Determining the structural- and functional-level effects of diet-specific interventions on the gut microbiota of a diverse sample of Southern United States adults

在黑人和白人中，结直肠癌(CRC)发病率的种族差异仍然存在。鉴于之前的 我们团队的工作记录了黑人和白人肠道微生物区系的种族差异和证据 支持饮食和肠道微生物群之间的相互作用是结直肠癌的风险因素，这项研究 不同的饮食如何影响不同种族的肠道微生物区系的结构和功能是合理的。 之前的研究表明，肠道微生物区系可以随着饮食的变化而迅速改变。例如, 摄入极高纤维(50克)的饮食已经引起肠道微生物区系的变化，这些变化是 据信可以降低患癌症的风险。停止高血压的饮食方法(DASH)饮食，富含水果， 蔬菜、全谷物和低脂乳制品通常被推荐对心脏健康，并已被证明 降低血压，减轻体重。然而，据我们所知，DASH饮食对健康的影响 肠道微生物区系尚未被研究过。因为DASH饮食提供了大量的纤维，我们假设 食用DASH饮食将改善非西班牙裔黑人和白人的肠道微生物区系 成年人。在这个提案中，我们计划通过招募一个总体健康的112人样本来检验我们的假设 来自阿拉巴马州伯明翰的黑人和白人成年人参加了一项为期28天的随机对照喂养研究。 参与者将被随机接受DASH饮食或标准美国饮食。所有的餐点都是 由这项研究提供。在饮食前、中、后的多个时间点采集粪便样本。 干预，并将用聚合酶链式反应分析扩增16S rRNA基因的V4区并测序 使用MiSeq平台的基本功能。排序后的数据将使用QIIME进行分析。我们假设 接受DASH饮食的参与者将有更大的阿尔法多样性增加和更大的变化 与接受标准美国饮食的参与者相比，结直肠癌相关微生物的丰度更高。我们还将 评估功能水平的标志物，包括胆汁酸和短链脂肪酸(SCFA)的产生和 炎性标记物。如果我们的假设得到支持，我们预计次级胆汁的产量将会减少。 酸(例如脱氧胆酸)，更多的SCFA产生(例如丁酸盐)，以及肠道和全身的减少 与标准饮食相比，接受DASH饮食的参与者中的炎症(例如，钙保护素、IL-6) 美式饮食。我们的发现将为DASH饮食作为一种培养方法提供初步证据 不同种族人群之间更健康的肠道微生物区系。这些发现可能会影响临床、翻译、 以及调整肠道微生物区系以降低慢性病风险的人口水平方法，如 CRC。

Racial disparities in colorectal cancer (CRC) incidence persist for blacks and whites. Given the previous work of our team documenting racial differences in the gut microbiota of blacks and whites and the evidence supporting the interaction between diet and the gut microbiota as a risk factor for colorectal cancer, the study of how various diets affect the structure and function of the gut microbiota across racial groups is warranted. Previous research has shown that the gut microbiota can be rapidly altered by changes in diet. For example, consumption of an extremely high fiber (>50 grams) diet has produced changes in the gut microbiota that are believed to reduce cancer risk. The Dietary Approaches to Stop Hypertension (DASH) diet, rich in fruits, vegetables, whole grains and low-fat dairy, is commonly recommended for heart health and has been shown to lower blood pressure and produce weight loss. However, to our knowledge, the effect of the DASH diet on the gut microbiota has not been studied. Because the DASH diet provides substantial fiber, we hypothesize that consumption of the DASH diet will lead to improvements in the gut microbiota of non-Hispanic black and white adults. In this proposal, we plan to investigate our hypothesis by recruiting a generally healthy sample of 112 black and white adults from Birmingham, AL to participate in a 28-day randomized, controlled feeding study. Participants will be randomized to receive either the DASH diet or a standard American diet. All meals will be provided by the study. Fecal samples will be collected at multiple time points before, during, and after the dietary intervention and will be analyzed using PCR to amplify the V4 region of the 16S rRNA gene and to sequence bases using the MiSeq platform. Sequenced data will then be analyzed using QIIME. We hypothesize that participants receiving the DASH diet will have a greater increase in alpha diversity and greater changes in abundances of CRC-associated microbes than participants receiving the standard American diet. We will also evaluate functional-level markers including bile acid and short chain fatty acid (SCFA) production and inflammatory markers. If our hypothesis is supported, we expect to see reduced production of secondary bile acids (e.g., deoxycholic acid), greater SCFA production (e.g, butyrate), and reduction in gut and systemic inflammation (e.g, calprotectin, IL-6) among participants receiving the DASH diet compared to the standard American diet. Our findings will provide preliminary evidence for the DASH diet as an approach for cultivating a healthier gut microbiota across racially diverse populations. These findings can impact clinical, translational, and population-level approaches for modification of the gut microbiota to reduce risk of chronic diseases like CRC.