Writing in a review in the Journal of Nutritional Biochemistry, scientists from Tennessee State University said a number of investigations had been conducted on ginseng in preventing and treating of obesity.
However, the effect and the relevant mechanisms behind how ginseng works as an anti-obesity treatment are still controversial, they added, and the issue is clouded by the differing uses of American and Asian ginseng in TCM.
The former is used to treat yin manifestations of Qi (life energy), while the latter tackle yang manifestations.
Therefore, Asian ginseng has often been used to help treat, fatigue, poor appetite, diarrhoea, breath shortness, feeble pulse, spontaneous perspiration, febrile diseases, amnesia, insomnia and impotence.
On the other hand, American ginseng is used to treat diseases such as cough, blood sputum, dysphoria, fatigue and thirst.
“Although the potential anti-obesity effect of Asian ginseng has been investigated in mice and humans in Asia in the last several decades, the anti-obesity effect and mechanism of ginseng are still not fully understood, especially in humans,” wrote the researchers.
“Moreover, high-quality studies of the effects of ginseng in the United States are rare, particularly whether and how American ginseng prevents obesity is almost blank.”
They said this was area ripe for further investigation, and pointed to their own unpublished data which showed that while Asian ginseng significantly inhibited fat accumulation in 3T3-L1 cells, American ginseng has no such effect at the same concentration (1 mg/ml).
They suggest this could be due increased fat accumulation caused by one of the major ginsenosides in American ginseng that is not detectable in Asian ginseng
“The different anti-obesity effect between American ginseng and Asian ginseng may also result from the different profiles of other ginsenosides,” they added.
The researchers also said high-quality clinical trials of anti-obesity effect of ginseng and ginsenosides were very limited.
“There is only one study showing that Asian ginseng extract intake exerted a weight loss effect in obese women,” they wrote.
“American ginseng extract or whole plant/berry has not been investigated for anti-obesity in humans. In addition, there is no report using human primary cells investigating the antiobesity effect of ginseng and ginsenosides.”
They argue that standardised ginseng production is sorely needed to overcome the fact that the results of existing studies “are controversial”.
“These controversial results at least partly come from the variety of the quality of ginseng, especially the whole extract and juice. The quantity and composition of ginsenosides in ginseng plants are dramatically influenced by species, age, and part of the plant, cultivation methods, harvesting season, preservation methods and geographical distribution,” they state.
“However, almost all ginsenosides or extracts in these studies were prepared in the individual labs or from different companies, it is almost impossible to keep the quality at the same level, particularly the whole extract.”
The authors concluded; “Although Asian and American ginsengs have similar profiles of active ingredients, the different percentage of crude saponins (4.8%–5.2% in Asian ginseng vs. 7.0%–7.3% in American ginseng) and the specific ginsenoside (Rf only in Asian ginseng, F11 only in American ginseng) may contribute to the different functions of these two ginsengs.”
“Therefore, it is very important to compare the medical effects using modern scientific approaches.”
“Ginseng and obesity: observations and understanding in cultured cells, animals and humans”
- Authors: Hongwei Si, et al.