Re: 타우린 대사증후군, 만성염증 치료 2024 nature RCT 논문

[문형철]

Taurine, a sulfur-containing amino acid preval‎ent in various tissues, exhibits significant antioxidant properties through multiple mechanisms:

1. Regulation of Mitochondrial Function:

Taurine modulates mitochondrial protein synthesis, enhancing the activity of the electron transport chain. This regulation prevents the formation of bottlenecks in electron transport, thereby reducing the diversion of electrons that can lead to superoxide production. By maintaining efficient electron flow, taurine helps mitigate oxidative stress within mitochondria.

pubmed.ncbi.nlm.nih.gov

2. Modulation of Antioxidant Enzyme Activity:

Taurine has been shown to upregulate the activity of endogenous antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). This enhancement bolsters the body's defense against reactive oxygen species (ROS), thereby reducing oxidative damage.

spandidos-publications.com

3. Inhibition of NADPH Oxidase:

Taurine suppresses the activity of NADPH oxidase, an enzyme complex that is a significant source of ROS in cells. By inhibiting this enzyme, taurine reduces the production of ROS, thereby diminishing oxidative stress.

pmc.ncbi.nlm.nih.gov

4. Scavenging of Hypochlorous Acid:

Taurine directly scavenges hypochlorous acid (HOCl), a potent oxidant produced by the immune system during inflammatory responses. This reaction leads to the formation of taurine chloramine, a less reactive and more stable compound, thereby reducing oxidative damage.

mdpi.com

Through these multifaceted actions, taurine effectively mitigates oxidative stress, contributing to cellular protection and overall health.

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• Open access
• Published: 16 May 2024

Taurine reduces the risk for metabolic syndrome: a systematic review and meta-analysis of randomized controlled trials

• Chih-Chen Tzang, 
• Liang-Yun Chi, 
• Long-Huei Lin, 
• Ting-Yu Lin, 
• Ke-Vin Chang, 
• Wei-Ting Wu & 
• Levent Özçakar 

Nutrition & Diabetes volume 14, Article number: 29 (2024) Cite this article

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Abstract

Background

Metabolic syndrome (MetS) is a cluster of interconnected risk factors that significantly increase the likelihood of cardiovascular disease and type 2 diabetes. Taurine has emerged as a potential therapeutic agent for MetS. This meta-analysis of randomized controlled trials (RCTs) aimed to eval‎uate the effects of taurine supplementation on MetS-related parameters.

Methods

We conducted electronic searches through databases like Embase, PubMed, Web of Science, Cochrane CENTRAL, and ClinicalTrials.gov, encompassing publications up to December 1, 2023. Our analysis focused on established MetS diagnostic criteria, including systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose (FBG), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C). Meta-regression explored potential dose-dependent relationships based on the total taurine dose administered during the treatment period. We also assessed secondary outcomes like body composition, lipid profile, and glycemic control.

Results

Our analysis included 1024 participants from 25 RCTs. The daily dosage of taurine in the studies ranged from 0.5 g/day to 6 g/day, with follow-up periods varying between 5 and 365 days. Compared to control groups, taurine supplementation demonstrated statistically significant reductions in SBP (weighted mean difference [WMD] = −3.999 mmHg, 95% confidence interval [CI] = −7.293 to −0.706, p = 0.017), DBP (WMD = −1.509 mmHg, 95% CI = −2.479 to −0.539, p = 0.002), FBG (WMD: −5.882 mg/dL, 95% CI: −10.747 to −1.018, p = 0.018), TG (WMD: −18.315 mg/dL, 95% CI: −25.628 to −11.002, p < 0.001), but not in HDL-C (WMD: 0.644 mg/dl, 95% CI: −0.244 to 1.532, p = 0.155). Meta-regression analysis revealed a dose-dependent reduction in DBP (coefficient = −0.0108 mmHg per g, p = 0.0297) and FBG (coefficient = −0.0445 mg/dL per g, p = 0.0273). No significant adverse effects were observed compared to the control group.

Conclusion

Taurine supplementation exhibits positive effects on multiple MetS-related factors, making it a potential dietary addition for individuals at risk of or already experiencing MetS. Future research may explore dose-optimization strategies and potential long-term benefits of taurine for MetS management.

초록

배경

대사증후군(MetS)은 심혈관 질환과 제2형 당뇨병의 발생 가능성을 크게 높이는 상호 연결된 위험 요소들의 집합체입니다. 타우린은 MetS의 잠재적 치료제로 부상하고 있습니다. 무작위 대조 시험(RCT)에 대한 이 메타 분석은 타우린 보충제가 MetS 관련 변수에 미치는 영향을 평가하는 것을 목표로 합니다.

방법

2023년 12월 1일까지의 출판물을 망라하여 Embase, PubMed, Web of Science, Cochrane CENTRAL, ClinicalTrials.gov 등의 데이터베이스를 통해 전자 검색을 실시했습니다. 저희의 분석은 수축기 혈압(SBP), 이완기 혈압(DBP), 공복 혈당(FBG), 중성지방(TG), 고밀도지단백 콜레스테롤(HDL-C) 등 확립된 MetS 진단 기준에 초점을 맞추었습니다. 메타 회귀분석은 치료 기간 동안 투여된 총 타우린 용량을 기준으로 용량 의존적 관계를 탐구했습니다. 또한 체성분, 지질 프로필, 혈당 조절과 같은 2차 결과도 평가했습니다.

결과

저희의 분석에는 25개의 RCT에 참여한 1024명의 참가자가 포함되었습니다.

연구에서 타우린의 일일 복용량은

0.5g/일에서 6g/일 사이였고,

추적 기간은 5일에서 365일 사이였습니다.

대조군과 비교했을 때, 타우린 보충제는 통계적으로 유의미한 SBP 감소(가중 평균 차이[WMD] = -3.999mmHg, 95% 신뢰 구간[CI] = -7.293~-0.706, p = 0.017), DBP 감소(WMD = -1. 509mmHg, 95% CI = -2.479 ~ -0.539, p = 0.002), FBG (WMD: -5.882mg/dL, 95% CI: -10.747 ~ -1.018, p = 0.018), TG (WMD: -18.315mg/dL, 95% CI: -25.628~-11.002, p<0.001), 그러나 HDL-C(WMD: 0.644mg/dl, 95% CI: -0.244~1.532, p=0.155)에는 영향을 미치지 않았습니다. 메타 회귀 분석 결과, DBP(계수 = -0.0108mmHg/g, p = 0.0297)와 FBG(계수 = -0.0445mg/dL/g, p = 0.0273)가 용량 의존적으로 감소하는 것으로 나타났습니다. 대조군과 비교했을 때, 유의미한 부작용은 관찰되지 않았습니다.

결론

타우린 보충제는

여러 가지 대사증후군 관련 요인에 긍정적인 영향을 미치기 때문에,

메트스 위험이 있거나 이미 메트스를 경험하고 있는 사람들에게

잠재적인 식이 보충제로 권장될 수 있습니다.

