Role of Ginseng in Diabetes and Weight Loss
Ginseng root has been used in Chinese and Korean cultures since ancient times. The plant belongs to the genus Panax, which has been in use in traditional medicine over centuries. The name ginseng comes from the Chinese words “Jen Sheng”, meaning “man-herb”, because of the humanoid shape of the root of the plant, which is the part most commonly consumed (1).
There are varieties of ginseng based upon the origin of plant from Korea, China and America. Traditionally, wild ginseng that grows naturally in mountains was handpicked and was used for medicinal purposes, but today with rising trends of its usage, cultivated varieties have also been introduced. These days, not only the fresh varieties but processed varieties (white and red ginseng) with improved shelf life are also available in the market. It is available as powders as well as extracts. Ginseng is predominantly produced in Canada, South Korea, and the U.S. Some of the top exporters of ginseng are Canada, South Korea, China, Hong Kong, and the United States. China is one of the leading ginseng consumers (2). According to an estimate, in terms of value, the global ginseng market is projected to experience a healthy compound annual growth rate of 4.8% between years 2018 and 2027. This may be due to globalization, increased consumer acceptance for oriental and Asian flavors and demand for Chinese herbal medicine (3).
With rising trends of functional foods, there have been recent advances in studying the health and pharmacological properties of ginseng root. It has been found to have following health benefits
* Antidiabetic properties
* Aids in weight loss
* Protects against cardiovascular problems
* Anti-inflammatory actions
* Protects against cancer
Active components of ginseng
Two basic functional compounds, Ginsenoside and Gintonin, have been identified in ginseng roots. Ginsenosides are steroid glycosides belonging to dammarane family of molecules. Many studies suggest that ginsenosides have antioxidant properties. They have been observed to increase internal antioxidant enzymes and act as a free-radical scavenger. In addition, they have been suggested to haveneuroprotective properties and could be useful against neurodegenerative diseases such as Alzeimer’s and Parkinson’s. These effects have been explained by the fact that these compounds are similar to steroid hormones and may act as partial agonists of steroid hormone receptors. Gintonin is a glycolipoprotein fraction derived from ginseng which is also known to be protective against neurodegenerative diseases and cancer (1, 4).
Antidiabetic properties of ginseng have been studied in several researches. Evidence suggests that ginseng can help in diabetic control by lowering blood glucose levels and increasing insulin sensitivity (6). This antidiabetic property of Ginseng can be attributed to its role in modulating PPAR-γ gene expression. Therapeutic potential of synthetic agonists (activators) of PPAR-γ against diabetes is used in medicine. Through similar pathway, Gensenoside component found in ginseng has been studied to increase the expression of PPAR-γ2, which facilitates the translocation of glucose transporters (GLUT-4 and GLUT-2) and increases the release of enzyme Glucokinase. GLUT-4 and GLUT-2 are carriers of glucose which facilitate the uptake of glucose across cell membranes, with GLUT-4 being insulin dependent and GLUT-2 being insulin independent. Insulin released in response to high blood glucose levels binds to insulin receptors on liver, muscle or adipose cell which activates a series of reactions finally resulting in expression of GLUT-4 on cell surface. GLUT-4 then facilitates the diffusion of glucose from blood into the cell down the concentration gradient. This entering glucose molecule is subjected to the actions of enzyme Glucokinase (in liver cells) or Hexokinase (in muscle cells). These enzymes catalyse the phosphorylation of glucose at 6th carbon position which forms first step of glucose catabolism (glycolysis) as well as formation of glycogen (glycogenesis). Once a glucose molecule is destined for further metabolic reactions, it cannot be returned back into blood, therefore, resulting in lowering of blood glucose levels, unless otherwise needed. Of these two enzymes described (glucokinase and hexokinase), Glucokinase (found in hepatocytes) has been studied to be modulated by ginseng consumption.
In short, the combined effects of increased insulin sensitivity, translocation of GLUT-2 and GLUT-4 and increased production of enzyme glukokinase results in increased uptake of glucose by cells and thus decreases the blood glucose levels.
Research suggests that ginseng can lead to weight loss and thus is regarded to have anti obesity properties. Evidence from animal study conducted in USA indicates that a dose of ginseng extract at 150mg/kg body weight fed for 12 days can significantly reduce body weight (7). In addition, ginseng has been found effective in treating obesity in leptin deficient animal models. In a Korean study, obese leptin deficient mice showed significant reduction in their weight as well as improved insulin sensitivity upon being fed a dose of 100-200mg/kg body weight ginseng extract for 4 weeks (8).
In vitro as well as invivo studies suggest that ginseng and ginsenosidescan increase energy expenditure by stimulating the adenosine monophosphate-activated kinase pathway and can reduce energy intake. Gensinoside has been studied to leptin signaling in hypothalamus. Leptin is a hormone produced by adipocytes which regulates energy homeostasis through its anorexic signals to hypothalamus, giving a feeling of satiety. Leptin deficient individuals can suffer from very stubborn forms of obesity risking them to several metabolic disorders. Several inflammatory markers (p-IκB kinase, interleukin (IL)-6, and IL-1β) resulting from continued feeding of high fat diets can lead to leptin resistance. Ginseng potentially has a role in alleviating obesity because of its ability to decrease the expression levels of inflammatory markers and thus helping leptin to perform its anorexic functions. Through this mechanism, gingeng may keep a check on food and energy intake and thus can prevent obesity (9).
In addition, some forms of ginsenosides can suppress pancreatic lipase activity. Pancreatic lipase is a lipolytic (fat catabolizing) enzyme released by pancreas which aids in final cleavage of lipid moieties. Inhibition of pancreatic lipase activity can lead to excessive excretion of undigested fat into feces, thus making it unavailable for further metabolism. Therefore, through this action, ginsenosides may result in excretion of excess fat and can lead to decreasing the overall available energy from food (9).
Ginseng and Ginsenosides have been shown to increase fat utilization through yet another pathway. They can activate adenosine monophosphate-activated kinase (AMPK) pathway. This enzyme (AMPK) stimulates the oxidation of fatty acids and ketogenesis while inhibiting the synthesis of cholesterol, lipids and triglycerides. AMPK also activates the PPAR-α which stimulates fatty acid oxidation, reducing the amount of fatty acids available for lipogenesis (9).