Oil tea improves glucose and lipid levels and alters gut microbiota in type 2 diabetic mice
Introduction
Diabetes mellitus is a major public health problem in China, with a diabetes prevalence of 10.9% reported in the 2013 nationwide survey [1]. Prevention and treatment of diabetes thus represents a major challenge of modern society in China. Efforts to find “natural” or alternative medicines have increased markedly over the last several years, although the clinical efficacy of these are either mixed or wholly absent. In the province-wide nutrition survey conducted in Guangxi Province, China from 2013–2014, a 1.4% (9/647) prevalence of diabetes was found in an area which has a high oil tea consumption, Gongcheng Yao Autonomous County. This prevalence was much lower than the average frequency of diabetes in Guangxi [2] and in China [1]. This area has a cultural preference for frequent consumption of oil tea, used as both a common beverage and a base for multiple meals during the day, in addition to using it for the treatment and prevention of multiple aliments [3]. Green tea and ginger, as the main ingredients of oil tea and traditional herbal medicine [4], have each been demonstrated to exert antidiabetic effects, including in animal experiments [5], [6], [7], [8], cohort studies [9], [10], and randomized controlled trials [11], [12]. Oil tea, as a complex mixture of green tea, ginger, and oil, may therefore have antidiabetic effects.
Recent studies have shown that the beneficial effects of tea may be associated with gut microbiota [13], [14], [15]. Research shows that aberrant gut microbiota structure is associated with various metabolic disorders, including diabetes, obesity, and metabolic syndrome [16], [17]. It is also well recognized that gut microbiota responds to fluctuations in dietary composition [18] and reciprocally, changes in the microbiome have profound effects on the host. Potentially, by positively modulating the gut microbiota, results may have a beneficial impact on overall health, including diabetes-related outcomes.
In the present study, we investigated the effects of oil tea on type 2 diabetes and its subsequent effect on the composition of gut microbiota. The oil tea was prepared as usually consumed. We hypothesized that oil tea exerts antidiabetic effects and induces alterations in gut microbiota. To investigate this hypothesis, a genetic model of type 2 diabetes, db/db mice was used for oil tea treatment. Levels of fasting and postprandial blood glucose and serum lipid were measured, 16S rRNA genes were sequenced, and the response of gut microbiota to oil tea treatment was examined.
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Preparation of oil tea
Oil tea was prepared using a modification of the local manufacturing method of Gongcheng Yao Autonomous County, Guangxi Province, China [19]. Briefly, oil tea contains green tea, ginger, peanut, cooking oil, and salt with the proportion of 9:10:5:2:1. The manufacturing process is as follows. First, soaked green tea leaf was stir-fried and beaten with ginger, peanut, and cooking oil in a hot iron pot for three minutes; second, hot water and salt were added; and third, the mixture was boiled for
Main nutrition composition of oil tea
As shown in Table 2, oil tea contains very high concentrations of tea polyphenols (2463.5 mg/kg) and caffeine (377 mg/kg). Appreciable concentrations of [6]-gingerol (29.8 mg/kg) and manganese (5 mg/kg) were also detected. Meanwhile, less than 1% of the NRV of proteins and carbohydrates were detected, and oil tea had low energy content (33.19KJ/100 g).
Effect of oil tea on FBG
As shown in Fig. 1, lower FBG levels were observed in both the oil tea and MET treatment groups during the 8-week experiment, and a significant
Discussion
In this study, we found for the first time that oil tea, a traditional tea beverage consumed in the minority areas of Guangxi, China, has antidiabetic effects, such as lowering FBG levels and improving glucose tolerance. Oil tea treatment also resulted in significantly reduced TC, LDL, and TG levels and significantly modulated the composition of gut microbiota.
The medicinal properties of green tea and ginger have long been recognized in China, since having been recorded in the “Compendium of
Acknowledgment
This work was supported by the National Natural Science Foundation of China (No.81660540), Guangxi Natural Science Foundation (Grant No. 2015GXNSFCA139010), and Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Personnel of China (No. [2016] 176). The authors declare that they have no conflicts of interest.
References (55)
- et al.
Effect of green tea on glucose control and insulin sensitivity: a meta-analysis of 17 randomized controlled trials
Am J Clin Nutr
(2013) - et al.
The effect of ginger powder supplementation on insulin resistance and glycemic indices in patients with type 2 diabetes: a randomized, double-blind, placebo-controlled trial
Complement Ther Med
(2014) - et al.
Nutritional aspects of manganese homeostasis
Mol Aspects Med
(2005) - et al.
Effects of lipids and lipoproteins on diabetic foot in people with type 2 diabetes mellitus: a meta-analysis
J Diabetes Complications
(2014) - et al.
Traditional Chinese medicine network pharmacology: theory, methodology and application
Chin J Nat Med
(2013) - et al.
Ginger (Zingiber officinale roscoe): a hot remedy for cardiovascular disease?
Int J Cardiol
(2009) - et al.
Comparison of gut microbiota in adult patients with type 2 diabetes and healthy individuals
Microb Pathog
(2017) - et al.
Substituting whole grains for refined grains in a 6-wk randomized trial has a modest effect on gut microbiota and immune and inflammatory markers of healthy adults
Am J Clin Nutr
(2017) - et al.
Prevalence and control of diabetes in Chinese adults
JAMA
(2013) - et al.
Non-obese diabetes and its associated factors in an underdeveloped area of South China, Guangxi
Int J Environ Res Public Health
(2016)
Yao tea and disease preventiona and ailment treatment
J Med Pharm Chin Minorities
Compendium of Materia Medica
Diet supplementation with green tea extract epigallocatechin gallate prevents progression to glucose intolerance in db/db mice
Nutr Metab (Lond)
Oral green tea catechins transiently lower plasma glucose concentrations in female db/db mice
J Med Food
Effect of green tea extract/poly-gamma-glutamic acid complex in obese type 2 diabetic mice
Diabetes Metab J
Zingiber officinale and type 2 diabetes mellitus: evidence from experimental studies
Crit Rev Eukaryot Gene Expr
Tea consumption and risk of type 2 diabetes: a dose-response meta-analysis of cohort studies
Br J Nutr
Tea consumption and risk of type 2 diabetes: a meta-analysis of cohort studies
J Gen Intern Med
Kudingcha and Fuzhuan brick tea prevent obesity and modulate gut microbiota in high-fat diet fed mice
Mol Nutr Food Res
Fermented green tea extract alleviates obesity and related complications and alters gut microbiota composition in diet-induced obese mice
J Med Food
A metagenomics approach to the intestinal microbiome structure and function in high fat diet-induced obesity mice fed with oolong tea polyphenols
Food Funct
Gut microbiota, obesity and metabolic disorders
Minerva Gastroenterol Dietol
Gut microbiota and metabolic disorders
Diabetes Metab J
Diet rapidly and reproducibly alters the human gut microbiome
Nature
Study on the scientific connotation and industrial development of oil tea in Gongcheng Yao Autonomous County, Guangxi
J Med Pharm Chin Minorities
GB/T 8312–2008 Tea-Determination of tea poyphenols content in foods
GB/T 5009–2003 Determination of minerals in foods
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The authors contributed equally.