향후 연구에서는

메트스 관리를 위한 타우린의 용량 최적화 전략과

잠재적인 장기적 이점을 탐구할 수 있을 것입니다.

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Introduction

Metabolic syndrome (MetS) poses a significant global health challenge, affecting over one billion people [1]. This cluster of interconnected risk factors is diagnosed by the presence of: (1) abdominal obesity with increased waist circumference, (2) high blood pressure, (3) high fasting blood glucose (FBG) levels, (4) high triglyceride (TG) levels, and (5) a low level of high-density lipoprotein cholesterol (HDL-C) [2]. MetS significantly increases the risk of various health problems, including cardiovascular disease, stroke, and type 2 diabetes [3]. Its development is associated with factors like insulin resistance, chronic inflammation, and neurohormonal activation [3].

Taurine (2-aminoethanesulfonic acid), a sulfur-containing amino acid, has gained scientific interest due to its potential to modulate various physiological processes. It is primarily obtained through diet, particularly from foods like shellfish, dark meat, and some energy drinks [4]. Abundant in tissues like the heart, retina, liver, muscle, and platelets, taurine plays crucial roles in osmoregulation, mitochondrial function, maintenance of cell membrane stability, antioxidative defense mechanisms, and regulating cation balance [4].

In addition to its fundamental functions, taurine shows promise for regulating key metabolic parameters associated with MetS. It plays a significant role in controlling lipid metabolism by conjugating with bile salts [4]. Studies have also suggested its potential to improve glycemic markers, including FBG, serum insulin levels, and glycated hemoglobin (HbA1c) [5]. Moreover, taurine may exert anti-inflammatory effects by inhibiting the renin-angiotensin system, a key factor in the development of cardiovascular diseases and obesity [6]. Therefore, taurine has the potential to positively affect MetS.

Despite numerous clinical studies demonstrating the diverse health benefits of taurine, inconsistencies in clinical outcomes make it challenging to definitely determine whether taurine reduces the risk of MetS [7, 8]. To address this knowledge gap, we conducted a meta-analysis of randomized controlled trials (RCTs) to systematically analyze the effects of taurine on modifying the parameters associated with MetS.

소개

대사증후군(MetS)은 전 세계적으로 심각한 건강 문제를 야기하고 있으며, 10억 명 이상의 사람들에게 영향을 미치고 있습니다 [1]. 상호 연결된 위험 요소의 집합은 다음의 존재로 진단됩니다:

(1) 허리 둘레가 증가된 복부 비만,

(2) 고혈압,

(3) 공복 혈당(FBG) 수치,

(4) 중성지방(TG) 수치,

(5) 저밀도지단백 콜레스테롤(HDL-C) 수치 [2].

메트포르민은 심혈관 질환, 뇌졸중, 제2형 당뇨병을 포함한 다양한 건강 문제의 위험을 크게 증가시킵니다 [3]. 메트포르민의 발생은 인슐린 저항성, 만성 염증, 신경호르몬 활성화와 같은 요인과 관련이 있습니다 [3].

황 함유 아미노산인 타우린(2-aminoethanesulfonic acid)은

다양한 생리적 과정을 조절할 수 있는 잠재력 때문에

과학계의 관심을 끌고 있습니다.

타우린은

주로 식단을 통해 섭취할 수 있으며,

특히 조개류, 붉은 살코기, 일부 에너지 드링크에 많이 함유되어 있습니다 [4].

심장, 망막, 간, 근육, 혈소판과 같은 조직에 풍부하게 함유되어 있는

타우린은

삼투압 조절,

미토콘드리아 기능,

세포막 안정성 유지,

항산화 방어 메커니즘,

양이온 균형 조절에 중요한 역할을 합니다 [4].

타우린은 기본적인 기능 외에도 대사증후군과 관련된 주요 대사 매개변수를 조절하는 데 유망한 것으로 나타났습니다. 담즙산염과 결합하여 지질 대사를 조절하는 데 중요한 역할을 합니다 [4]. 또한, FBG, 혈청 인슐린 수치, 당화 헤모글로빈(HbA1c)을 포함한 혈당 지표 개선에 도움이 될 수 있다는 연구 결과도 있습니다 [5]. 뿐만 아니라, 타우린은 심혈관 질환과 비만의 주요 원인인 레닌-안지오텐신 시스템을 억제함으로써 항염 효과를 발휘할 수 있습니다 [6]. 따라서 타우린은 대사증후군에 긍정적인 영향을 미칠 가능성이 있습니다.

타우린의 다양한 건강상의 이점을 입증하는 수많은 임상 연구가 있지만, 임상 결과의 일관성이 부족하여 타우린이 대사증후군의 위험을 감소시키는지 여부를 확실히 판단하기가 어렵습니다 [7, 8]. 이러한 지식 격차를 해소하기 위해, 우리는 대사증후군과 관련된 변수를 수정하는 데 있어 타우린의 효과를 체계적으로 분석하기 위해 무작위 대조 시험(RCT)의 메타 분석을 실시했습니다.

Materials and methods

General guidelines

This meta-analysis adhered to the most recent revision of Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines (Table S1) [9]. The review was registered on Inplasy.com under number (INPLASY2023120081). Two authors (T.-C.C. and C.-L.Y.) conducted independent electronic searches in Embase, PubMed, Web of Science, Cochrane CENTRAL, and ClinicalTrials.gov databases using the following keywords (“taurine” OR “taufon”) AND (“metabolic syndrome” OR “diabetes mellitus” OR “obesity” OR “hypertension” OR “dyslipidemia” OR ‘hyperglycemia’). The search covered the inception of each database until December 1, 2023. The detailed search methodology is provided in the Supplementary Material (Table S2). The identified titles and abstracts were initially screened by the two authors to determine their eligibility, followed by a full-text review where necessary. We also manually searched additional databases and checked the reference lists of relevant meta-analyses. This study included publications in all languages.

Inclusion and exclusion criteria

This meta-analysis followed the PICO (population, intervention, comparison, and outcome) settings design: P, human participants; I, taurine supplementation; C, supplementation (including placebo) other than taurine; and O, parameters associated with the diagnosis of MetS.

We included (1) RCTs employing pure taurine and its compounds as the treatment arm, (2) trials with a comparative arm using interventions other than taurine, and (3) studies providing data for pre- and post-intervention assessments of at least one outcome related to MetS.

We excluded (1) non-RCTs, including quasi-experimental studies such as real world observations, trials without a comparing placebo, retrospective studies, cohort studies and case reports; (2) studies with short follow-up periods unlikely to capture effects on MetS (e.g., less than 24 h); (3) trials using herbal treatments with unclear active ingredients; (4) studies lacking data for pre- and post-intervention endpoints; and (5) studies not investigating outcomes of interest.

Trials with follow-up durations less than 24 h and trials with unclear active ingredients were excluded as they did not align with the purpose of the study. Studies lasting less than 24 h primarily focus on the immediate effects of energy drinks, such as changes in heart rate, so we have opted to exclude them. Furthermore, studies that lacked precise quantification of active ingredients or failed to provide a comprehensive list of effective ingredients were excluded since we could accurately attribute observed effects solely to taurine.

