Promising Diet Pill—Not!

A Chinese weight-loss concoction, known simply as NT, has shown promising results in animal tests. Not only have growing rodents gained less weight, but adults actually slimmed some. Subsequent U.S. tests of the herbal combo confirmed those findings—again in rodents. However, when U.S. obesity researchers gave NT to overweight people in a pilot test, a major side effect emerged: diarrhea.

In hopes of overcoming that problem--which traced to natural laxatives in the herbal preparation--the latter research team reformulated the diet preparation. Then, they fed it to 105 healthy people, 18 to 65 years old, for what was to be 24 weeks. One-third got a low-dose mix, another third got double that dose, and a final third got inactive, look-alike pills, termed a placebo. Good news, at the end of 8 weeks: No diarrhea in either treatment group. Bad news: No weight loss, either.

“In fact, the high dose gave less weight loss than the placebo,” Andrew T. Roberts of the Pennington Biomedical Research Center in Baton Rouge, La., and his colleagues report in the March Journal of Medicinal Food. So disappointing were the results that the scientists terminated their study immediately, 16 weeks early.

NT consists of ~40% rhubarb root-and-stem extract, ~26 percent tumeric (Curcuma longae), ~13% red-sage root (Salvia miltiorrhizae), ~13 percent astragulus root, and ~7% dried ginger (Zingiberis officinalis). When the Roberts’ group realized that these natural products also contained gallic acid, a food constituent that has its own weight-loss properties, they decided to make this the primary ingredient in their newly reformulated test preparation. For their test combo, NT became only 20 percent of the total, by weight, with gallic acid making up the remainder.

The team attributes the likely downfall of the new preparation to its reliance on gallic acid. The researchers found that no matter what they did in attempting to augment its absorption, the compound's concentration in blood never exceeded 20 percent of the administered dose—and a max of 10 micromolar concentrations.

Roberts’ team concludes: “GA will not be an effective oral supplement for the treatment of human obesity.”