Dietary allicin reduces transformation of L-carnitine to TMAO through impact on gut microbiota

Therapeutic potential of lipid-lowering probiotics on the atherosclerosis development

Hypercholesterolemia is a critical risk factor for atherosclerosis, mostly attributed to lifestyle behavior such as diet. Recent advances have emphasized the critical effects of gastrointestinal bacteria in the pathology of hypercholesterolemia and atherosclerosis, suggesting that the gastrointestinal microbiome can therefore provide efficient therapeutic targets for preventing and treating atherosclerosis. Thus, interventions, such as probiotic therapy, aimed at altering the bacterial composition introduce a promising therapeutic procedure. In the current review, we will provide an overview of anti-atherogenic probiotics contributing to lipid-lowering, inhibiting atherosclerotic inflammation, and suppressing bacterial atherogenic metabolites.

The Effects of Food Nutrients and Bioactive Compounds on the Gut Microbiota: A Comprehensive Review

It is now widely recognized that gut microbiota plays a critical role not only in the development and progression of diseases, but also in its susceptibility to dietary patterns, food composition, and nutritional intake. In this comprehensive review, we have compiled the latest findings on the effects of food nutrients and bioactive compounds on the gut microbiota. The research indicates that certain components, such as unsaturated fatty acids, dietary fiber, and protein have a significant impact on the composition of bile salts and short-chain fatty acids through catabolic processes, thereby influencing the gut microbiota. Additionally, these compounds also have an effect on the ratio of Firmicutes to Bacteroides, as well as the abundance of specific species like Akkermansia muciniphila. The gut microbiota has been found to play a role in altering the absorption and metabolism of nutrients, bioactive compounds, and drugs, adding another layer of complexity to the interaction between food and gut microbiota, which often requires long-term adaptation to yield substantial outcomes. In conclusion, understanding the relationship between food compounds and gut microbiota can offer valuable insights into the potential therapeutic applications of food and dietary interventions in various diseases and health conditions.

Cardiovascular risk of dietary trimethylamine oxide precursors and the therapeutic potential of resveratrol and its derivatives

Overall diet, lifestyle choices, genetic predisposition, and other underlying health conditions may contribute to higher trimethylamine N-oxide (TMAO) levels and increased cardiovascular risk. This review explores the potential therapeutic ability of RSV to protect against cardiovascular diseases (CVD) and affect TMAO levels. This review considers recent studies on the association of TMAO with CVD. It also examines the sources, mechanisms, and metabolism of TMAO along with TMAO-induced cardiovascular events. Plant polyphenolic compounds, including resveratrol (RSV), and their cardioprotective mechanism of regulating TMAO levels and modifying gut microbiota are also discussed here. RSV's salient features and bioactive properties in reducing CVD have been evaluated. The close relationship between TMAO and CVD is clearly understood from currently available data, making it a potent biomarker for CVD. Precise investigation, including clinical trials, must be performed to understand RSV's mechanism, dose, effects, and derivatives as a cardioprotectant agent.

Multi-nutrient interventions and cognitive ageing: are we barking up the right tree?

As we continue to elucidate the mechanisms underlying age-related brain diseases, the reductionist strategy in nutrition–brain function research has focused on establishing the impact of individual foods. However, the biological processes connecting diet and cognition are complex. Therefore, consideration of a combination of nutritional compounds may be most efficacious. One barrier to establishing the efficacy of multi-nutrient interventions is that the area lacks an established set of evidence-based guidelines for studying their effect on brain health. This review is an output of the International Life Sciences Institute (ILSI) Europe. A multi-disciplinary expert group was assembled with the aim of developing a set of considerations to guide research into the effects of multi-nutrient combinations on brain functions. Consensus recommendations converged on six key issues that should be considered to advance research in this area: (1) establish working mechanisms of the combination and contributions of each individual compound; (2) validate the relevance of the mechanisms for the targeted human condition; (3) include current nutrient status, intake or dietary pattern as inclusion/exclusion criteria in the study design; (4) select a participant population that is clinically and biologically appropriate for all nutritional components of the combination; (5) consider a range of cognitive outcomes; (6) consider the limits of reductionism and the ‘gold standard’ randomised controlled trial. These guiding principles will enhance our understanding of the interactive/complementary activities of dietary components, thereby strengthening the evidence base for recommendations aimed at delaying cognitive decline.

Importance of gut microbiota metabolites in the development of cardiovascular diseases (CVD)

Cardiovascular disease (CVD) remains the most common cause of death worldwide and has become a public health concern. The proven notable risk factors for CVD are atherosclerosis, hypertension, diabetes, dyslipidemia, inflammation, and some genetic defects. However, research has shown a correlation between metabolic health, gut microbiota, and dietary risk factors. The gut microbiota makes an important contribution to human functional metabolic pathways by contributing enzymes that are not encoded by the human genome, for instance, the breakdown of polysaccharides, polyphenols and vitamins synthesis. TMAO and SCFAs, human gut microbiota compounds, have respective immunomodulatory and pro-inflammatory effects. Choline and l-carnitine are abundant in high-fat diets and are transformed into TMA by gut bacteria. The liver's phase of metabolism then changes TMA into TMAO. In turn, TMAO promotes the activation of macrophages, damages vascular endothelium, and results in CVD-however, dysbiosis decreases SCFAs and bile acids, which raises intestinal permeability. Congestion in the portal vein, a drop in cardiac output, a reduction in intestinal perfusion, and intestinal leakage are all caused by heart failure. These factors induce systemic inflammation by increasing intestinal leakage. By raising CRP and pro-inflammatory reactions, human gut dysbiosis and elevated TMAO levels promote the development of arterial plaque, hasten the beginning of atherosclerosis, and raise the risk of CAD. A healthy symbiosis between the gut microbiota and host is a key factor in shaping the biochemical profile of the diet, therefore which are crucial for maintaining the intestinal epithelial barrier, growing mucosa, reducing inflammation, and controlling blood pressure.