Methodological quality appraisal

The methodological quality of the included studies was assessed using the Cochrane risk of bias tool for RCTs (RoB 2, London, United Kingdom), which eval‎uates six main domains: randomization process, intervention adherence, missing outcome data, outcome measurement, selective reporting, and overall risk of bias [10]. Within the RoB 2 framework, intervention adherence can be assessed using two approaches: intention-to-treat and per-protocol. We opted for the per-protocol approach because most RCTs only report data from participants who completed the entire trial course [10].

Primary and secondary outcome

The primary outcomes of this investigation were changes in (1) systolic blood pressure (SBP), (2) diastolic blood pressure (DBP), (3) FBG, (4) TG, and (5) HDL-C. The secondary outcomes included: (1) body composition measures like body weight (BW) and body mass index (BMI), (2) lipid profiles including total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), (3) glycemic profiles including HbA1c, homeostatic model assessment (HOMA), and fasting insulin, and (4) adverse effects. To accommodate studies with no reported adverse events, the number of cells with zero events was adjusted to 0.5 [11].

Data extraction and management

Two independent authors (T.-C.C. and C.-L.Y.) extracted data from the reviewed studies, including demographics, research design, details of taurine and control regimens, and outcome values. To avoid misinterpretation of effects, they carefully considered the direction of the scales used in each trial. In cases where data was missing from published studies, attempts were made to contact the corresponding authors to obtain the original data. Data extraction, conversion, and merging of outcomes from different study arms with varying taurine dosages were performed in accordance with the Cochrane Handbook for Systematic Review of Interventions and relevant medical literature [12,13,14]. For statistical analysis, the outcomes reported after the intervention were extracted, assuming data were available for multiple time points post-treatment.

Statistical analyses

This meta-analysis was conducted using Comprehensive Meta-Analysis software (version 3; Biostat, Englewood, NJ, United States) due to the heterogeneous nature of the study populations [15]. For all continuous outcomes, the weighted mean difference (WMD) and its 95% confidence interval (CI) were calculated. Odds ratios and their corresponding 95% CIs were used to analyze categorical outcomes (i.e., the rates of treatment-related adverse events), such as the rates of treatment-related adverse events. The effects of outcomes were assessed using WMD, with respective units dependent on the variable. This metric illustrates the magnitude of change observed across the entire taurine intervention, regardless of dose and duration.

Heterogeneity between studies was assessed using I2 and Cochran’s Q statistics. I2 values of 25%, 50%, and 75% were considered indicative of low, moderate, and high heterogeneity, respectively [16]. To investigate potential dose-dependent relationships between taurine and primary outcomes, meta-regression analyses were conducted using the total taurine dose administered throughout the treatment period and the daily dosage. The total dose was calculated as the product of the duration of intake multiplied by the dosage per day. Thus, the coefficient represents the average effect per gram of administered taurine.

A one-study removal sensitivity analysis was conducted to assess whether excluding a specific trial significantly altered the overall effect size [11]. To investigate potential publication bias, we visually examined the distribution of effect sizes in a funnel plot and assessed the statistical significance of Egger’s regression test [9].

Results

Study selection

Our initial search yielded 2517 publications. After removing duplicates and screening titles and abstracts, we deemed 2476 articles irrelevant and discarded them. We then conducted a full-text review of the remaining 41 studies.

Thirteen articles were excluded for various reasons (Table S3): four weren’t RCTs, one used an herbal treatment with unverified active compounds, one was a poster abstract lacking data, six did not report outcomes aligned with our research focus, and one only administered a single dose of the intervention. This resulted in the inclusion of 25 studies [7, 8, 17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39] in our final quantitative analysis (Fig. 1). Data extraction details for these RCTs are presented in Tables 1 and 2.

Fig. 1

The PRISMA flow diagram of the screening and review process.

Full size image

Table 1 Summary of trials retrieved to investigate the impact of taurine on metabolic syndrome.

First author & yearCountryPopulationParticipants (F/M)AgeFunding/grants/support

Azuma [22]	Japan	Congestive heart failure	58 (30/28)	38 - 89	N/A
Azuma [21]	Japan	Congestive heart failure	14 (5/9)	68.71 ± 9.10	Osaka University Medical School
Fujita [27]	Japan	Borderline hypertension	19 (N/A)	20 - 25	N/A
Azuma [23]	Japan	Idiopathic dilated cardiomyopathy	17 (6/11)	N/A	N/A
Mizushima [30]	Japan	Healthy male volunteers	20 (0/20)	18 - 29	N/A
Zhang [8]	Japan	Overweight or obese non-diabetic subjects	30 (16/14)	Taurine group 20.1 ± 2.0 Placebo group 20.4 ± 1.1	Taisho Pharmaceutical Co., Ltd., Japan
Spohr [7]	Denmark	Type 2 diabetes mellitus	18 (0/18)	40 ± 8	Steno Diabetes Center, Gentofte, Denmark, Aase and Ejnar Danielsens Foundation, Lyngby, Denmark
Moloney [31]	Ireland	Type 1 diabetes mellitus	19 (0/19)	28.0 ± 2.0	N/A
Beyranvand [25]	Iran	Heart failure with left ventricular ejection fraction less than 50%	29 (3/26)	60.57 ± 6.54	Shahid Beheshti Medical University
Arrieta [19]	Spain	Patients require amino-acid supplement after major surgical procedure	74 (21/53)	Taurine group: 48 – 90 Placebo group: 50 - 113	N/A
Hsieh [28]	China	Chronic alcoholic patients	30 (17/13)	Taurine group 59 ± 13 Placebo group 60 ± 12	Asia University (100-A-06), Chung Shan MedicalUniversity (CSMU-INT-102-12).
Rosa [34]	Brazil	Obese women	16 (16/0)	32 ± 2	National Council of Scientific and Technological Development (CNPq), State of Sao Paulo Research Foundation (FAPESP).
Averin [20]	Russia	Coronary heart disease/Heart valve defects	48 (12/36)	Taurine group: 49.79 ± 1.4 Placebo group 48.65 ± 1.5	N/A
Ra [33]	Japan	Healthy men	29 (0/29)	Taurine group: 25. 4 ± 1.0Placebo group: 25.2 ± 1.0	Japan Society for the Promotion of Science (JSPS)
Sun [37]	China	Prehypertensive individuals	86 (44/42)	56.75 ± 8.26	National Basic Research Program of China, National Natural Science Foundation of China
Ahmadian [17] a a (Journal of Dietary Supplements)	Iran	Heart failure	16 (N/A)	Taurine group: 60.12 ± 5.4 Placebo group: 60.13 ± 8.3	N/A
Ahmadian [18] b a (Ther Adv Cardiovasc Dis)	Iran	Heart failure	16 (N/A)	Taurine group: 60.12 ± 5.4 Placebo group: 60.13 ± 8.3	N/A
Schwarzer [35]	Austria	Patients with hepatic venous pressure gradient ≥12 mmHg	22 (8/14)	52 ± 11	N/A
Batitucci [24]	Brazil	Obese women	22 (22/0)	36.6 ± 6.4	Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES); The Sao Paulo Research Foundation (FAPESP)
Shari [36]	Iraq	Type 2 diabetes mellitus	80 (34/46)	Taurine group: 48.8 + 3.1 Placebo group: 50.2 ± 3.7	N/A
Van Hove [38]	USA	Inherited cystathionine -β-synthase deficient homocystinuria	36 (19/17)	8 - 50	Food and Drug Administration, Walter S. and Lucienne Driskill Foundation
Maleki [29]	Iran	Type 2 diabetes mellitus	45 (30/15)	Taurine group: 41.61 ± 6.63 Placebo group: 43.86 ± 7.06	Tabriz University of Medical Sciences, Tabriz, Iran
Esmaeili [26]	Canada	Type 2 diabetes mellitus	46 (32/14)b	Taurine group: 42.74 ± 7.21 Placebo group: 43.52 ± 6.94	N/A
Zaki [39]	Egypt	Peripartum cardiomyopathy	40 (40/0)	Taurine group: 31.1 ± 2.64 Placebo group: 30.85 ± 3.07	N/A
Moludi [32]	Iran	Type 2 diabetes mellitus	120 (97/23)	Taurine group: 52.13 ± 8.1 Placebo group: 53.08 ± 8.8	N/A

