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

结直肠癌（CRC）发病率的种族差异在黑人和白人中持续存在。鉴于此前 我们团队的工作记录了黑人和白人肠道微生物群的种族差异， 支持饮食和肠道微生物群之间的相互作用作为结直肠癌的风险因素， 不同的饮食如何影响不同种族群体的肠道微生物群的结构和功能是有必要的。 以前的研究表明，肠道微生物群可以通过饮食的变化迅速改变。比如说， 摄入极高纤维（>50克）的饮食会导致肠道微生物群发生变化， 被认为可以降低癌症风险。停止高血压的饮食方法（DASH）饮食，富含水果， 蔬菜、全谷物和低脂奶制品通常被推荐用于心脏健康， 降低血压并减轻体重。然而，据我们所知，DASH饮食对 肠道微生物群尚未被研究。因为DASH饮食提供了大量的纤维，我们假设， DASH饮食的消费将导致非西班牙裔黑人和白色人的肠道微生物群的改善 成年人了在这个提议中，我们计划通过招募112名健康的样本来调查我们的假设。 来自阿拉巴马州伯明翰的黑人和白色成年人参加一项为期28天的随机对照喂养研究。 参与者将随机接受DASH饮食或标准美国饮食。所有的食物都将 研究提供的。将在饮食前、饮食中和饮食后的多个时间点采集粪便样本。 干预，并将使用PCR进行分析，以扩增16S rRNA基因的V4区域并进行测序。 使用MiSeq平台。然后使用QIIME分析测序数据。我们假设 接受DASH饮食的参与者将有更大的α多样性增加和更大的变化， CRC相关微生物的丰度高于接受标准美国饮食的参与者。我们还将 评估功能水平标志物，包括胆汁酸和短链脂肪酸（SCFA）的产生， 炎症标志物。如果我们的假设得到支持，我们预计会看到次级胆汁的产生减少 酸（例如，脱氧胆酸），更大的SCFA产生（例如，丁酸盐），以及肠道和全身 接受DASH饮食的参与者与接受标准DASH饮食的参与者相比， 美国饮食我们的研究结果将为DASH饮食作为培养 更健康的肠道微生物群。这些发现可能会影响临床，翻译， 和人群水平的方法来改变肠道微生物群，以降低慢性疾病的风险， 《儿童权利公约》。

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.