论文标题：Role of whole grains versus fruits and vegetables in reducing subclinical inflammation and promoting gastrointestinal health in individuals affected by overweight and obesity: a randomized controlled trial

期刊：

作者：Julianne C. Kopf, Mallory J. Suhr, Jennifer Clarke, Seong-il Eyun, Jean-Jack M. Riethoven, Amanda E. Ramer-Tait and Devin J. Rose

发表时间：2018/07/30

数字识别码：10.1186/s12937-018-0381-7

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全谷物（whole grains，WG）以及水果和蔬菜（fruits and vegetables，FV）已经被证明可以通过调节肠道微生物群来降低代谢疾病的风险。

近期发表在BMC旗下Nutrition Journal上的一篇文章研究了增加WG或FV的摄入对炎症标志物和肠道微生物群组成的影响，以及这些饮食方式对受超重和肥胖困扰的个体的影响。

在美国，不良的饮食习惯已经成为过早死亡和残疾的主要威胁因素。不良的饮食习惯会导致代谢综合征及其相关疾病，如分别在常见死亡原因中排名第一和第七的心脏病和糖尿病等。治疗这些慢性病的医疗费用每年超过6000亿美元。因此，美国政府已经采取了相当大的政策调整来使社会更健康，尤其是使得居民的饮食更健康。

有许多人体试食试验显示，食用水果和蔬菜（FV）或全谷物（WG）会对代谢综合征的标志物产生重大影响。在典型的2000千卡饮食中，美国农业部目前的建议是每天消耗5份FV和3份WG。不幸的是，FV和WG摄入量通常远低于推荐值。在2015年的手机版中，76％的美国人口没有达到推荐的水果摄入量，87％的人口没有达到推荐的蔬菜摄入量。

人们认为WG和FV对新陈代谢有益，一部分考量是认为它们与肠道微生物群之间存在相互作用。肠道微生物群可以介导WG和FV的抗炎作用，其中一种途径是通过促进短链脂肪酸（short chain fatty acid，SCFA）的产生，而SCFA是膳食纤维发酵的主要代谢终产物。已知这些酸在上皮细胞正常功能的维持上具有一定的营养作用，并且在血液中通过循环对远端部位输送营养。例如：SCFA通过增加粘蛋白的产生，抑制肠道病原体的生长，并且增加营养的吸收来帮助维持肠道的正常屏障功能。在远端部位，SCFA是碳水化合物和脂质代谢的信号分子。还有研究认为，SCFA合成的增加也与癌症和肥胖风险的降低有关。

为了验证WG与FV饮食在减轻亚临床炎症和促进受超重和肥胖影响的个体的胃肠健康方面的作用，来自美国内布拉斯加大学林肯分校的研究人员对49名超重或肥胖且FV和WG摄入量低的受试者进行了随机平行人体试食试验。（试验注册：ClinicalTrials.gov，NCT02602496，Nov 4, 2017）将个体随机分成三组：WG，FV和对照（精制谷物）。在研究开始时和6周后收集粪便和血液样品。测量炎症标志物[肿瘤坏死因子-α（TNF-α），白细胞介素-6（IL-6），脂多糖结合蛋白（LBP）和高敏C-反应蛋白（hs-CRP）]。对粪便样品进行了短/支链脂肪酸（S / BCFA）和微生物群成分的分析。

图2. 在试验期间炎症标志物的变化情况

研究发现，对于WG（ - 0.2μg/ mL，p = 0.02）和FV（ - 0.2μg/ mL，p = 0.005）饮食的参与者，LBP显着降低，对照饮食（0.1μg）没有变化/ mL，p = 0.08）。FV饮食诱导IL-6显着变化（ - 1.5 pg / mL，p = 0.006），但其他处理没有观察到显着变化（对照， - 0.009 pg / mL，p = 0.99; WG， - 0.29 ，p = 0.68）。WG饮食导致TNF-α显着降低（ - 3.7 pg / mL; p <0.001），而对其他处理没有显着影响（对照组， - 0.6 pg / mL，p = 0.6; FV ， - 1.4 pg / mL，p = 0.2）（图2）。