Full size table

Table 2 Summary of taurine interventions administered in the treatment arms of the trials.

First author & year	Daily Taurine dose (N)	Control (N)	Population	Duration	Taurine product/manufacturer
Azuma [22]	6 g/day (58)	Matching placebo (58)	Congestive heart failure	4 weeksc	Not mentioned
Azuma [21]	6 g/day (14)	Matching placebo (14)	Congestive heart failure	4 weeksc	Not mentioned
Fujita [27]	6 g/day (10)	Matching placebo (9)	Borderline hypertension	7 days	Not mentioned
Azuma [23]	3 g/day (7)	Active placebo (10)	Idiopathic dilated cardiomyopathy	6 weeks	Taurine sachet/Not mentioned
Mizushima [30]	6 g/day (11)	Matching placebo (9)	Healthy male volunteers	3 weeks	Taurine capsules/Taisho Pharmaceutical Co. Ltd.
Zhang [8]	3 g/day (15)	Comparable placebo (15)	Overweight or obese non-diabetic subjects	7 weeks	Taurine capsules/Jianli Pham Co., Beijing, China
Spohr [7]	1.5 g/day (18)	Matching placebo (44)	Type 2 diabetes mellitus	8 weeksc	Taurine capsules/Not mentioned
Moloney [31]	1.5 g/day (9)	Matching placebo (10)	Type 1 diabetes mellitus	14 daysc	Taurine tablet/Twinlab
Beyranvand [25]	1.5 g/day (15)	Matching placebo (14)	Heart failure with left ventricular ejection fraction less than 50%	2 weeks	Taurine capsules/Solgar, Leonia, NJ, USA
Arrieta [19]	1.6 g/dayb (35)	Comparable placebo (39)	Patients require amino-acid supplement after major surgical procedure	24 days	Tauramin 10%,/Laboratorios Grifols SA, Barcelona, Spain
Hsieh [28]	6 g/day (15)	Matching placebo (15)	Chronic alcoholic patients	3 months	Taurine capsules/Dokui Chemical Company (Taiwan)
Rosa [34]	3 g/day (8)	Matching placebo (8)	Obese women	8 weeks	Taurine capsules/Ajinomoto CO., INC., Limeira, SP,Brazil
Averin [20]	0.5 g/day (24)	Matching placebo (24)	Coronary heart disease/Heart valve defects	3 months	Taurine capsules/Pik-Pharma, Russian Federation
Ra [33]	6 g/day (15)	Matching placebo (14)	Healthy men	15 days	Taurine capsules/Taisho Pharmaceutical Co., Ltd., Japan
Sun [37]	1.6 g/day (42)	Matching placebo (20)	Prehypertensive individuals	12 weeks	Taurine capsules/Not mentioned
Ahmadian [17]a (Journal of Dietary Supplements)	1.5 g/day (8)	Matching placebo (8)	Heart failure	2 weeks	Taurine capsules/Solgar, Leonia, NJ, USA
Ahmadian [18]a (Ther Adv Cardiovasc Dis)	1.5 g/day (8)	Matching placebo (8)	Heart failure	2 weeks	Taurine capsules/Solgar, Leonia, NJ, USA
Schwarzer [35]	6 g/day (12)	Matching placebo (10)	Patients with hepatic venous pressure gradient ≥12 mm Hg	4 weeks	Taurine capsules/Not mentioned
Batitucci [24]	3 g/day (14)	Matching placebo (8)	Obese women	8 weeks	Taurine powder/Aminoethylsulfonic Acid, Ajinomoto®, São Paulo, SP
Shari [36]	1 g/day (40)	Matching placebo (40)	Type 2 diabetes mellitus	3 months	Taurine capsules/Jarrow’s formulas
Van Hove [38]	5 g/day (14)	Matching placebo (22)	Inherited cystathionine -β-synthase deficient homocystinuria	5 days	Not mentioned
Maleki [29]	3 g/day (23)	Matching placebo (22)	Type 2 diabetes mellitus	8 weeks	Taurine capsules/Karen Pharma and Food Supplement Co., Iran,
Esmaeili [26]	3 g/day (23)	Matching placebo (23)	Type 2 diabetes mellitus	8 weeks	Taurine capsules/Karen Pharmaceutical Co
Zaki [39]	0.6 g/day (20)	Comparable placebo (18)	Peripartum cardiomyopathy	5 days	10 ml/kg taurine solution/10% (Aminoven®, Fresenius‑Kabi, Egypt)
Moludi [32]	3 g/day (60)	Matching placebo (60)	Type 2 diabetes mellitus	8 weeks	Taurine capsules/Karen Food Supplement Co, Iran

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Study characteristic

Key features of the 25 RCTs, involving 1,024 participants, are summarized in Table 1. Conducted between 1983 and 2021 in diverse locations (Russia, Iran, Japan, Spain, Brazil, Canada, Ireland, China, Austria, Iraq, Denmark, the USA, and Egypt), the studies enrolled participants aged 8–113 years with a wide range of conditions. These included healthy individuals, post-surgical patients, and individuals with conditions such as heart failure, hypertension, coronary heart disease, heart valve defects, cardiomyopathy, type 1 diabetes mellitus, type 2 diabetes mellitus, obesity, alcoholism, and homocystinuria.

Quality assessment

Eighteen studies [8, 17,18,19,20,21,22,23,24,25, 27, 28, 30, 33,34,35,36,37,38] lacked information on allocation concealment, putting them at risk of bias. The remaining seven studies [7, 26, 29, 31, 32, 35, 39] had a low risk of bias, and none had a high risk of bias (Fig. S1, Table 3).

Table 3 Detailed quality assessment of the included studies using Cochrane risk of bias 2 tool.