G. Ranea J, Queipo-Ortuño MI, Plaza-Andrades I, Rodríguez-Capitán J, Pavón-Morón FJ, Jiménez-Navarro MF. Multi-Omics Approach Reveals Prebiotic and Potential Antioxidant Effects of Essential Oils from the Mediterranean Diet on Cardiometabolic Disorder Using Humanized Gnotobiotic Mice

Essential oils sourced from herbs commonly used in the Mediterranean diet have demonstrated advantageous attributes as nutraceuticals and prebiotics within a model of severe cardiometabolic disorder. The primary objective of this study was to assess the influences exerted by essential oils derived from thyme (Thymus vulgaris) and oregano (Origanum vulgare) via a comprehensive multi-omics approach within a gnotobiotic murine model featuring colonic microbiota acquired from patients diagnosed with coronary artery disease (CAD) and type-2 diabetes mellitus (T2DM). Our findings demonstrated prebiotic and potential antioxidant effects elicited by these essential oils. We observed a substantial increase in the relative abundance of the Lactobacillus genus in the gut microbiota, accompanied by higher levels of short-chain fatty acids and a reduction in trimethylamine N-oxide levels and protein oxidation in the plasma. Moreover, functional enrichment analysis of the cardiac tissue proteome unveiled an over-representation of pathways related to mitochondrial function, oxidative stress, and cardiac contraction. These findings provide compelling evidence of the prebiotic and antioxidant actions of thyme- and oregano-derived essential oils, which extend to cardiac function. These results encourage further investigation into the promising utility of essential oils derived from herbs commonly used in the Mediterranean diet as potential nutraceutical interventions for mitigating chronic diseases linked to CAD and T2DM.

Effects of dietary irritants on intestinal homeostasis and the intervention strategies

Abundant diet components are unexplored as vital factors in intestinal homeostasis. Dietary irritants stimulate the nervous system and provoke somatosensory responses, further inducing diarrhea, gut microbiota disorder, intestinal barrier damage or even severe gastrointestinal disease. We depicted the effects of food with piquancy, high fat, low pH, high-refined carbohydrates, and indigestible texture. The mechanism of dietary irritants on intestinal homeostasis were comprehensively summarized. Somatosensory responses to dietary irritants are palpable and have specific chemical and neural mechanisms. In contrast, even low-dose exposure to dietary irritants can involve multiple intestinal barriers. Their mechanisms in intestinal homeostasis are often overlapping and dose-dependent. Therefore, treating symptoms caused by dietary irritants requires personalized nutritional advice. The reprocessing of stimulant foods, additional supplementation with probiotics or prebiotics, and enhancement of the intestinal barrier are effective intervention strategies. This review provides promising preliminary guidelines for the treatment of symptoms and gastrointestinal injury caused by dietary irritants.

Microbiota-gut-brain axis impairment in the pathogenesis of stroke: implication as a potent therapeutic target

The human microbiota-gut-brain axis has an enormous role in the maintenance of homeostasis and health. Over the last two decades, it has received concerted research attention and focus due to a rapidly emerging volume of evidence that has established that impairment within the microbiota-gut-brain axis contributes to the development and progression of various diseases. Stroke is one of the entities identified to be associated with microbiota-gut-brain axis impairment. Currently, there are still limitations in the clinical treatment of stroke, and the presence of a non-nervous factor from gut microbiota that can alter the course of stroke presents a novel strategy towards the search for a therapeutic silver bullet against stroke. Hence, the aim herein, was to focus on the involvement of microbiota-gut-brain axis impairment in the pathogenesis stroke as well as elucidate its implications as a potent therapeutic target against stroke. The findings of studies to date have revealed and extended the role microbiota-gut-brain axis impairment in the pathogenesis of stroke, and studies have identified from both clinical and pre-clinical perspectives targets within the microbiota-gut-brain axis and successfully modulated the outcome of stroke. It was concluded that the microbiota-gut-brain axis stands as potent target to salvage the neurons in the ischemic penumbra for the treatment of stroke. Assessment of the microbiota profile and its metabolites status holds enormous clinical potentials as a non-invasive indicator for the early diagnosis and prognosis of stroke.

Beneficial Effects of Essential Oils from the Mediterranean Diet on Gut Microbiota and Their Metabolites in Ischemic Heart Disease and Type-2 Diabetes Mellitus

Ischemic heart disease (IHD) and type-2 diabetes mellitus (T2DM) remain major health problems worldwide and commonly coexist in individuals. Gut microbial metabolites, such as trimethylamine N-oxide (TMAO) and short-chain fatty acids (SCFAs), have been linked to cardiovascular and metabolic diseases. Previous studies have reported dysbiosis in the gut microbiota of these patients and the prebiotic effects of some components of the Mediterranean diet. Essential oil emulsions of savory (Satureja hortensis), parsley (Petroselinum crispum) and rosemary (Rosmarinus officinalis) were assessed as nutraceuticals and prebiotics in IHD and T2DM. Humanized mice harboring gut microbiota derived from that of patients with IHD and T2DM were supplemented with L-carnitine and orally treated with essential oil emulsions for 40 days. We assessed the effects on gut microbiota composition and abundance, microbial metabolites and plasma markers of cardiovascular disease, inflammation and oxidative stress. Our results showed that essential oil emulsions in mice supplemented with L-carnitine have prebiotic effects on beneficial commensal bacteria, mainly Lactobacillus genus. There was a decrease in plasma TMAO and an increase in fecal SCFAs levels in mice treated with parsley and rosemary essential oils. Thrombomodulin levels were increased in mice treated with savory and parsley essential oils. While mice treated with parsley and rosemary essential oils showed a decrease in plasma cytokines (INFɣ, TNFα, IL-12p70 and IL-22); savory essential oil was associated with increased levels of chemokines (CXCL1, CCL2 and CCL11). Finally, there was a decrease in protein carbonyls and pentosidine according to the essential oil emulsion. These results suggest that changes in the gut microbiota induced by essential oils of parsley, savory and rosemary as prebiotics could differentially regulate cardiovascular and metabolic factors, which highlights the potential of these nutraceuticals for reducing IHD risk in patients affected by T2DM.

The effects of probiotic administration on patients with prediabetes: a meta-analysis and systematic review

BACKGROUND

This paper aimed to examine the effects of probiotics on eight factors in the prediabetic population by meta-analysis, namely, fasting blood glucose (FBG), glycated haemoglobin A1c (HbA1c), homeostatic model assessment of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), and the mechanisms of action are summarized from the existing studies.

METHODS

Seven databases (PubMed, Web of Science, Embase, Cochrane Library, SinoMed, CNKI, and Wanfang Med) were searched until March 2022. Review Manager 5.4 was used for meta-analysis. The data were analysed using weighted mean differences (WMDs) or standardized mean differences (SMDs) under a fixed effect model to observe the efficacy of probiotic supplementation on the included indicators.

