What is Ginseng
There are 11 known species of ginseng which belong to the genus Panax and the family Araliaceae. The name “ginseng” is used to refer to both American ginseng (Panax quinquefolius) and Asian or Korean ginseng (Panax ginseng). The American ginseng plant can only be used after it has grown for about six years. It has leaves that grow in a circular shape about the stem and flowers that grow in the centre of the plant; have yellow-green colour and are shaped like an umbrella.
The Asian ginseng is a perennial plant with fleshy roots that grows most predominantly in colder climate zones in China and South Korea, and develops concentrated amounts of unique health promoting compounds the longer it grows.
The different varieties of ginseng come with their own set of distinct health enhancing features and specific amounts of active constituents. Ginseng contains various pharmacological components, including a series of tetracyclic triterpenoid saponins (ginsenosides), polyacetylenes, polyphenolic compounds and acidic polysaccharides. The ginsenosides are the most pharmacologically active compounds in ginseng; and their quality and composition in the ginseng plants can be influenced by a range of factors such as the species, age, and part of the plant, cultivation method, harvesting season and preservation method (Lim et al., 2005).
Pharmacology of Ginsenosides
The major ginsenosides are Rg1, Rh1, Rg3, Rb1, Re and Rc. These ginsenosides have bulky molecular structures, and are poorly membrane permeable and prone to degradation. Ginsenosides are known to reveal multiple bioactivities, including neuroprotection, anti-oxidation, angiogenesis modulation and cytotoxicity (Rudakewich et al., 2001; Sengupta et al., 2011; Lei et al., 2007). However, they require biotransformation before they become active, which means; in the human body ginsenoside metabolites have greater biological effects than ginsenosides.
In regards to their pharmacokinetics and bioavailability, ginsenosides are transported across the intestinal mucosa through energy-dependent and non-saturable pathway such as the sodium-dependent glucose co-transporter 1, which belongs to the protein family of glucose transporters. Ginsenosides are known to have poor bioavailability. Han et al. (2006) detected only 3.29% Rg1 and 0.64% Rb1 in rat serum after oral administration of ginsenosides (Han & Fang, 2006; Han et al., 2006). Recent experiments have identified increased bioavailability of ginsenosides when administered with adrenaline, emulsified into lipid-based formulation and after suppression of the p-glycoprotein efflux system which is a family of membrane proteins that transport drugs out of the cell (Leung & Wong, 2010).
Ginsenosides modulate expressions and functions of receptors such as receptor tyrosine kinases (RTK), serotonin receptors (5-HT), NMDA receptors, and nicotinic acetylcholine receptors (AChR). However, direct interactions of ginsenosides with the receptor ligand-binding sites have only been demonstrated in steroid hormone receptors. Moreover, ginsenosides are agonists to steroidal receptors and each ginsenoside is able to bind to multiple steroid hormone receptors (Leung & Wong, 2010). Ginsenosides Rg1 and Re act as ligands of the glucocorticoid receptor while ginsenosides Rh1 and Rb1 are functional ligands of the oestrogen receptors (Leung & Wong, 2010). This could explain the risk factor of potentially aggravating menopausal symptoms after consumption of ginsenosides, and changes in the functioning of the endocrine system after chronic consumption of ginseng.
Reduces Stress, Improves Mood and Brain Function
Ginseng has significant anti-stress properties. The explanation for this could be that Rg1 and Re ginsenosides might act as partial agonists of the glucocorticoid receptor. Moreover, they might compensate insufficient steroidal activities when the intrinsic ligand is absent or inadequate in the system. On the other hand, they also might reversibly occupy certain percentage of the steroidal receptor at low affinity to counter the steroidal effects when they co-exist in a presence of a large amount of intrinsic ligand (Leung & Wong, 2010). Ginseng has also been demonstrated to improve mood and brain function. A randomised control study done by Reay et al. (2010), involving 30 volunteers who were given three rounds of treatments of ginseng and placebo, found that 200 milligrams of ginseng for eight days can slow the fall in mood; and 400 milligram dose of the same can improve calmness and mental arithmetic. Another study done by Lee et al. (2008) suggested the ability of Panax ginseng to enhance cognitive performance in Alzheimer’s disease. This study demonstrated cognitive improvement in the group treated with ginseng, which continued up to 12 weeks.
