Review Article

Role of Black Tea in Type 2 Diabetes Mellitus and Metabolic Syndrome Nirmalya Roy*1, Kingshuk Bhattacharjee2, Sandip Bandhopadhyaya1, Sirshendu Chatterjee1, Ashish Kumar Saha1, Ananya Chatterjee1, Arpita Saha1, Surmi Roy1 and Chittaranjan Maity1 1

KPC Medical College, 1F, Raja Subodh Chandra Mullick Road, Jadavpur, Kolkata, West Bengal, India 700032 2 Independent Medical Writer, 547, Dumdum Park, Kolkata, West Bengal, India 700055

ABSTRACT

Address for Correspondence KPC Medical College, 1F, Raja Subodh Chandra Mullick Road, Jadavpur, Kolkata, West Bengal, India 700032 E-mail: nirmalya3h @yahoo.co.in

Consumption of black tea has been popular widely across the world. Tea (Camellia sinensis) has been used as a daily beverage since time immemorial. Tea is mainly available in three variants, approximately 76% to 78% of the tea produced and consumed worldwide is black, 20%-22% is green and less than 2% is oolong. Tea is an excellent source of poly phenolic compounds, particularly flavonoids. The catechins, also known as polyphenols present in the tea are mainly ascribed for the beneficial effect of tea in type 2 diabetes and metabolic syndrome. These active components (catechins) constitute seven forms including epigalocatechingallate (EGCg).The purpose of this review will focus on the effect of black tea catechins extracted from the Camelliasinensis plant on type 2 diabetes and metabolic syndrome.It is hoped that black tea can be consumed in a suitable manner as a supplement to prevent the advancement of type 2 diabetes, metabolic syndrome along with imparting other health benefits as well. Keywords: Black tea, Metabolic syndrome, Insulin.

INTRODUCTION Black tea is now consumed everywhere across the globe and is believed to have many beneficial effect on the health.1 Notwithstanding many animal experiments have shown positive results, recently effectiveness of consumption of black tea on metabolic diseases are clearly demonstrated even in humans.2 Diabetes is a chronic disorder of carbohydrate, fat and

protein metabolism characterized by increased fasting and post prandial blood sugar levels.2 The global prevalence of diabetes is projected to increase, from 4% in 1995 to 5.4% by the year 2025.2 World Health Organization has anticipated that the major surge will occur in developing countries.3

American Journal of Phytomedicine and Clinical Therapeutics

www.ajpct.org

Roy et al___________________________________________________ ISSN 2321 – 2748 Inflammations and Diabetes Various inflammatory pathways are indicated in the progression of type-2 diabetes which may accelerate insulin resistance and progressive beta cells dysfunction. In diabetic pathophysiology, the pancreatic beta cells are unable to secrete adequate insulin to overcome insulin resistance, thereby causing persistent hyperglycemia that may result in many macrovascular and microvascular complications. Recently, growing body of evidence have demonstrated that the propensity of developing type 2 diabetes is significantly associated with low-grade inflammation.4,5 Moreover, nowadays chronic subclinical inflammation is accepted as an integral part of the insulin resistance syndrome6,7 and also significantly correlate to features of the metabolic syndrome.8,9 Many observational prospective studies have demonstrated that approximately 5-10% of the pre-diabetic subjects become diabetic every year.10 Long-term inflammation of low grade intensity during pre-diabetic state facilitate onset of diabetes.4Recent epidemiological evidences also affirm the facts that inflammatory markers predict the development of diabetes and glucose disorders.11 Two major pro-inflammatory cytokines TNF-a and IL-1ß have been culpably involved for obesity associated insulin resistance and pathogenesis of Type 2 diabetes (T2DM). Evidences From Clinical Trials Evidences generated from recent epidemiological studies demonstrates that daily consumption of black tea may be significantly associated with the reduced pro-inflammatory stress by altering the level of specific cytokines. In a recent study by Chatterjee et al., the authors had seen the effect of black tea on nine pre-diabetic subjects with metabolic syndrome. Their results demonstrated that the black tea AJPCT[3][08][2015] 570-574

consumption have a potential role in down regulating the serum lipid peroxides level, pro-inflammatory cytokines (TNF-a, IL-1ß) level and also may up regulate the antiinflammatory cytokine (IL-10) significantly.11 In addition, consumption of black tea for one month had resulted in significant changes (p