RESULTS

Seven publications with a total of 460 patients were included. According to the meta-analysis, probiotics were able to significantly decrease the levels of HbA1c (WMD, -0.07; 95% CI -0.11, -0.03; P = 0.001), QUICKI (WMD, 0.01; 95% CI 0.00, 0.02; P = 0.04), TC (SMD, -0.28; 95% CI -0.53, -0.22; P = 0.03), TG (SMD, -0.26; 95% CI -0.52, -0.01; P = 0.04), and LDL-C (WMD, -8.94; 95% CI -14.91, -2.97; P = 0.003) compared to levels in the placebo group. The effects on FBG (WMD, -0.53; 95% CI -2.31, 1.25; P = 0.56), HOMA-IR (WMD, -0.21; 95% CI -0.45, 0.04; P = 0.10), and HDL-C (WMD, 2.05; 95% CI -0.28, 4.38; P = 0.08) were not different from those of the placebo group.

CONCLUSION

The present study clearly indicated that probiotics may fulfil an important role in the regulation of HbA1c, QUICKI, TC, TG and LDL-C in patients with prediabetes. In addition, based on existing studies, we concluded that probiotics may regulate blood glucose homeostasis in a variety of ways.

TRIAL REGISTRATION

This meta-analysis has been registered at PROSPERO with ID: CRD42022321995.

Two-component carnitine monooxygenase from Escherichia coli: Functional characterization, Inhibition and mutagenesis of the molecular interface

Gut microbial production of trimethylamine (TMA) from l-carnitine is directly linked to cardiovascular disease. TMA formation is facilitated by carnitine monooxygenase, which was proposed as a target for the development of new cardioprotective compounds. Therefore, the molecular understanding of the two-component Rieske-type enzyme from Escherichia coli was intended. The redox cofactors of the reductase YeaX (FMN, plant-type [2Fe-2S] cluster) and of the oxygenase YeaW (Rieske-type [2Fe-2S] and mononuclear [Fe] center) were identified. Compounds meldonium and the garlic-derived molecule allicin were recently shown to suppress microbiota-dependent TMA formation. Based on two independent carnitine monooxygenase activity assays, enzyme inhibition by meldonium or allicin was demonstrated. Subsequently, the molecular interplay of the reductase YeaX and the oxygenase YeaW was addressed. Chimeric carnitine monooxygenase activity was efficiently reconstituted by combining YeaX (or YeaW) with the orthologous oxygenase CntA (or reductase CntB) from Acinetobacter baumannii. Partial conservation of the reductase/oxygenase docking interface was concluded. A structure guided mutagenesis approach was used to further investigate the interaction and electron transfer between YeaX and YeaW. Based on AlphaFold structure predictions, a total of 28 site-directed variants of YeaX and YeaW were kinetically analyzed. Functional relevance of YeaX residues Arg²⁷¹, Lys³¹³ and Asp³²⁰ was concluded. Concerning YeaW, a docking surface centered around residues Arg⁸³, Lys¹⁰⁴ and Lys¹¹⁷ was hypothesized. The presented results might contribute to the development of TMA-lowering strategies that could reduce the risk for cardiovascular disease.

Therapeutic potential of traditional Chinese medicine against atherosclerosis: Targeting trimethylamine N-oxide

BACKGROUND

Recent studies have shown that plasma trimethylamine-N-oxide (TMAO) level is highly correlated with the risk of atherosclerosis (AS), and the elevated level is significantly positively correlated with the incidence of AS.

PURPOSE

The purpose of this article is to offer a useful summary of the correlation between TMAO and AS, and the effect of herbal monomers, herbal extracts, and formulas on anti-atherosclerosis mediated by TMAO.

METHOD

The data contained in this article comes from PubMed, Web of Science, and China National Knowledge Infrastructure.

RESULTS

This review discusses the main mechanism of AS induced by TMAO, including endothelial dysfunction, macrophage foaming, platelet reactivity, and cholesterol metabolism, and summarizes 6 herb monomers, 5 herb extracts, and 2 formulas that have been tested for their anti-TMAO activity.

CONCLUSION

The current understanding of possible ways to reduce TMAO generation is discussed, with the effect and potential of herb monomers, herb extracts, and formulas highlighted.

TMAO as a potential biomarker and therapeutic target for chronic kidney disease: A review

The gut microbiota and its metabolites have become a hotspot of recent research. Trimethylamine N-oxide (TMAO) metabolized by the gut microbiota is closely related to many diseases such as cardiovascular disease, chronic kidney disease, type 2 diabetes, etc. Chronic kidney disease (CKD) is an important contributor to morbidity and mortality from non-communicable diseases. Recently, increasing focus has been put on the role of TMAO in the development and progress of chronic kidney disease. The level of TMAO in patients with chronic kidney disease is significantly increased, and a high level of TMAO deteriorates chronic kidney disease. This article describes the relationship between TMAO and chronic kidney disease and the research progress of drugs targeted TMAO, providing a reference for the development of anti-chronic kidney disease drugs targeted TMAO.

Heat-Killed Lactiplantibacillus plantarum LRCC5314 Mitigates the Effects of Stress-Related Type 2 Diabetes in Mice via Gut Microbiome Modulation

The incidence of stress-related type 2 diabetes (stress-T2D), which is aggravated by physiological stress, is increasing annually. The effects of Lactobacillus, a key component of probiotics, have been widely studied in diabetes; however, studies on the effects of postbiotics are still limited. Here, we aimed to examine the mechanism through which heat-killed Lactiplantibacillus plantarum LRCC5314 (HK-LRCC5314) alleviates stress-T2D in a cold-induced stress-T2D C57BL/6 mouse model. HK-LRCC5314 markedly decreased body weight gain, adipose tissue (neck, subcutaneous, and epididymal) weight, and fasting glucose levels. In the adipose tissue, mRNA expression levels of stress-T2D associated factors (NPY, Y2R, GLUT4, adiponectin, and leptin) and pro-inflammatory factors (TNF-α, IL-6, and CCL-2) were also altered. Furthermore, HK-LRCC5314 increased the abundance of Barnesiella, Alistipes, and butyrate-producing bacteria, including Akkermansia, in feces and decreased the abundance of Ruminococcus, Dorea, and Clostridium. Thus, these findings suggest that HK-LRCC5314 exerts protective effects against stress-T2D via gut microbiome modulation, suggesting its potential as a supplement for managing stress-T2D.

