Challenges and trends

尽管多酚干预改善了肠道微生物和心血管疾病的相关指标，但是总结这篇综述的结论时存在一些问题。首先，由于研究人群的差异，导致异质性存在。此外，这些研究中使用的多酚的异质性可能会导致肠道微生物调节的变化，从而影响健康益处或临床指标。还要注意的是，本综述中讨论的只有一种多酚是纯化合物，其余16  种是含多酚的食物/食品配料/配方提取物。因此，干预中膳食纤维的存在可能是调节肠道菌群的一个促成因素，或者更确切地说可能是益生元本身。至于研究转基因的方法，大多数随机对照试验都采用靶向法评估肠道菌群的变化，因此有可能遗漏非靶向人群。用于分析肠道微生物的不同分子生物学技术（FISH、FISH-FC、qPCR、DGGE、IS分析、16s rRNA测序）在分类水平上有很大的差异。尽管有8 项研究调查了与心血管疾病相关的指标，但各研究之间分析的指标却有所不同。由于上述限制，无法进行荟萃分析。

据我们所知，这是首次对多酚干预措施在改善肠道菌群和各种临床指标方面的有效性进行了系统综述。

Conclusion

总而言之，本综述支持多酚作为能够调节肠道微生物的益生元的概念，进而影响主要与心血管疾病相关的指标。除了双歧杆菌和乳杆菌外，多酚还可以积极调节其他肠道微生物，这些肠道微生物可以改善人类健康。然而，由于本综述所涉及研究的内部质量各异，因此有必要通过更大样本、更长的持续时间和高通量分子技术进行进一步结构合理的试验，以获得更具决定性的结果。

Prebiotic potential of polyphenols, its effect on gut microbiota and anthropometric/clinical markers: A systematic review of randomised controlled trials

Mohanambal Moorthy^a,e, Nathorn Chaiyakunapruk^b,c, Sabrina Anne Jacob^b,d,Uma D. Palanisamy^a,e,∗

^{a  JeffreyCheahSchoolofMedicineandHealthSciences,MonashUniversityMalaysia,JalanLagoonSelatan,47500,BandarSunway,Selangor,Malaysia}

^{b  SchoolofPharmacy,MonashUniversityMalaysia,JalanLagoonSelatan,47500,BandarSunway,Selangor,Malaysia}

^{c  DepartmentofPharmacotherapy,CollegeofPharmacy,UniversityofUtah,SaltLakeCity,UT,USA}

^{d  StrathclydeInstituteofPharmacy&BiomedicalSciences,UniversityofStrathclyde,161CathedralSt,Glasgow,G40RE,Scotland,UK}

^{e  TropicalMedicineandBiologyPlatform,SchoolofScience,MonashUniversityMalaysia,JalanLagoonSelatan,47500BandarSunway,Selangor,Malaysia}

Abstract

Background:  

Polyphenols have been implicated to have numerous health benefits, and much of these are attributed to the metabolism of phenolic compounds by gut microbiota. The aim of this systematic review was to examine the effects of polyphenol consumption in modulating gut microbiota and anthropometric variables/clinical markers in randomised controlled trials (RCTs).

Scope and approach:

We systematically searched PubMed, Scopus, Embase, Cochrane library and Web of Science databases from inception to31^st  July 2019 following the PRIMSA guidelines.RCTs reporting on the effects of polyphenol consumption on gut microbes, and anthropometric variables (body weight, BMI, waist circumference, hip circumference)/clinical markers (CVD markers, and colon cancer markers) were included in this review. The methodological quality of the studies was assessed using the Cochrane Collaboration's risk of bias tool and Jadad scale.

Key findings and conclusion:

Seventeen RCTs met the inclusion criteria. Ten studies highlighted significant changes in the microbial profile, while 15 reported significant changes in CVD and colon cancer markers. The univariate correlation data showed a significant correlation between certain genera with clinical markers, specifically TNFα, cholesterol, HDL, CRP, and LPS. In the multivariate analysis, negative correlations were reported betweenLactobacillus  and TAG, CRP,  Bacteroides  with TAG, HDL, DBP, and SBP, andBifidobacterium  with cholesterol and CRP. This review supports the notion of polyphenols as prebiotics as significant modulation of intestinal microbes affecting mainly CVD markers were found in most of the RCTs. Further well-structured trials with larger sample size, longer duration, and high-throughput molecular techniques, will provide more conclusive results.