Phytomedicines used in the treatment of metabolic syndrome

Metabolic syndrome is an insidious cluster of conditions that occur together, increasing the risk of heart disease, stroke and type 2 diabetes. These conditions include high blood pressure, raised blood sugar levels, excess body fat around the waist, and abnormal cholesterol or triglyceride levels.

Having just one of these conditions doesn't mean a diagnosis of metabolic syndrome. But it does mean a greater risk of serious disease. And if more than one of these conditions arises, the risk of complications such as type 2 diabetes and heart disease, rises even higher.

In New Zealand the prevalence of diabetes mellitus continues to increase, with an estimated 253,000 diagnosed predominantly with diabetes type 2 in 2018¹. Within this population, Māori and Pacific populations make up three times more of the cases than other New Zealand ethnicities.  Disturbingly, children are increasingly being diagnosed².

Complications of diabetes include both microvascular and macrovascular conditions, such as retinopathy, nephropathy, neuropathy, cardiovascular disease, cerebrovascular accidents, leg ulcers and peripheral vascular disease.

As with many chronic health conditions, Medical Herbalists and Naturopaths have an arsenal of tools to empower our clients to prevent, treat, or better manage metabolic syndrome and associated conditions.  Although a great deal can be achieved through dietary advice and lifestyle interventions to manage stress and weight, there are a plethora of hypoglycaemic, hypolipidemic, hypocholesterolaemic, antidiabetic, trophorestorative, neuroprotective, anti-inflammatory, adaptogenic and nervine herbs that can be utilised.

Bitter Melon fruit (Momordica charantia)

Actions: Anti-diabetic, anti-obesity, hypoglycaemic, hyptotensive, hypocholesterolemic, anti-inflammatory, antioxidant.

Research shows the effectiveness of Bitter Melon in the treatment of diabetes, obesity and metabolic syndrome.  In vitro and animal studies, have demonstrated Bitter Melon’s blood-glucose lowering effects, enhancing skeletal and peripheral glucose uptake, inhibiting intestinal glucose uptake via glucosidase inhibition, improving glucose tolerance and insulin sensitivity, suppressing gluconeogenic enzymes and preserving pancreatic islet cells and their functions^3,4,5,6,7. 

Bitter Melon has also shown protective effects against diabetes-related complications, including diabetic cardiomyopathy caused by chronic hyperglycaemia^8,9. Various animal studies have indicated a significant reduction in systolic and diastolic blood pressure as well as total cholesterol and triglyceride lipid levels^5,8,10. In addition, its antioxidant and vasoprotective phenolic and flavonoid compounds reduce lipid peroxide levels and associated tissue damage, increase vasodilating nitric oxide (NO) levels and increase enzyme nitric oxide synthase (eNOS) and superoxide dismutase activity^8,10.

Gymnema (Gymnema sylvestre)

Gymnema is a well-known antidiabetic and hypoglycaemic herb, commonly used as a single herb to suppress sugar cravings.  It also combines well with Cinnamon as a hypoglycaemic.  This herb promotes islet β cell regeneration, making it useful for both Type 1 and Type 2 Diabetes mellitus.

A 1990 clinical trial found that combined treatment of Gymnema with insulin reduced the insulin dosage by 50% or more in 27 Type 1 diabetes patients. An aqueous extract of its leaves at 200 mg kg−1 day−1 reduced the level of HbA1c and lowered triglyceride levels, in both type 1 and type 2 diabetic patients.  Its higher dose at 400 mg kg−1 day−1 given to diabetic patients together with glyburide or tolbutamide reduced dose requirements for the drug which was even discontinued in some cases¹¹.  

Goats Rue (Galega officinalis)

Goat’s Rue is a hypoglycaemic herb used in the management of type 2 diabetes.  You may know that metformin, an oral hypoglycaemic drug and commonly used to treat diabetes type 2,is derived from galegine, a constituent found in Goats Rue¹².  This herb combines well with Fenugreek. Several mice studies also show Goat’s Rue to reduce weight and body fat^{13, 14, 15}. 

Kudzu (Pueraria lobata)

This hypoglycaemic herb is indicated and used in Traditional Chinese Medicine for metabolic syndrome and diabetes¹⁶. Of its many constituents, isoflavonoids and triterpenoids are predominant.  Evidence indicates that isoflavonoids, in particular puerarin, are responsible for Kudzu’s anti-diabetic effects¹⁷.

A 2016 study investigated how Kudzu ethanol extract suppressed weight gain in ovariectomized mice.  The results indicated that weight gain and serum glucose levels were significantly reduced in mice that consumed Kudzu ethanol extract (5 or 20 mg/kg/day) or puerarin (20mg/kg/day) ¹⁸.