Has Anti-inflammatory Properties
There is evidence that ginseng has potent effect on key players in the inflammatory cascade. Ginsenosides have shown inhibition of p38 MAP kinase pathway, NF-κB and induced COX-2 in vitro, and inhibition of pro-inflammatory cytokines in vivo (Ahn et al., 2006; Keum et al., 2003). A study done in Korea measured the beneficial effects of Korean red ginseng on children after chemotherapy or stem cell transplantation for advanced cancer. (Lee et al., 2012). The study included 19 patients who received 60 milligrams of Korean red ginseng daily for one year. Blood samples were collected every six months, and as a result of the treatment, the pro-inflammatory cytokines responsible for sending pro-inflammatory signals to the brain which activate inflammation decreased rapidly, with a significant difference from the control group.
Boosts Immune Function and Benefits the Lungs
Ginseng has ability to boost the immune function, helping the body fight off infection and disease. Recent research has emphasised the ability of American ginseng to regulate each type of immune cell, including macrophages, natural killer cells, dendritic cells, T cells and B cells. Ginseng is also known to produce antimicrobial compounds that work as a defence mechanism against bacterial and viral infections. In particular, ginseng has been demonstrated successful in the treatment against lung bacteria, and studies involving rats have shown that ginseng can stop the growth of cystic fibrosis, a common lung infection (Song et al., 1997). Reports show that ginseng also has inhibitory effect on the growth of many viruses, including influenza, HIV and rotavirus. It also has ability to treat a lung disease called chronic obstructive pulmonary disease (COPD), which is characterized as chronically poor airflow that typically worsens over time.
Lowers Blood Sugar Levels
Ginseng possesses glucoregulatory properties and is also known as natural remedy for diabetes. One of the primary difficulties with type 2 diabetes is that the body is not responsive enough to insulin. A study done by Gao et al. (2013) found that Korean red ginseng improved insulin sensitivity, further explaining ginseng’s ability to help lower blood sugar levels and help those struggling with type 2 diabetes.
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- Ahn, J.Y., Choi, I.S. et al. (2006). The immunomodulatory ginseng induces resistance to experimental sepsis by inhibiting Toll-like receptor-mediated inflammatory signals. European Journal of Immunology. 6(36), 37–45.
- Gao, Y., Yang, M. et al. (2013). Ginsenoside Re reduces insulin resistance through activation of PPAR-γ pathway and inhibition of TNF-α production. Journal of Ethnopharmacology. 147(2), 509-516.
- Han, M., Fang, X.L. (2006). Difference in oral absorption of ginsenoside Rg1 between in vitro and in vivo models. Acta Pharmacol Sin. 6(27), 499–505.
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- Keum,Y.S., Han, S.S. et al. (2003). Inhibitory effects of the ginsenoside Rg3 on ester-induced cyclooxygenase-2 expression, NF-kappa B activation and tumour promotion. Mutation Research. 3(15), 523–524.
- Lee, J.M., Jeong, O.H. et al. (2012). The Effect of Red Ginseng Extract on Inflammatory Cytokines after Chemotherapy in Children. J Ginseng Research. 36(4), 383–390.
- Lee, S.T., Chu, K. et al. (2008). Panax ginseng enhances cognitive performance in Alzheimer disease. Alzheimer Dis Assoc Disord. 22(3), 222-226.
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- Lim, W., Mudge, KW. et al. (2005). Effects of population, age, and cultivation methods on ginsenoside content of wild American ginseng (Panax quinquefolium). Journal of Agricultural Food Chemistry. 5(53), 8498–8505.
- Reay, J.L., Scholey, A.B. et al. (2010). Panax ginseng (G115) improves aspects of working memory performance and subjective ratings of calmness in healthy young adults. Human Psychopharmacology. 25(6), 462-471.
- Rudakewich, M., Ba, F. et al. (2001). Neurotrophic and neuroprotective actions of ginsenosides Rb1 and Rg1. Planta Medica. 21(67), 533–537.
- Sengupta, S., Toh, S.A. et al. (2004). Modulating angiogenesis: The Yin and the Yang in ginseng. Circulation. 4(11), 1219–1225.
- Song, Z., Johansen, H.K. et al. (1997). Ginseng treatment reduces bacterial load and lung pathology in chronic Pseudomonas aeruginosa pneumonia in rats. Antimicrobial agents and chemotherapy. 41(5), 961–964.
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