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Primary outcomesEffects of taurine on SBP/DBP

Taurine supplementation significantly reduced SBP compared to the control group (WMD = −3.999 mmHg, 95% CI = −7.293 to −0.706, p = 0.017, I2 = 84.949) (Fig. 2a). This effect remained consistent even after excluding individual studies on the sensitivity analysis (Fig. S2a). Meta-analysis regression did not reveal a statistically significant linear relationship between total dose and SBP (coefficient = −0.024 mmHg per g, p = 0.113) (Fig. S3a), and a significant relationship between daily dose and SBP (coefficient = −1.1258 mmHg per g/day, p = 0.0055) (Fig. S4a).

Fig. 2

Forest plot of overall effects of taurine on systolic blood pressure (SBP) and diastolic blood pressure (DBP).

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Taurine significantly reduced DBP levels (WMD = −1.509 mmHg, 95% CI = −2.479 to −0.539, p = 0.002, I2 = 14.077) (Fig. 2b). Similar to SBP, this DBP reduction persisted in the sensitivity analysis (Fig. S2b). Moreover, meta-regression analysis showed a significant correlation between total dose and decreased DBP (coefficient = −0.014 mmHg per g, p = 0.026) (Fig. S3b), and a significant relationship between daily dose and DBP (coefficient = −0.3247 mmHg per g/day, p = 0.0182) (Fig. S4b).

Effects of taurine on FBG

Overall, taurine supplementation significantly reduced FBG levels compared to the control group (WMD: −5.882 mg/dL, 95% CI: −10.747 to −1.018, p = 0.018, I2 = 75.457) (Fig. 3). This effect remained consistent even after excluding individual studies in the sensitivity analysis (Fig. S5). Interestingly, meta-regression revealed a significant correlation between total dose and decreased FBG levels (coefficient = −0.495 mg/dL per g, p = 0.0011) (Fig. S6), but no significant relationship between daily dose and FBG (coefficient = −1.5146 mg/dL per g/day, p = 0.0703) (Fig. S7).

Fig. 3

Forest plot of overall effects of taurine on fasting blood glucose (FBG).

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Effects of taurine on TG

Taurine supplementation significantly reduced TG levels compared to the control group (WMD: −18.315 mg/dL, 95% CI: −25.628 to −11.002, p < 0.001, I2 = 35.539) (Fig. 4). This effect remained consistent even after excluding individual studies in a sensitivity analysis (Fig. S8). While meta-regression did not reveal a statistically significant dose-dependent relationship between total dose and TG reduction (coefficient = −0.0522 mg/dL per g, p = 0.0730) (Fig. S9), it revealed a significant relationship between daily dose and TG (coefficient = −3.3600 mg/dL per g/day, p = 0.0062) (Fig. S10).

Fig. 4

Forest plot of overall effects of taurine on triglyceride (TG).

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Effects of taurine on HDL-C

Overall, taurine supplementation did not significantly increase HDL-C levels compared to the control group (WMD: 0.644 mg/dL, 95% CI: −0.244 to 1.532, p = 0.155, I2 = 7.655) (Fig. 5). This observation remained consistent in the sensitivity analysis (Fig. S11). Similarly, meta-regression did not show a statistically significant dose-dependent relationship between total dose and HDL-C levels (coefficient = 0.0037 mg/dL per g, p = 0.2729) (Fig. S12). Moreover, it didn’t reveal a significant relationship between daily dose and HDL-C (coefficient = 0.1370 mg/dL per g/day, p = 0.3200) (Fig. S13).

Fig. 5

Forest plot of overall effects of taurine on high density lipoprotein-cholesterol (HDL-C).

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Publication bias

Funnel plot analysis for all investigated outcomes (SBP, DBP, FBG, TG, and HDL-C) indicated no evidence of publication bias. The distribution effect sizes were symmetric, as confirmed by Egger’s regression test, with p values exceeding 0.5 for all outcomes (p = 0.439, p = 0.213, p = 0.083, p = 0.166, and p = 0.158, respectively) (Figs. S14–S17).

Secondary outcomesEffects of taurine on body composition

Taurine supplementation did not significantly impact BW or BMI compared to the control group. The pooled effect size for BW change was minimal and non-significant (WMD: −0.642 kg, 95% CI: −1.494 to 0.209, p = 0.139) (Fig. S18a). Similarly, the effect size for BMI change was not statistically significant (WMD: −0.296 kg, 95% CI: −0.889 to 0.296, p = 0.327) (Fig. S18b). These findings were further supported by a sensitivity analysis with consistent non-significant effects of taurine on both BW and BMI (Fig. S18c, d).

Effects of taurine on lipid profiles

Taurine demonstrated a significant beneficial effect on lipid profiles. Compared to the control group, taurine supplementation significantly reduced both TC and LDL-C levels. The pooled effect size showed a notable decrease in TC (WMD: −8.305 mg/dL, 95% CI: −13.771 to −2.929, p = 0.003) (Fig. S19a), and a similar statistically significant effect was observed for LDL-C levels (WMD: −6.495 mg/dL, 95% CI: −10.912 to −2.079, p = 0.004) (Fig. S19b). These findings were further validated by a sensitivity analysis showing consistent significant effects of taurine on both TC and LDL-C reduction (Fig. S19c and Fig. S19d).

Effects of taurine on glycemic status

Taurine supplementation positively impacted several glycemic markers. Pooled effect sizes revealed significant reductions in HbA1c (WMD: −0.341%, 95% CI: −0.709 to −0.028, p = 0.070) (Fig. S20a), HOMA index (WMD: −0.693, 95% CI: −1.133 to −0.252, p = 0.002) (Fig. S20b), and fasting insulin levels (WMD: −1.521 mU/L, 95% CI: −2.591 to −0.451, p = 0.005) (Fig. S20c) compared to the control group. A sensitivity analysis showed a consistently non-significant effect on HbA1c reduction (Fig. S20d) but maintained consistent significant effects on both HOMA and fasting insulin (Fig. S20e, f).

Adverse effects

Meta-analysis of the treatment-associated adverse effect rates showed no significant differences between the taurine and control groups (odds ratio = 1.481, 95% CI = 0.843–2.604, p = 0.172) (Fig. S17).

Discussion

Our meta-analysis found that taurine supplementation significantly reduced SBP, DBP, FBG, and TG levels, suggesting an improvement in risk factors associated with MetS. A dose-dependent effect is evident on SBP, DBP, FBG, and TG levels, as influenced by both dose per day and total dose. Even though not all parameters reached statistical significance, the consistent trends point to a higher physiological response to administered substance doses. However, our analysis revealed no discernible dose-dependent effect on HDL-C levels, irrespective of dose per day or total dose. Notably, taurine did not exhibit any apparent adverse effects.

Compared to the control group, taurine demonstrated a significant lowering of both SBP and DBP. The hypotensive effect may be attributed to several mechanisms, primarily through increased nitric oxide availability [15] and enhanced hydrogen sulfide production [14], ultimately leading to improved blood flow dilation [13]. Our findings also revealed a remarkable ability of taurine to effectively reduce FBG levels. This suggests a positive impact on glycemic control, potentially via various mechanisms. These include: reduced hepatic glucose production, inhibition of glucagon activity, elevated uncoupling protein 1 levels [40], enhanced insulin clearance by insulin-degrading enzymes [41], and support for the health of beta-pancreatic cells [42]. Furthermore, taurine may upregulate adiponectin mRNA expression‎ and increase blood adiponectin levels, thereby improving insulin sensitivity [43] and contributing to overall metabolic health.