图3. 治疗期间粪便微生物的变化

这些处理引起微生物组成的个体化变化，除了FV组中α-多样性的显著增加外，没有发现治疗组的差异（图3）。

图4. 研究期间血浆标志物变化与微生物组成的关系

与基线微生物群组成相比，研究期间炎症标志物的变化与研究期间或研究结束时的微生物群组成变化更相关（图4）。并且，基础微生物群组成与LBP变化之间有显著的相关性（D）。

这些结果表明，FV和WG的干预显着且独特地减少了炎症的生物标志物。FV处理降低了循环IL-6和LBP，而WG处理降低了TNF-α和LBP。两种处理都对肠道微生物群具有个体化影响，并且FV处理中的α-多样性显着增加。这些数据支持WG和FV的摄入对受超重或肥胖影响的个体的代谢健康的正面作用。

摘要：

Background

Whole grains (WG) and fruits and vegetables (FV) have been shown to reduce the risk of metabolic disease, possibly via modulation of the gut microbiota. The purpose of this study was to determine the impact of increasing intake of either WG or FV on inflammatory markers and gut microbiota composition.

Methods

A randomized parallel arm feeding trial was completed on forty-nine subjects with overweight or obesity and low intakes of FV and WG. Individuals were randomized into three groups (3 servings/d provided): WG, FV, and a control (refined grains). Stool and blood samples were collected at the beginning of the study and after 6 weeks. Inflammatory markers [tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), lipopolysaccharide binding protein (LBP), and high sensitivity C-reactive protein (hs-CRP)] were measured. Stool sample analysis included short/branched chain fatty acids (S/BCFA) and microbiota composition.

Results

There was a significant decrease in LBP for participants on the WG (− 0.2 μg/mL, p = 0.02) and FV (− 0.2 μg/mL, p = 0.005) diets, with no change in those on the control diet (0.1 μg/mL, p = 0.08). The FV diet induced a significant change in IL-6 (− 1.5 pg/mL,p = 0.006), but no significant change was observed for the other treatments (control, − 0.009 pg/mL, p = 0.99; WG, − 0.29, p = 0.68). The WG diet resulted in a significant decrease in TNF-α (− 3.7 pg/mL; p < 0.001), whereas no significant effects were found for those on the other diets (control, − 0.6 pg/mL, p = 0.6; FV, − 1.4 pg/mL, p = 0.2). The treatments induced individualized changes in microbiota composition such that treatment group differences were not identified, except for a significant increase in α-diversity in the FV group. The proportions of Clostridiales (Firmicutes phylum) at baseline were correlated with the magnitude of change in LBP during the study.

Conclusions

These data demonstrate that WG and FV intake can have positive effects on metabolic health; however, different markers of inflammation were reduced on each diet suggesting that the anti-inflammatory effects were facilitated via different mechanisms. The anti-inflammatory effects were not related to changes in gut microbiota composition during the intervention, but were correlated with microbiota composition at baseline.

Trial registration

ClinicalTrials.gov, NCT02602496, Nov 4, 2017.

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期刊介绍:

Nutrition Journal (, 3.568 - , 4.198 - ) publishes novel surveillance, epidemiologic, and intervention research that sheds light on i) influences (e.g., familial, environmental) on eating patterns; ii) associations between eating patterns and health, and iii) strategies to improve eating patterns among populations. The journal also welcomes manuscripts reporting on the psychometric properties (e.g., validity, reliability) and feasibility of methods (e.g., for assessing dietary intake) for human nutrition research. In addition, study protocols for controlled trials and cohort studies, with an emphasis on methods for assessing dietary exposures and outcomes as well as intervention components, will be considered.

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