ from the diet being offered to a vastly different population, with the unwarranted assumption that the efficacy translates.

“This is not a first. Look at the studies done on populations from India and Scandinavia with different ‘weight loss’ in­gredients. The results they obtain there are positive but studies done in the U.S., with the same ingredients, are either lacking or show no evidence of efficacy. Still, the major venue for marketing these ingredients is the U.S. We could be doing harm or nothing while promising everything. For the U.S. market, companies need to do re­search on Americans. That would be impressive to me.”NW