A previous meta-analysis by Guan et al. [44] found no significant difference in FBG between taurine and control groups, our results revealed a notable reduction. This discrepancy may be due to our inclusion of more studies involving individuals with diabetes, where baseline glucose levels were already elevated [19, 26, 29, 32]. This suggests that taurine’s impact might be less pronounced in those with normal blood sugar regulation.

Taurine significantly reduced TG levels. This is likely due to its ability to enhance TG removal into the bile by stimulating the production of bile acid through heightened hepatic cholesterol 7α-hydroxylase activity. Additionally, taurine increases LDL-C receptor activity, aiding in LDL-C clearance from the blood [45].

While our meta-analysis did not show a statistically significant increase in HDL-C levels, the observed trends suggest potential benefits. HDL serves as a crucial form of endogenous lipid storage by removing excess cholesterol from peripheral tissues. Hepatocytes and intestinal cells are the main internal biosynthesisers that control its levels [46]. Taurine has known effects on promoting cholesterol catabolism, particularly by increasing CYP7A1 activity and bile acid synthesis, which enhances cholesterol removal through feces. Additionally, taurine decreases the expression‎ of ApoB-100 and ApoE, which are major receptors for LDL and VLDL, further aiding in cholesterol clearance [47]. It’s likely that taurine efficiently removes cholesterol, displacing the need for extra HDL clearance. Furthermore, although taurine has been shown to raise serum HDL levels in rats raised on a high-cholesterol diet [47], human trials usually do not include purposefully high-fat diets, and the majority of participants are not obese. Therefore, in contrast to animal research, the effects of taurine on HDL levels in human trials may be less apparent. It is noteworthy that these trends towards elevated HDL-C may have a noteworthy effect on lowering the atherosclerosis index, even in the absence of statistically significant results [48].

Beyond FBG, taurine demonstrates effectiveness in both glycemic control and lipid profiles, with significant reductions observed in TC, LDL-C, fasting insulin, and HOMA levels. Although our analysis revealed only marginal benefits on HbA1c (WMD -0.341 [95% CI: −0.709, −0.28], p = 0.07), this may be attributed to the limited duration and intensity of protocols in the included studies (dosages ranging from 3 to 168 g with tracking periods of eight weeks to three months). Conversely, a meta-analysis conducted by Tao et al. exclusively on patients with diabetes reported significant reductions in HbA1c levels (WMD −0.41 [95% CI: −0.74, −0.09], p = 0.01) [5]. All four of the included trials [26, 29, 32, 36] assessing HbA1c as an endpoint involved individuals with type 2 diabetes, indicating a lack of evidence regarding HbA1c level changes in participants with diabetes. The lack of studies conducted on populations without diabetes could be because these changes are unlikely in this population. Future research may delve deeper into this topic. Since HbA1c not only offers a trustworthy indicator of chronic hyperglycemia but also strongly correlates with the risk of long-term diabetes complications [49], more research is required to fully understand its impact on long-term glycemic control in larger populations.

Taurine did not appear to significantly affect BW or BMI. In the only trial demonstrating a decrease in body mass, Shari et al. [36] administered 1 g taurine daily for 3 months to participants with type 2 diabetes. However, findings from other trials consistently showed negligible effects on body mass within their respective protocols. This suggests that factors like hypocaloric diet and exercise likely have a greater impact on body weight in this context [8].

Taurine is classified as “generally considered as safe” by the United States Food and Drug Administration [50]. In line with this, our study did not reveal any significant differences in treatment-related adverse effects between the taurine and control groups. All reported events were mild and transient, involving primarily gastrointestinal issues, headaches, and fatigue. Notably, no instances of moderate or severe events were associated with taurine supplementation [19, 35, 38].

While previous studies have examined similar endpoints [5, 44], ours is the first to conduct a meta-regression analysis on dose-response relationships, highlighting the effectiveness of taurine in mitigating MetS risk factors in the general population. However, some limitations warrant further consideration.

The observed heterogeneity has the potential to attenuate the true effect of taurine, introducing variability across different populations that may result in diminished statistical significance for parameters such as TG and HDL-C. Several factors contribute to this heightened heterogeneity. Firstly, there is variation in the selection of participants across studies, where individuals with diabetes and obesity, although at high risk for metabolic diseases, may not necessarily be diagnosed with specific disorders. Secondly, inconsistencies in study protocols play a role, with some participants adhering to their regular diet and activity levels [8], while others follow calorie-modified plans [32], potentially influencing results and increasing heterogeneity. Thirdly, our included trials suggest that taurine is more effective in moderating metabolism among studies that exclusively recruit patients with obesity or diabetes, as their TG levels are inherently higher and more prone to decrease compared to those with cardiovascular disease or no definite metabolic disorder.

When examining the impact of taurine on lipid profiles in patients with cardiovascular disease, confounding factors such as concurrent medication use must be considered. Given that a large number of the included studies focus on patients with heart failure, it is important to remember that medications like diuretics, angiotensin-converting enzyme (ACE), and vasodilators, which are commonly prescribed for cardiovascular conditions, can affect lipid levels. Long-term use of ACE inhibitors like enalapril has shown to significantly reduce TC, TG, and Very Low-density lipoprotein (VLDL) in patients [51]. Thiazide-type diuretics, often used for hypertension, may increase TC and VLDL levels in the short term, while HDL-C levels remain unchanged [52].

The authors of some included trials [26, 29, 32] were more aware of the impact of lipid level resulting from concurrent medication use, and specifically instructed participants to maintain their standard therapeutic regimen, diet, and lifestyle, with careful monitoring and controlled for. To better understand taurine’s effects on lipid profiles, future clinical trials should carefully consider and possibly exclude patients using medications known to significantly impact lipid levels.

Direct data on waist circumference, another key MetS criterion, were unavailable for any of the included trials. Despite this, we incorporated BMI as a secondary outcome, which could indirectly reflect the potential impact of taurine on waist circumference due to their strong correlation [53].

Another critical issue is that the majority of included studies on taurine’s effects typically have short durations, lasting no more than two months, with only a few extending up to a year at most. This limited timeframe emphasizes the necessity for longer-term studies to validate taurine’s efficacy thoroughly. Future studies should conduct more future studies to ascertain the duration of taurine’s effects after its cessation. Such extended investigations are crucial to explore its potential incorporation into novel clinical guidelines for the management of MetS and related conditions.

토론

우리의 메타 분석에 따르면 타우린 보충제가

SBP, DBP, FBG, TG 수치를 현저하게 감소시켜,

대사증후군과 관련된 위험 요인의 개선을 시사합니다.

하루 복용량과 총 복용량에 따라

SBP, DBP, FBG, TG 수치에 대한 용량 의존적 효과가 분명하게 나타났습니다.