Atherosclerosis amelioration by allicin in raw garlic through gut microbiota and trimethylamine-N-oxide modulation

Cardiovascular disease (CVD) is strongly associated with the gut microbiota and its metabolites, including trimethylamine-N-oxide (TMAO), formed from metaorganismal metabolism of ʟ-carnitine. Raw garlic juice, with allicin as its primary compound, exhibits considerable effects on the gut microbiota. This study validated the benefits of raw garlic juice against CVD risk via modulation of the gut microbiota and its metabolites. Allicin supplementation significantly decreased serum TMAO in ʟ-carnitine-fed C57BL/6 J mice, reduced aortic lesions, and altered the fecal microbiota in carnitine-induced, atherosclerosis-prone, apolipoprotein E-deficient (ApoE-/-) mice. In human subjects exhibiting high-TMAO production, raw garlic juice intake for a week reduced TMAO formation, improved gut microbial diversity, and increased the relative abundances of beneficial bacteria. In in vitro and ex vivo studies, raw garlic juice and allicin inhibited γ-butyrobetaine (γBB) and trimethylamine production by the gut microbiota. Thus, raw garlic juice and allicin can potentially prevent cardiovascular disease by decreasing TMAO production via gut microbiota modulation.

Enterobacter aerogenes ZDY01 inhibits choline-induced atherosclerosis through CDCA-FXR-FGF15 axis

Atherosclerosis is the leading cause of cardiovascular diseases worldwide. Trimethylamine N-oxide (TMAO), a metabolite of intestinal flora from dietary quaternary amines, has been shown to be closely related to the development of atherosclerosis. Previous studies have shown that Enterobacter aerogenes ZDY01 significantly reduces the serum levels of TMAO and cecal trimethylamine (TMA) in Balb/c mice; however, its role in the inhibition of choline-induced atherosclerosis in ApoE^-/- mice remains unclear. Here, we demonstrated that E. aerogenes ZDY01 inhibited choline-induced atherosclerosis in ApoE^-/- mice fed with 1.3% choline by reducing cecal TMA and modulating CDCA-FXR/FGF15 axis. We observed that E. aerogenes ZDY01 decreased the cecal TMA and serum TMAO levels by utilizing cecal TMA as a nutrient, not by changing the expression of hepatic FMO3 and the composition of gut microbiota. Furthermore, E. aerogenes ZDY01 enhanced the expression of bile acid transporters and reduced the cecal CDCA levels, thereby attenuating the FXR/FGF15 pathway, upregulating the expression of Cyp7a1, promoting reverse cholesterol transport. Taken together, E. aerogenes ZDY01 attenuated choline-induced atherosclerosis in ApoE^-/- mice by decreasing cecal TMA and promoting reverse cholesterol transport, implying that E. aerogenes ZDY01 treatment might have therapeutic potential in atherosclerosis.

Modulation of gut microbiota by foods and herbs to prevent cardiovascular diseases

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.

Antibacterial Properties of Organosulfur Compounds of Garlic (Allium sativum)

Garlic (Allium sativum), a popular food spice and flavoring agent, has also been used traditionally to treat various ailments especially bacterial infections for centuries in various cultures around the world. The principal phytochemicals that exhibit antibacterial activity are oil-soluble organosulfur compounds that include allicin, ajoenes, and allyl sulfides. The organosulfur compounds of garlic exhibit a range of antibacterial properties such as bactericidal, antibiofilm, antitoxin, and anti-quorum sensing activity against a wide range of bacteria including multi-drug resistant (MDR) strains. The reactive organosulfur compounds form disulfide bonds with free sulfhydryl groups of enzymes and compromise the integrity of the bacterial membrane. The World Health Organization (WHO) has recognized the development of antibiotic resistance as a global health concern and emphasizes antibiotic stewardship along with the urgent need to develop novel antibiotics. Multiple antibacterial effects of organosulfur compounds provide an excellent framework to develop them into novel antibiotics. The review provides a focused and comprehensive portrait of the status of garlic and its compounds as antibacterial agents. In addition, the emerging role of new technologies to harness the potential of garlic as a novel antibacterial agent is discussed.

Uraemic solutes as therapeutic targets in CKD-associated cardiovascular disease

Chronic kidney disease (CKD) is characterized by the retention of a myriad of solutes termed uraemic (or uremic) toxins, which inflict damage to several organs, including the cardiovascular system. Uraemic toxins can induce hallmarks of cardiovascular disease (CVD), such as atherothrombosis, heart failure, dysrhythmias, vessel calcification and dysregulated angiogenesis. CVD is an important driver of mortality in patients with CKD; however, reliance on conventional approaches to managing CVD risk is insufficient in these patients, underscoring a need to target risk factors that are specific to CKD. Mounting evidence suggests that targeting uraemic toxins and/or pathways induced by uraemic toxins, including tryptophan metabolites and trimethylamine N-oxide (TMAO), can lower the risk of CVD in patients with CKD. Although tangible therapies resulting from our growing knowledge of uraemic toxicity are yet to materialize, a number of pharmacological and non-pharmacological approaches have the potential to abrogate the effects of uraemic toxins, for example, by decreasing the production of uraemic toxins, by modifying metabolic pathways induced by uraemic toxins such as those controlled by aryl hydrocarbon receptor signalling and by augmenting the clearance of uraemic toxins.

Development of a High-Throughput Method to Study the Inhibitory Effect of Phytochemicals on Trimethylamine Formation

Choline is metabolized by the gut microbiota into trimethylamine (TMA), the precursor of pro-atherosclerotic molecule trimethylamine N-oxide (TMAO). A reduction in TMA formation has shown cardioprotective effects, and some phytochemicals may reduce TMA formation. This study aimed to develop an optimized, high-throughput anaerobic fermentation methodology to study the inhibition of choline microbial metabolism into TMA by phenolic compounds with healthy human fecal starter. Optimal fermentation conditions were: 20% fecal slurry (1:10 in PBS), 100 µM choline, and 12 h fermentation. Additionally, 10 mM of 3,3-dimethyl-1-butanol (DMB) was defined as a positive TMA production inhibitor, achieving a ~50% reduction in TMA production. Gallic acid and chlorogenic acid reported higher TMA inhibitory potential (maximum of 80–90% TMA production inhibition), with IC₅₀ around 5 mM. Neither DMB nor gallic acid or chlorogenic acid reduced TMA production through cytotoxic effects, indicating mechanisms such as altered TMA-lyase activity or expression.

Use of dietary phytochemicals for inhibition of trimethylamine N-oxide formation

Trimethylamine-N-oxide (TMAO) has been reported as a risk factor for atherosclerosis development, as well as for other cardiovascular disease (CVD) pathologies. The objective of this review is to provide a useful summary on the use of phytochemicals as TMAO-reducing agents. This review discusses the main mechanisms by which TMAO promotes CVD, including the modulation of lipid and bile acid metabolism, and the promotion of endothelial dysfunction and oxidative stress. Current knowledge on the available strategies to reduce TMAO formation are discussed, highlighting the effect and potential of phytochemicals. Overall, phytochemicals (i.e., phenolic compounds or glucosinolates) reduce TMAO formation by modulating gut microbiota composition and/or function, inhibiting host's capacity to metabolize TMA to TMAO, or a combination of both. Perspectives for design of future studies involving phytochemicals as TMAO-reducing agents are discussed. Overall, the information provided by this review outlines the current state of the art of the role of phytochemicals as TMAO reducing agents, providing valuable insight to further advance in this field of study.