Green Tea (Camellia sinensis)

Green tea consumption has been associated with decreased leptin levels, reduced calorie intake, enhanced energy expenditure, increased fat oxidation and thermogenesis, and therefore a reduction in body weight ^19,20,21.

Short term interventional studies have demonstrated positive effects for a catechin and caffeine combination, this increasing energy expenditure and fat oxidation over 24 hours in healthy men compared to both caffeine-only and placebo controls²⁰. Longer-term studies demonstrated a standardised (25% catechins) green tea ethanolic extract reduced weight in moderately obese subjects by 4.6% and waist circumference by 4.5% after three months²². Green tea and its extracts modify glucose metabolism beneficially in experimental models of type 2 diabetes mellitus, with in vitro evidence demonstrating ECGC (Epigallocatechin gallate) mimics insulin, reduces gluconeogenic gene expression and cytokine induced β-cell damage. In vivo studies have demonstrated its ability to downregulate hepatic glucose production, improve insulin sensitivity, and reduce lipogenic enzymes and circulating triglyceride and cholesterol levels^19,23.

Ginkgo (Ginkgo biloba)

A well-known neuroprotective herb, Ginkgo also has a role to play in helping to prevent complications of diabetes type 2. In a clinical trial where ginkgo was added to the oral hypoglycaemic drug metformin for 90 days, blood levels of fasting glucose, insulin, and HbA1c , whose elevation is linked to risks of diabetic complications, showed a greater reduction in the combined ginkgo-metformin treatment group, than with metformin treatment alone (24).

This blog has focussed on herbs used to manage metabolic syndrome and associated conditions.  In addition to the herbs profiled in this article, adaptogens and nervines should form a key component of the long-term glycaemic management approach due to the intrinsic link between stress and insulin resistance.  For example, Codonopsis pilosula, Panax Quinquefolium and Withania somnifera.
 

References:

1. Diabetes. Retrieved from https://www.hqsc.govt.nz/our-programmes/health-quality-evaluation/projects/atlas-of-healthcare-variation/diabetes/, 19^th March 2020.
2. About diabetes.  Retrieved from https://www.health.govt.nz/our-work/diseases-and-conditions/diabetes/about-diabetes, 12^th May 2014.
3. Yarnell E et al, Clinical Botanical Medicine (2^nd Ed. rev), 2009.
4. Singh J et al, Open Chem Med; 5(Suppl 2):70-7, 2011.
5. Taylor L, Herbal Secrets of the Rainforest (2^nd ed.), 2002
6. Rizvi S.I et al, J Diabetes Res; 2013:712092, 2013.
7. Urnler A.B. et al, J Agr Faculty of Uludag Uni; 26(2): 65-69, 2012.
8. Abas R et al, EXCLI J 2015 Jan 30; 14:179-189.
9. Boudina S et al, Rev Endocr Metab Disord 2010; 11(1):31-3
10. Mahdi A.A et al, Indian J Clin Biochem; 18(2):8-15.
11. Shanmugasundaram E.R.B et al, Journal of Ethno Pharmacology; 30 (1990), 281-294.
12. Hadden D.R. J R Coll Physicians Edinb 2005; 35:258–260.
13. Pali P et al. J Pharm Pharmacol; 1999 Nov;51(11):1313-9. doi: 10.1211/0022357991776895.
14. Mooney M.H et al. Br J Pharmacol; 2008 Apr;153(8):1669-77. doi: 0.1038/bjp.2008.37.
15. Coxon G.D et al. J Med Chem; 2009 Jun 11;52(11):3457-63.  doi: 10.1021/jm8011933.
16. Luo Q et al. China Journal of Chinese Materia Medica; 2007; 32,1141-1144.
17. Wong Ka H et al. Journal of Ethnopharmacology. 2011; 134,584-607.
18. Tanaka T et al. J Nutr Sci Vitaminol (Tokyo); 2016;62(5):341-349. doi: 10.3177/jnsv.62.341.
19. Chacko S et al, Chinese Med 2010; 5(13):1-9
20. Ogle N, Aus J Med Herb 2009; 21(2):44-48
21. Hursel R et al, Int J Obesity 2009; 33(9):956-61
22. Chantre P et al, Phytomedicine 2002; 9(1):3-8
23. Suzuki Y et al, Proc Jpn Acad Ser B Phys Biol Sci 2012; 88(3):88-101
24. Aziz TA et al, Drug Des Devel Ther. 2018 Apr 5;12:735-742