모든 매개변수가 통계적 유의성에 도달하지는 않았지만,

일관된 경향은 투여된 물질 용량에 대한 생리적 반응이 더 높음을 가리킵니다.

그러나, 우리의 분석 결과, 하루 복용량이나 총 복용량에 관계없이 HDL-C 수치에 대한 용량 의존적 효과가 뚜렷하게 나타나지 않았습니다. 특히, 타우린은 명백한 부작용이 나타나지 않았습니다.

대조군에 비해 타우린은 SBP와 DBP 모두에서 상당한 감소 효과를 나타냈습니다. 저혈압 효과는 주로 산화질소 가용성 증가[15]와 황화수소 생성 증가[14]를 통해 궁극적으로 혈류 팽창 개선[13]으로 이어지는 여러 가지 메커니즘에 기인할 수 있습니다. 또한, 타우린은 FBG 수치를 효과적으로 감소시키는 놀라운 능력을 가지고 있다는 사실도 밝혀졌습니다. 이는 다양한 메커니즘을 통해 잠재적으로 혈당 조절에 긍정적인 영향을 미칠 수 있음을 시사합니다. 그 중에는 간 포도당 생산 감소, 글루카곤 활동 억제, 결합해제단백질 1 수치 상승[40], 인슐린 분해효소에 의한 인슐린 제거율 증가[41], 베타 췌장 세포 건강 지원[42] 등이 있습니다. 또한, 타우린은 아디포넥틴 mRNA 발현을 증가시키고 혈액 내 아디포넥틴 수치를 증가시켜 인슐린 감수성을 향상시키고[43] 전반적인 대사 건강에 기여할 수 있습니다.

Guan et al. [44]의 이전 메타 분석에서는 타우린과 대조군 간의 FBG에 유의미한 차이가 발견되지 않았지만, 우리의 결과는 현저한 감소가 나타났습니다. 이러한 차이는 기준선 포도당 수치가 이미 상승한 당뇨병 환자를 대상으로 한 연구를 더 많이 포함했기 때문일 수 있습니다 [19, 26, 29, 32]. 이는 혈당 조절이 정상인 사람들에게 타우린의 영향이 덜 뚜렷할 수 있음을 시사합니다.

타우린은 TG 수치를 현저하게 감소시켰습니다. 이것은 간 콜레스테롤 7α-하이드록실라제의 활성을 증가시켜 담즙산 생성을 촉진함으로써 담즙으로의 TG 제거를 향상시키는 능력 때문인 것으로 보입니다. 또한, 타우린은 LDL-C 수용체 활동을 증가시켜 혈액에서 LDL-C 제거를 돕습니다 [45].

메타 분석 결과, HDL-C 수치가 통계적으로 유의미하게 증가하지는 않았지만, 관찰된 경향은 잠재적인 이점을 시사합니다. HDL은 말초 조직에서 과도한 콜레스테롤을 제거함으로써 내인성 지질 저장의 중요한 형태입니다. 간세포와 장 세포는 그 수치를 조절하는 주요 내부 생합성 세포입니다 [46].

타우린은 특히 CYP7A1 활성 및 담즙산 합성을 증가시켜 대변을 통한 콜레스테롤 제거를 촉진함으로써 콜레스테롤 이화 작용을 촉진하는 것으로 알려져 있습니다. 또한 타우린은 LDL과 VLDL의 주요 수용체인 ApoB-100과 ApoE의 발현을 감소시켜 콜레스테롤 제거를 더욱 촉진합니다 [47]. 타우린은 콜레스테롤을 효율적으로 제거하여 추가적인 HDL 제거의 필요성을 없애줍니다. 또한, 타우린이 콜레스테롤이 높은 식사를 한 쥐의 혈청 HDL 수치를 높인다는 사실이 밝혀졌지만[47], 인간 대상 실험에서는 고지방 식사를 의도적으로 포함하지 않으며, 참가자의 대부분은 비만이 아닙니다. 따라서 동물 실험과는 달리, 인간 대상 실험에서 타우린이 HDL 수치에 미치는 영향은 분명하지 않을 수 있습니다. 이러한 HDL-C 상승 경향이 통계적으로 유의미한 결과가 없더라도 동맥경화 지수를 낮추는 데 주목할 만한 영향을 미칠 수 있다는 점은 주목할 만합니다 [48].

타우린은 FBG 외에도 혈당 조절과 지질 프로필 모두에서 효과가 있으며, TC, LDL-C, 공복 인슐린, HOMA 수치에서 상당한 감소가 관찰되었습니다. 우리의 분석 결과 HbA1c에 대한 혜택이 미미한 것으로 나타났지만(WMD -0.341 [95% CI: -0.709, -0.28], p = 0.07), 이는 포함된 연구의 프로토콜 기간과 강도가 제한적이었기 때문일 수 있습니다(투여량은 3~168g, 추적 기간은 8주~3개월). 반대로, Tao 등이 당뇨병 환자만을 대상으로 실시한 메타 분석에서는 HbA1c 수치가 현저하게 감소한 것으로 나타났습니다(WMD −0.41 [95% CI: −0.74, −0.09], p = 0.01) [5]. HbA1c를 종점으로 평가하는 4개의 임상시험(26, 29, 32, 36) 모두 제2형 당뇨병 환자를 대상으로 진행되었기 때문에, 당뇨병 환자의 HbA1c 수치 변화에 관한 근거가 부족하다는 것을 의미합니다. 당뇨병이 없는 집단을 대상으로 한 연구가 부족한 이유는 이러한 집단에서 이러한 변화가 일어나지 않을 가능성이 높기 때문일 수 있습니다. 향후 연구에서는 이 주제에 대해 더 깊이 파고들 수 있을 것입니다. HbA1c는 만성 고혈당증의 신뢰할 수 있는 지표일 뿐 아니라 장기적인 당뇨 합병증의 위험과도 밀접한 관련이 있기 때문에[49], 더 많은 연구가 필요합니다. 더 많은 인구를 대상으로 HbA1c가 장기적인 혈당 조절에 미치는 영향을 완전히 이해하기 위해서 말입니다.

타우린은 체질량지수(BW)나 체질량지수(BMI)에 큰 영향을 미치지 않는 것으로 나타났습니다. 체질량 감소 효과를 입증한 유일한 실험에서, 샤리(Shari) 등은 제2형 당뇨병 환자들에게 3개월 동안 매일 1g의 타우린을 투여했습니다. 그러나 다른 실험의 결과들은 각 실험의 프로토콜 내에서 체질량에 미치는 영향이 미미하다는 것을 일관되게 보여줍니다. 이것은 저칼로리 식단과 운동과 같은 요인들이 이러한 맥락에서 체중에 더 큰 영향을 미칠 수 있음을 시사합니다 [8].

타우린은 미국 식품의약국(FDA)에 의해 “일반적으로 안전한 것으로 간주되는” 물질로 분류됩니다[50]. 이에 따라, 저희 연구에서는 타우린과 대조군 사이에 치료 관련 부작용에 있어 유의미한 차이가 발견되지 않았습니다. 보고된 모든 부작용은 경미하고 일시적이며, 주로 위장 문제, 두통, 피로와 관련된 것이었습니다. 특히, 타우린 보충제와 관련된 중등도 또는 중증의 부작용 사례는 발견되지 않았습니다[19, 35, 38].