Can diet modulate trimethylamine N-oxide (TMAO) production? What do we know so far?

BACKGROUND

Trimethylamine N-oxide (TMAO) is a metabolite that has attracted attention due to its positive association with several chronic non-communicable diseases such as insulin resistance, atherosclerotic plaque formation, diabetes, cancer, heart failure, hypertension, chronic kidney disease, liver steatosis, cardiac fibrosis, endothelial injury, neural degeneration and Alzheimer's disease. TMAO production results from the fermentation by the gut microbiota of dietary nutrients such as choline and carnitine, which are transformed to trimethylamine (TMA) and converted into TMAO in the liver by flavin-containing monooxygenase 1 and 3 (FMO1 and FMO3). Considering that TMAO is involved in the development of many chronic diseases, strategies have been found to enhance a healthy gut microbiota. In this context, some studies have shown that nutrients and bioactive compounds from food can modulate the gut microbiota and possibly reduce TMAO production.

OBJECTIVE

This review has as main objective to discuss the studies that demonstrated the effects of food on the reduction of this harmful metabolite.

METHODS

All relevant articles until November 2020 were included. The articles were searched in Medline through PubMed.

RESULTS

Both the food is eaten acutely and chronically, by altering the nature of the gut microbiota, influencing colonic TMA production. Furthermore, hepatic production of TMAO by the flavin monooxygenases in the liver may also be influenced by phenolic compounds present in foods.

CONCLUSION

The evidence presented in this review shows that TMAO levels can be reduced by some bioactive compounds. However, it is crucial to notice that there is significant variation among the studies. Further clinical studies should be conducted to evaluate these dietary components' effectiveness, dose, and intervention time on TMAO levels and its precursors.

TMAO: how gut microbiota contributes to heart failure

An increasing amount of evidence reveals that the gut microbiota is involved in the pathogenesis and progression of various cardiovascular diseases. In patients with heart failure (HF), splanchnic hypoperfusion causes ischemia and intestinal edema, allowing bacterial translocation and bacterial metabolites to enter the blood circulation via an impaired intestinal barrier. This results in local and systemic inflammatory responses. Gut microbe-derived metabolites are implicated in the pathology of multiple diseases, including HF. These landmark findings suggest that gut microbiota influences the host's metabolic health, either directly or indirectly by producing several metabolites. In this review, we mainly discuss a newly identified gut microbiota-dependent metabolite, trimethylamine N-oxide (TMAO), which appears to participate in the pathologic processes of HF and can serve as an early warning marker to identify individuals who are at the risk of disease progression. We also discuss the potential of the gut-TMAO-HF axis as a new target for HF treatment and highlight the current controversies and potentially new and exciting directions for future research.

Food as medicine: targeting the uraemic phenotype in chronic kidney disease

The observation that unhealthy diets (those that are low in whole grains, fruits and vegetables, and high in sugar, salt, saturated fat and ultra-processed foods) are a major risk factor for poor health outcomes has boosted interest in the concept of 'food as medicine'. This concept is especially relevant to metabolic diseases, such as chronic kidney disease (CKD), in which dietary approaches are already used to ameliorate metabolic and nutritional complications. Increased awareness that toxic uraemic metabolites originate not only from intermediary metabolism but also from gut microbial metabolism, which is directly influenced by diet, has fuelled interest in the potential of 'food as medicine' approaches in CKD beyond the current strategies of protein, sodium and phosphate restriction. Bioactive nutrients can alter the composition and metabolism of the microbiota, act as modulators of transcription factors involved in inflammation and oxidative stress, mitigate mitochondrial dysfunction, act as senolytics and impact the epigenome by altering one-carbon metabolism. As gut dysbiosis, inflammation, oxidative stress, mitochondrial dysfunction, premature ageing and epigenetic changes are common features of CKD, these findings suggest that tailored, healthy diets that include bioactive nutrients as part of the foodome could potentially be used to prevent and treat CKD and its complications.

The Relationship between Choline Bioavailability from Diet, Intestinal Microbiota Composition, and Its Modulation of Human Diseases

Choline is a water-soluble nutrient essential for human life. Gut microbial metabolism of choline results in the production of trimethylamine (TMA), which, upon absorption by the host is converted into trimethylamine-N-oxide (TMAO) in the liver. A high accumulation of both components is related to cardiovascular disease, inflammatory bowel disease, non-alcoholic fatty liver disease, and chronic kidney disease. However, the relationship between the microbiota production of these components and its impact on these diseases still remains unknown. In this review, we will address which microbes contribute to TMA production in the human gut, the extent to which host factors (e.g., the genotype) and diet affect TMA production, and the colonization of these microbes and the reversal of dysbiosis as a therapy for these diseases.

Dietary bioactive ingredients to modulate the gut microbiota-derived metabolite TMAO. New opportunities for functional food development

There is a growing body of clinical evidence that supports a strong association between elevated circulating trimethylamine N-oxide (TMAO) levels with increased risk of developing adverse cardiovascular outcomes such as atherosclerosis and thrombosis. TMAO is synthesized through a meta-organismal stepwise process that involves (i) the microbial production of TMA in the gut from dietary precursors and (ii) its subsequent oxidation to TMAO by flavin-containing monooxygenases in the liver. Choline, l-carnitine, betaine, and other TMA-containing compounds are the major dietary precursors of TMA. TMAO can also be absorbed directly from the gastrointestinal tract after the intake of TMAO-rich foods such as fish and shellfish. Thus, diet is an important factor as it provides the nutritional precursors to eventually produce TMAO. A number of studies have attempted to associate circulating TMAO levels with the consumption of diets rich in these foods. On the other hand, there is growing interest for the development of novel food ingredients that reduce either the TMAO-induced damage or the endogenous TMAO levels through the interference with microbiota and host metabolic processes involved in TMAO pathway. Such novel functional food ingredients would offer great opportunities to control circulating TMAO levels or its effects, and potentially contribute to decrease cardiovascular risk. In this review we summarize and discuss current data regarding the effects of TMA precursors-enriched foods or diets on circulating TMAO levels, and recent findings regarding the circulating TMAO-lowering effects of specific foods, food constituents and phytochemicals found in herbs, individually or in extracts, and their potential beneficial effect for cardiovascular health.

