The Pharmacological Activity of Camellia sinensis (L.) Kuntze on Metabolic and Endocrine Disorders: A Systematic Review

Abstract

Tea made from Camellia sinensis leaves is one of the most consumed beverages worldwide. This systematic review aims to update Camellia sinensis pharmacological activity on metabolic and endocrine disorders. Inclusion criteria were preclinical and clinical studies of tea extracts and isolated compounds on osteoporosis, hypertension, diabetes, metabolic syndrome, hypercholesterolemia, and obesity written in English between 2014 and 2019 and published in Pubmed, Science Direct, and Scopus. From a total of 1384 studies, 80 reports met inclusion criteria. Most papers were published in 2015 (29.3%) and 2017 (20.6%), conducted in China (28.75%), US (12.5%), and South Korea (10%) and carried out with extracts (67.5%, especially green tea) and isolated compounds (41.25%, especially epigallocatechin gallate). Most pharmacological studies were in vitro and in vivo studies focused on diabetes and obesity. Clinical trials, although they have demonstrated promising results, are very limited. Future research should be aimed at providing more clinical evidence on less studied pathologies such as osteoporosis, hypertension, and metabolic syndrome. Given the close relationship among all endocrine disorders, it would be of interest to find a standard dose of tea or their bioactive constituents that would be beneficial for all of them.

Tea intake and cardiovascular disease: an umbrella review

“…Thirty-seven publications were subject to dual full-text screening [ 2 , 3 , 11 , 18–51 ]. We excluded 14systematic reviews for the following reasons: one was a conference abstract [ 35 ], one was a non-English publication [ 44 ], one publication included only extracts or capsules [ 39 ], one study combined tea and wine with tea in the analyses [ 37 ], three were not systematic reviews [ 41 , 42 , 45 ], one publication did not assess tea intake [ 43 ], one publication was a systematic review of in vitro studies [ 36 ], one publication included CVD markers only as a secondary outcome [ 38 ], one publication was a protocol manuscript [ 51 ], two publications did not contain data [ 47 , 48 ], and one publication search predated 2010 [ 40 ]. Twenty-three publications [ 2 , 3 , 11 , 18–34 , 46 ] remained after dual full-text screening and searching the reference lists of included systematic reviews.…”

Phytochemicals as Potential Epidrugs in Type 2 Diabetes Mellitus

“…Finally, there are some preclinical and clinical studies exploring the effect of green and black tea in T2DM. Studies were performed between 12 weeks and 18 months with doses/ day between 200 mg/day and 2.5 g/3 times for day (127). For example, in a clinical trial for 12 weeks performed in 32 T2DM patients and 28 controls, 1 g/day of green tea infusion reduced HbA1c (86,88).…”

Exploration of the Potential of Terrestrial and Marine Biodiversity for the Development of Local Nutraceutical Products: A Case for Mauritius

“…Leaves and leaf buds [7,8,10,14,30,160,161] Green Tea: antioxidant, antidiabetic, and ripe fruits can be utilized. Indeed, several parts of the C. papaya plant are used in traditional medicine in Mauritius: the ripe fruit for stomach/peptic ulcer and constipation, hypertension, high cholesterol level and as anti-pimple, anti-pigmentation and skin moisturizer; the green fruit for stomach and duodenal ulcers; the seeds for intestinal worms; the roots for pain in joints, muscles and arthritis; and the latex as vermifuge.…”

“…[223] Mauritian tea: A panoply of bioactive constituents Tea, Camellia sinensis (L.) Kuntze, belonging to the family eaceae, is native to Southeast Asia. [161] Tea made from the leaves of C. sinensis is a widely consumed beverage around the world and there are three major varieties of tea -green, black, and oolong. [161,231,232] e difference between the teas lies in their processing; green tea is produced from unfermented leaves, the leaves of oolong tea are partially fermented, while the leaves are fully fermented to prepare black tea.…”

“…[161] Tea made from the leaves of C. sinensis is a widely consumed beverage around the world and there are three major varieties of tea -green, black, and oolong. [161,231,232] e difference between the teas lies in their processing; green tea is produced from unfermented leaves, the leaves of oolong tea are partially fermented, while the leaves are fully fermented to prepare black tea. [161,232,233] Locally, ethnopharmacological usage of tea include as tonic, stimulant, astringent, in the treatment of conjunctivitis, eye infection, cataract, diarrhea, type 2 diabetes mellitus, high level of cholesterol, and as anti-dark circles and antiwrinkle agent.…”