이전 연구에서 유사한 종점(endpoint)을 조사한 바 있지만(5, 44), 저희의 연구는 용량-반응 관계에 대한 메타 회귀 분석을 수행한 최초의 연구로, 일반 인구 집단에서 메트포르민 내성 증후군(MetS) 위험 요인을 완화하는 타우린의 효과를 강조합니다. 그러나 몇 가지 제한 사항이 있으므로 추가적인 고려가 필요합니다.

관찰된 이질성은 타우린의 실제 효과를 약화시킬 수 있는 잠재력을 가지고 있으며, 다양한 집단에 걸쳐 변동성을 도입하여 TG 및 HDL-C와 같은 매개변수에 대한 통계적 유의성을 감소시킬 수 있습니다. 이러한 이질성 증가에는 여러 가지 요인이 기여합니다. 첫째, 연구 전반에 걸쳐 참가자 선택에 차이가 있습니다. 당뇨병과 비만이 있는 사람은 대사성 질환의 위험이 높지만, 반드시 특정 질환으로 진단되는 것은 아닙니다. 둘째, 연구 프로토콜의 불일치가 영향을 미칩니다. 일부 참가자는 평소 식습관과 활동 수준을 유지하는 반면[8], 다른 참가자는 칼로리 조절 식단을 따릅니다[32]. 이로 인해 결과에 영향을 미치고 이질성이 증가할 수 있습니다. 셋째, 저희가 포함시킨 임상시험에 따르면, 타우린은 비만이나 당뇨병 환자만을 대상으로 한 연구에서 신진대사를 조절하는 데 더 효과적입니다. 왜냐하면, 이들 환자의 트리글리세리드 수치가 본질적으로 더 높고, 심혈관 질환이 있거나 명확한 대사 장애가 없는 환자에 비해 감소하기 쉽기 때문입니다.

타우린이 심혈관 질환 환자의 지질 프로파일에 미치는 영향을 조사할 때, 병용 약물 사용과 같은 혼란 요인을 고려해야 합니다. 포함된 연구의 상당수가 심부전 환자를 대상으로 하고 있다는 점을 감안할 때, 이뇨제, 안지오텐신 전환 효소(ACE), 혈관 확장제와 같은 약물이 심혈관 질환에 일반적으로 처방되는 약물이며, 지질 수치에 영향을 미칠 수 있다는 점을 기억하는 것이 중요합니다. 에날라프릴과 같은 ACE 억제제를 장기간 사용하면 환자의 TC, TG, VLDL(Very Low-density lipoprotein)이 현저하게 감소하는 것으로 나타났습니다 [51]. 고혈압 치료에 흔히 사용되는 티아지드계 이뇨제는 단기적으로 TC와 VLDL 수치를 증가시킬 수 있지만, HDL-C 수치는 변하지 않습니다 [52].

포함된 일부 임상시험의 저자들은 [26, 29, 32] 병용 약물 사용으로 인한 지질 수치에 미치는 영향을 더 잘 알고 있었고, 특히 참가자들에게 표준 치료 요법, 식이요법, 생활 방식을 유지하고 주의 깊게 모니터링하고 통제하도록 지시했습니다. 타우린이 지질 프로파일에 미치는 영향을 더 잘 이해하기 위해 향후 임상시험에서는 지질 수치에 상당한 영향을 미치는 것으로 알려진 약물을 사용하는 환자를 신중하게 고려하고 가능하면 제외해야 합니다.

MetS의 또 다른 핵심 기준인 허리둘레에 대한 직접적인 데이터는 포함된 어떤 임상시험에서도 구할 수 없었습니다. 그럼에도 불구하고, 우리는 BMI를 2차 결과로 포함시켰는데, 이는 타우린이 허리둘레에 미치는 잠재적인 영향을 간접적으로 반영할 수 있기 때문입니다[53].

또 다른 중요한 문제는 타우린의 효과에 대한 대부분의 연구가 일반적으로 2개월 이하의 짧은 기간 동안만 진행되고, 최대 1년까지 진행되는 연구는 극소수에 불과하다는 점입니다. 이 제한된 기간은 타우린의 효능을 철저히 검증하기 위한 장기 연구의 필요성을 강조합니다. 향후 연구에서는 타우린 섭취 중단 후에도 그 효과가 지속되는 기간을 확인하기 위해 더 많은 연구를 수행해야 합니다. 이러한 확장된 조사는 대사증후군 및 관련 질환 관리를 위한 새로운 임상 지침에 타우린을 포함시킬 가능성을 탐구하는 데 매우 중요합니다.

Conclusion

In conclusion, our meta-analysis of RCTs highlights taurine supplementation’s significant potential in mitigating key MetS risk factors, including reductions in SBP, DBP, FBG, and TG levels. This underscores its potential as a complementary therapeutic agent for MetS management, offering a multifaceted approach to glycemic control and cardiovascular health. Future clinical trials should focus on determining optimal taurine dosage and treatment duration, especially in MetS-susceptible populations. Addressing limitations in existing trials, such as variations in dosage, trial duration, sample size, disease severity, and participant characteristics, is crucial for generating robust evidence. As taurine is an inexpensive and easily obtainable supplement, further research can fill knowledge gaps, supporting clinical guidelines on its use as a nutraceutical for MetS prevention and management. Integrating taurine supplementation with established pharmacological interventions may enhance treatment outcomes and overall cardiovascular health in MetS patients.

결론
결론적으로, 우리의 RCT 메타 분석은 타우린 보충제가 SBP, DBP, FBG, TG 수치 감소를 포함하여 주요 MetS 위험 요소를 완화하는 데 상당한 잠재력을 가지고 있음을 강조합니다. 이것은 MetS 관리를 위한 보완적 치료제로서의 잠재력을 강조하며, 혈당 조절과 심혈관 건강에 대한 다각적인 접근 방식을 제공합니다. 향후 임상 시험은 특히 MetS에 취약한 집단에서 최적의 타우린 투여량과 치료 기간을 결정하는 데 초점을 맞춰야 합니다. 복용량, 시험 기간, 표본 크기, 질병의 심각도, 참가자 특성 등의 기존 시험의 한계점을 해결하는 것은 강력한 증거를 생성하는 데 매우 중요합니다. 타우린은 저렴하고 쉽게 구할 수 있는 보충제이기 때문에 추가 연구를 통해 지식 격차를 메울 수 있으며, 대사증후군 예방 및 관리를 위한 기능성 식품으로서의 사용에 대한 임상 지침을 뒷받침할 수 있습니다. 타우린 보충제를 기존의 약리학적 중재와 통합하면 대사증후군 환자의 치료 결과와 전반적인 심혈관 건강을 향상시킬 수 있습니다.

Data availability

All data included in this study are shown in this article or supplementary information, any further request is available by contacting the corresponding authors.

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