Bioavailability Based on the Gut Microbiota: a New Perspective

The substantial discrepancy between the strong effects of functional foods and various drugs, especially traditional Chinese medicines (TCMs), and the poor bioavailability of these substances remains a perplexing problem. Understanding the gut microbiota, which acts as an effective bioreactor in the human intestinal tract, provides an opportunity for the redefinition of bioavailability. Here, we discuss four different pathways associated with the role of the gut microbiota in the transformation of parent compounds to beneficial or detrimental small molecules, which can enter the body's circulatory system and be available to target cells, tissues, and organs. We further describe and propose effective strategies for improving bioavailability and alleviating side effects with the help of the gut microbiota. This review also broadens our perspectives for the discovery of new medicinal components.

Allicin Modifies the Composition and Function of the Gut Microbiota in Alcoholic Hepatic Steatosis Mice

The intestinal microbiome plays an important role in the pathogenesis of liver diseases. Alcohol intake induces gut microbiota dysbiosis and alters its function. This study investigated the antibiotic effect of allicin in mice with hepatic steatosis. Male C57BL/6 mice were administered an ethanol diet supplemented with allicin (5 and 20 mg/(kg bw day)) for 4 weeks. Allicin modified the gut microbiota composition. Cecal microbiota exhibited a positive correlation with alcohol and hepatic triacylglycerol, but were suppressed with allicin. Ethanol diet with 5 mg of allicin induced a lower intestinal permeability compared to the ethanol diet alone. Allicin mediated the lipopolysaccharide (LPS)-CD14-toll-like receptor 4 (TLR4)-induced hepatic inflammation pathway by reducing LPS, CD14, TLR4, and pro-inflammatory cytokines-tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. However, hepatic inflammation primarily resulted from alcohol toxicity rather than LPS production in the gut. The prediction of functional profiles from metagenomic 16S ribosomal RNA (rRNA) data revealed different functional profiles in each group. The predicted aldehyde dehydrogenase tended to increase in alcoholic mice administered allicin. The predicted LPS-related pathway and LPS biosynthesis protein results exhibited a similar trend as plasma LPS levels. Thus, alcohol and allicin intake shapes the gut microbiota and its functional profile and improves the CD14-TLR4 pathway to alleviate inflammation in the liver.

Background Diet Influences TMAO Concentrations Associated with Red Meat Intake without Influencing Apparent Hepatic TMAO-Related Activity in a Porcine Model

Red meat has been associated with an increased cardiovascular disease (CVD) risk, possibly through gut microbial-derived trimethylamine-N-oxide (TMAO). However, previous reports are conflicting, and influences from the background diet may modulate the impact of meat consumption. This study investigated the effect of red and white meat intake combined with two different background diets on urinary TMAO concentration and its association with the colon microbiome in addition to apparent hepatic TMAO-related activity. For 4 weeks, 32 pigs were fed chicken or red and processed meat combined with a prudent or western background diet. ¹H NMR-based metabolomics analysis was conducted on urine samples and hepatic Mrna expression of TMAO-related genes determined. Lower urinary TMAO concentrations were observed after intake of red and processed meat when consumed with a prudent compared to a western background diet. In addition, correlation analyses between urinary TMAO concentrations and relative abundance of colon bacterial groups suggested an association between TMAO and specific bacterial taxa. Diet did not affect the hepatic Mrna expression of genes related to TMAO formation. The results suggest that meat-induced TMAO formation is regulated by mechanisms other than alterations at the hepatic gene expression level, possibly involving modulations of the gut microbiota.

The Microbial Metabolite Trimethylamine N-Oxide Links Vascular Dysfunctions and the Autoimmune Disease Rheumatoid Arthritis

Diet and microbiota each have a direct impact on many chronic, inflammatory, and metabolic diseases. As the field develops, a new perspective is emerging. The effects of diet may depend on the microbiota composition of the intestine. A diet that is rich in choline, red meat, dairy, or egg may promote the growth, or change the composition, of microbial species. The microbiota, in turn, may produce metabolites that increase the risk of cardiovascular disease. This article reviews our current understanding of the effects of the molecule trimethylamine-N-oxide (TMAO) obtained from food or produced by the microbiota. We review the mechanisms of actions of TMAO, and studies that associate it with cardiovascular and chronic kidney diseases. We introduce a novel concept: TMAO is one among a group of selective uremic toxins that may rise to high levels in the circulation or accumulate in various organs. Based on this information, we evaluate how TMAO may harm, by exacerbating inflammation, or may protect, by attenuating amyloid formation, in autoimmune diseases such as rheumatoid arthritis.

Identification of TMAO-producer phenotype and host-diet-gut dysbiosis by carnitine challenge test in human and germ-free mice

OBJECTIVE

The gut microbiota-derived metabolite, trimethylamine N-oxide (TMAO) plays an important role in cardiovascular disease (CVD). The fasting plasma TMAO was shown as a prognostic indicator of CVD incident in patients and raised the interest of intervention targeting gut microbiota. Here we develop a clinically applicable method called oral carnitine challenge test (OCCT) for TMAO-related therapeutic drug efforts assessment and personalising dietary guidance.

DESIGN

A pharmacokinetic study was performed to verify the design of OCCT protocol. The OCCT was conducted in 23 vegetarians and 34 omnivores to validate gut microbiota TMAO production capacity. The OCCT survey was integrated with gut microbiome, host genotypes, dietary records and serum biochemistry. A humanised gnotobiotic mice study was performed for translational validation.

RESULTS

The OCCT showed better efficacy than fasting plasma TMAO to identify TMAO producer phenotype. The omnivores exhibited a 10-fold higher OR to be high TMAO producer than vegetarians. The TMAO-associated taxa found by OCCT in this study were consistent with previous animal studies. The TMAO producer phenotypes were also reproduced in humanised gnotobiotic mice model. Besides, we found the faecal CntA gene was not associated with TMAO production; therefore, other key relevant microbial genes might be involved. Finally, we demonstrated the urine TMAO exhibited a strong positive correlation with plasma TMAO (r=0.92, p<0.0001) and improved the feasibility of OCCT.

CONCLUSION

The OCCT can be used to identify TMAO-producer phenotype of gut microbiota and may serve as a personal guidance in CVD prevention and treatment.

TRIAL REGISTRATION NUMBER

NCT02838732; Results.

