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Dietary nutrients are associated with the development of cardiovascular disease (CVD) both through traditional pathways (inducing hyperlipidemia and chronic inflammation) and through the emergence of a metaorganism-pathogenesis pathway (through the gut microbiota, its metabolites, and host). Several molecules from food play an important role as CVD risk-factor precursors either themselves or through the metabolism of the gut microbiome. Animal-based dietary proteins are the primary source of CVD risk-factor precursors; however, some plants also possess these precursors, though at relatively low levels compared with animal-source food products. Various medications have been developed to treat CVD through the gut-microbiota–circulation axis, and they exhibit potent effects in CVD treatment. Nevertheless, such medicines are still being improved, and there are many research gaps that need to be addressed. Furthermore, some medications have unpleasant or adverse effects. Numerous foods and herbs impart beneficial effects upon health and disease. In the past decade, many studies have focused on treating and preventing CVD by modulating the gut microbiota and their metabolites. This review provides an overview of the available information, summarizes current research related to the gut-microbiota–heart axis, enumerates the foods and herbs that are CVD-risk precursors, and illustrates how metabolites become CVD risk factors through the metabolism of gut microbiota. Moreover, we present perspectives on the application of foods and herbs—including prebiotics, probiotics, synbiotics, postbiotics, and antibiotic-like substances—as CVD prevention agents to modulate gut microbiota by inhibiting gut-derived CVD risk factors. Taxonomy (classification by EVISE): Cardiovascular disease, gut microbiota, herbal medicine, preventive medicine, dietary therapy, nutrition supplements.

Background/purpose: Appropriate storage of fecal samples is a critical step for the unbiased analysis of microbial communities in metagenomic studies. Rapid freezing at −80 °C is usually considered to be best practice, but this approach is challenging. DNA stabilizing kits may provide a more convenient method to preserve and store clinical samples. We evaluated the reliability of two collection kits (Stratec stool collection tube with stabilizer, #1038111200 and OMNIgene.GUT OMR-200) on preserving fecal microbiota. Methods: Samples were collected from two locations of the fecal specimen, in four healthy volunteers. The samples were sub-aliquoted and stored in a −80 °C freezer, in Stratec and OMNIgene.GUT (incubation at ambient temperature for 0, 3, or 7 days). The fecal microbial composition was assessed by 16S rRNA sequencing. Results: We found that alpha diversity was not significantly affected by storage conditions. Samples stored in DNA stabilizers were still representative of the original microbial community after 7 days at ambient temperature. Individual differences were found to have a greater contribution to the differences in microbial community composition than storage conditions or sampling location. Samples subjected to stabilizers displayed microbial community shifts compared with immediately frozen samples. A linear discriminant analysis effect size (LEfSe) analysis showed that the relative abundances of Faecalibacterium were significantly higher in samples stored in Stratec kits. Conclusion: Our study reveals that both Stratec and OMNIgene.GUT kits provide good microbiome preservation for up to 7 days in ambient temperature and would represent good options for fecal sample collection in large scale, population-based studies.

Although great interest has been displayed by researchers in the contribution of gut microbiota to human health, there is still no standard protocol with consensus to guarantee the sample quality of metagenomic analysis. Here we reviewed existing methodology studies and present suggestions for optimizing research pipeline from fecal sample collection to DNA extraction. First, we discuss strategies of clinical metadata collection as common confounders for microbiome research. Second, we propose general principles for freshly collected fecal sample and its storage and share a DIY stool collection kit protocol based on the manual procedure of Human Microbiome Project (HMP). Third, we provide a useful information of collection kit with DNA stabilization buffers and compare their pros and cons for multi-omic study. Fourth, we offer technical strategies as well as information of novel tools for sample aliquoting before long-term storage. Fifth, we discuss the substantial impact of different DNA extraction protocols on technical variations of metagenomic analysis. And lastly, we point out the limitation of current methods and the unmet needs for better quality control of metagenomic analysis. We hope the information provided here will help investigators in this exciting field to advance their studies while avoiding experimental artifacts. Keywords: Gut microbiome, Stool collection, Sample processing, Storage condition, Standardization

Trimethylamine N-oxide (TMAO) was recently discovered as a novel and independent risk factor for promoting atherosclerosis while it has been found to be generated from dietary carnitine through metabolism of gut microbiota for decades. Antibiotics were found to successfully inhibit the pathway of gut microbiota-dependent TMAO formation, as well as prevention of atherosclerosis. However, the side effects and resistance potential of antibiotics limit their potential application. Allicin is a well-established antimicrobial phytochemical naturally found in fresh blended garlic and easily acquired from diet. Here we demonstrated that the plasma TMAO levels in C57BL/6 mice fed with dietary carnitine were 4–22 times greater than that in the control chow diet group during carnitine challenge test. Interestingly, the differences of plasma TMAO level were not seen when comparing mice in carnitine plus allicin diet group with the control chow diet group. The results of this study suggest that dietary allicin may be capable of protecting the host from producing TMAO when carnitine is consumed through its impact on gut microbiota. Allicin and dietary fresh garlic containing allicin may be used as functional foods for the prevention of atherosclerosis.