An in vitro exploratory study of dietary strategies based on polyphenol-rich beverages, fruit juices and oils to control trimethylamine production in the colon

Trimethylamine-N-oxide (TMAO) has been described as a new biomarker of cardiovascular disease (CVD), derived from gut microbial biotransformation of dietary choline and l-carnitine into trimethylamine (TMA) and subsequent hepatic oxidation. (Poly)phenols are among the dietary factors able to interfere with microbial enzymatic activity, possibly modulating TMA biotransformation at the gut level. The aim of this work was to investigate the in vitro biotransformation of choline and carnitine using faecal starters obtained from omnivorous and vegetarian subjects and the effect of (poly)phenol-rich foods on TMA production. Choline and l-carnitine were fermented with vegetarian or omnivorous faecal slurries, alone or in combination with 10 (poly)phenol-rich food items. TMA production from carnitine, but not from choline, was significantly lower when vegetarian faecal starters were used and, among the tested food items, blonde orange juice significantly reduced TMA formation during faecal biotransformation. Consequently, the main compounds of orange juice, namely phenolic compounds, terpenes, limonoids, organic acids and sugars, were tested individually. Sugars exerted the highest inhibitory effect on TMA production. Despite some limitations deriving from the applied in vitro model, this is the first work describing a possible role of some (poly)phenol-rich dietary products on the modulation of TMA colonic production. Free sugars were the main factor responsible for TMA inhibition, suggesting a potential beneficial role of colonic fermentation of carbohydrates in reducing TMA formation from its precursor molecules. This work opens new research directions to evaluate the effect of dietary fermentable fibre on TMA production and, potentially, on circulating TMAO levels.

Alliin alters gut microbiota and gene expression of colonic epithelial tissues

Alliin is a natural organosulfur-containing phytochemical in garlic. It is possible that alliin can regulate the gut microbiota for its strong antimicrobial activity against many pathogens. Here, we assessed whether alliin impacts the distal small intestinal bacteria, hence the cecal microbiota, thus altering the gene expression of colonic epithelial tissues (CETs). Eighty mg/kg alliin was orally administered to rats for 14 days, and the 16S rDNA from small intestinal and cecal microbiota as well as mRNA from CETs were sequenced and analyzed. The results showed that alliin consumption affected microbiota composition in both the small intestine and cecum, although there was only one specific genus, Allobaculum that was significantly altered in the rat cecum. The altered composition of microbiota indirectly impacted 174 genes in the CETs. Specifically, five genes, including RT1-Ba, RT1-Bb, Cd80, Madcam1, and Aicda, indicated this consumption related to the intestinal immune network for IgA production. PRACTICAL APPLICATIONS: We firstly reported alliin consumption in vivo potentially affected the intestinal immunity of healthy rats by slightly alteration of microbiota composition in small intestine and cecum. The alteration subsequently amplified, resulting in the change of the colonic epithelial expression of several genes related to the intestinal immune network for IgA production. Hence, we suggested the alliin consumption may potentially affect the immune system of healthy individuals by alteration of gut microbiota and epithelial gene expression.

Lactobacillus plantarum ZDY04 exhibits a strain-specific property of lowering TMAO via the modulation of gut microbiota in mice

Trimethylamine N-oxide (TMAO), which is oxidized from trimethylamine (TMA) by hepatic flavin-containing monooxygenases (FMOs), promotes the development of atherosclerosis and is a new target for the prevention and treatment of cardiovascular disease from the perspective of intestinal flora. TMA is transformed by intestinal flora from TMA-containing nutrients, such as choline. Some small molecular agents lower serum TMAO and/or cecal TMA levels. However, probiotics that can effectively reduce serum TMAO levels are currently lacking. In this work, five potentially probiotic strains were administered to mice supplemented with 1.3% choline. Only Lactobacillus plantarum ZDY04 significantly reduced serum TMAO and cecal TMA levels by modulating the relative abundance of the families Lachnospiraceae, Erysipelotrichaceae and Bacteroidaceae and the genus Mucispirillum in mice and not by influencing the expression levels of hepatic FMO3 and metabolizing choline, TMA, and TMAO. In addition, L. plantarum ZDY04 can significantly inhibit the development of TMAO-induced atherosclerosis in ApoE-/- 1.3% choline-fed mice as compared with the untreated PBS group. In conclusion, the use of L. plantarum ZDY04 may be an alternative approach to reduce serum TMAO levels and TMAO-induced atherosclerosis in mice.

Cross-Talk between Gut Microbiota and Heart via the Routes of Metabolite and Immunity

Considering the prevalence of cardiovascular disease (CVD), significant interest has been focused on the gut microbiota-heart interaction because the gut microbiota has been recognized as a barometer of human health. Dysbiosis, characterized by changes in the gut microbiota in CVD, has been reported in cardiovascular pathologies, such as atherosclerosis, hypertension, and heart failure. Conversely, gut microbiota-derived metabolites, such as trimethylamine/trimethylamine N-oxide (TMA/TMAO), can impact host physiology. Further, bacterial dysbiosis can disturb gut immunity, which increases the risk of acute arterial events. Moreover, studies of germ-free mice have provided evidence that microbiota diversity and the presence of a specific microbe in the gut can affect immune cells in hosts. Therefore, the changes in the composition of the gut microbiota can affect host metabolism and immunity. Importantly, these effects are not only confined to the gut but also spreaded to distal organs. The purpose of the current review is to highlight the complex interplay between the microbiota and CVD via TMAO and different immune cells and discuss the roles of probiotics and nutrition interventions in modulating the intestinal microbiota as novel therapeutic targets of CVD.

Optimization of fecal sample processing for microbiome study - The journey from bathroom to bench

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.

Trimethylamine-N-Oxide (TMAO)-Induced Impairment of Cardiomyocyte Function and the Protective Role of Urolithin B-Glucuronide

One of the most recently proposed candidates as a potential trigger for cardiovascular diseases is trimethylamine-N-oxide (TMAO). Possible direct effects of TMAO on myocardial tissue, independent of vascular damage, have been only partially explored so far. In the present study, we assessed the detrimental direct effects of TMAO on cardiomyocyte contractility and intracellular calcium dynamics, and the ability of urolithin B-glucuronide (Uro B-gluc) in counteracting TMAO-induced cell damage. Cell mechanics and calcium transients were measured, and ultrastructural analysis was performed in ventricular cardiomyocytes isolated from the heart of normal adult rats. Cells were either untreated, exposed to TMAO, or to TMAO and Uro B-gluc. TMAO exposure worsened cardiomyocyte mechanics and intracellular calcium handling, as documented by the decrease in the fraction of shortening (FS) and the maximal rate of shortening and re-lengthening, associated with reduced efficiency in the intracellular calcium removal. Ultrastructurally, TMAO-treated cardiomyocytes also exhibited glycogen accumulation, a higher number of mitochondria and lipofuscin-like pigment deposition, suggesting an altered cellular energetic metabolism and a higher rate of protein oxidative damage, respectively. Uro B-gluc led to a complete recovery of cellular contractility and calcium dynamics, and morphologically to a reduced glycogen accumulation. We demonstrated for the first time a direct negative role of TMAO on cardiomyocyte functional properties and the ability of Uro B-gluc in counteracting these detrimental effects.

Clinical Relevance of Gastrointestinal Microbiota During Pregnancy: A Primer for Nurses

Emerging evidence about the human microbiome, a collective term for all the microorganisms living in and on the human body, consistently demonstrates the critical influence it has on host physiology and disease risk. The microbiota in the gastrointestinal (GI) tract has the most significant and far-reaching effect on human physiology. The maternal GI microbiota can decrease the risk of adverse pregnancy outcomes by modulating energy extraction, glucose metabolism, vitamin production, and host immunity essential for optimal maternal and neonatal health. Moreover, the maternal GI microbiota is thought to influence colonization of the fetus and neonate that may predispose them to different health trajectories. This article provides a basic understanding about the influence of the structure of the maternal GI microbiota, the fundamental role it plays during pregnancy, and the factors that influence the structure, and subsequently function, of the GI microbiota in the general and pregnant population. While only a small number of studies have examined this topic during pregnancy, the preponderance of the evidence supports the need to clarify baseline structure and function of GI microbiota and its associations with pregnancy outcomes. In addition, the results from the studies conducted in the general population can be extrapolated to pregnancy in many cases. This knowledge is essential for clinicians who need to understand the implications of the microbiota for disease and wellness in order to address the care factors that may adversely influence the GI microbiota during pregnancy.

Microbial diversity and composition in different gut locations of hyperlipidemic mice receiving krill oil

Low-dose (LD, 100 mg kg^-1 day^-1), moderate-dose (MD, 200 mg kg^-1 day^-1), and high-dose (HD, 600 mg kg^-1 day^-1) krill oil treatments have a stepwise, enhanced effect on alleviating hyperlipidemia, and 16S rRNA sequencing of the fecal samples demonstrates that krill oil treatment alters microbial communities. Feces may not represent all microbial communities in the gastrointestinal (GI) tract. Therefore, in this study, the stored ileal and colon samples collected from LD and HD groups were sequenced, and the location-specific modulations of microbial communities were observed after krill oil treatments. The 16S rRNA sequencing of the ileal samples showed that the LD and HD groups have similar patterns between control and high-fat diet (HFD) treatments, and six most abundant genera and 40 operational taxonomic units that respond to krill oil treatment were identified. However, the 16S rRNA sequencing of the colon samples showed that LD krill oil shifts the structure from the HFD to that of the control, whereas the HD group was distributed between the control and HFD groups. The corresponding most abundant genera and responsive OTUs totaled 4 and 45, respectively. In conclusion, different gastrointestinal tract locations contain different microbial communities. These results will help to provide a comprehensive understanding of the role of dietary krill oil in modulating the gut microbiota and alleviating hyperlipidemia.

Study on alterations of physiological functions in aged constipation rats with fluid-deficiency based on metabonomic and microbiology analysis

To clarify how constipation interferes with the normal physiological function of organisms,¹H NMR profiles combined with PCR-DGGE and 16s rRNA gene sequencing were used to investigate the relationship among constipation, metabolite and gut microbiota.

Fish oil affects the metabolic process of trimethylamine N-oxide precursor through trimethylamine production and flavin-containing monooxygenase activity in male C57BL/6 mice

Fish oil supplements could affect TMAO metabolic process through gut microbiota and FMOs.

Diet and Gut Microbial Function in Metabolic and Cardiovascular Disease Risk

Over the past decade, the gut microbiome has emerged as a novel and largely unexplored source of variability for metabolic and cardiovascular disease risk, including diabetes. Animal and human studies support several possible pathways through which the gut microbiome may impact health, including the production of health-related metabolites from dietary sources. Diet is considered important to shaping the gut microbiota; in addition, gut microbiota influence the metabolism of many dietary components. In the present paper, we address the distinction between compositional and functional analysis of the gut microbiota. We focus on literature that highlights the value of moving beyond surveys of microbial composition to measuring gut microbial functioning to delineate mechanisms related to the interplay between diet and gut microbiota in cardiometabolic health.

Diet Supplementation with Allicin Protects against Alcoholic Fatty Liver Disease in Mice by Improving Anti-inflammation and Antioxidative Functions

This study investigated the liver-protective effects of allicin, an active compound in fresh garlic, against alcoholic fatty liver disease (AFLD) and liver inflammation. Its effects were investigated in an AFLD model in male C57BL/6 mice, which were fed Lieber-DeCarli liquid diet containing ethanol. Allicin (5 and 20 mg/kg bw/day) was orally administered daily in the AFLD mice for 4 weeks. The results indicate that allicin promotes hepatoprotection by significantly reducing aspartate transaminase (AST) and alanine transaminase (ALT) levels (p < 0.05) in the plasma, which are key indicators of liver damage. Allicin reduced fat accumulation, increased glutathione and catalase levels, and decreased microsomal protein cytochrome P450 2E1 (CYP2E1) expression (p < 0.05) in the livers of the AFLD mice. Furthermore, allicin supplementation significantly decreased the levels of proinflammatory tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 and suppressed the expression of sterol regulatory element-binding protein-1 (SREBP-1) (p < 0.05). Additionally, it improved the hepatic alcohol dehydrogenase (ADH) activity (p < 0.05). Collectively, these findings demonstrate that allicin attenuates liver oxidative stress and inflammation.

Evidence-based assessment of lipoprotein(a) as a risk biomarker for cardiovascular diseases - Some answers and still many questions

The present article is aimed at outlining the current state of knowledge regarding the clinical value of lipoprotein(a) (Lp(a)) as a marker of cardiovascular disease (CVD) risk by summarizing the results of recent clinical studies, meta-analyses and systematic reviews. The literature supports the predictive value of Lp(a) on CVD outcomes, although the effect size is modest. Lp(a) would also appear to have an effect on cerebrovascular outcomes, however the effect appears even smaller than that for CVD outcomes. Consideration of apolipoprotein(a) (apo(a)) isoforms and LPA genetics in relation to the simple assessment of Lp(a) concentration may enhance clinical practice in vascular medicine. We also describe recent advances in Lp(a) research (including therapies) and highlight areas where further research is needed such as the measurement of Lp(a) and its involvement in additional pathophysiological processes.