Kimchi improves irritable bowel syndrome: results of a randomized, double-blind placebo-controlled study

Dietary management of irritable bowel syndrome: considerations, challenges, and solutions

Diet is a cornerstone in the management of irritable bowel syndrome (IBS). There is evidence of efficacy across the spectrum of dietary management strategies, including some supplements (eg, specific fibres), foods, and whole diets (eg, a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols [known as the low-FODMAP diet]). Whole-diet interventions, in particular those that restrict intake, can be challenging to deliver effectively and safely. Factors to consider include patient demographics, food cost and availability, and the acceptability of dietary management and its impact on food-related quality of life. There is concern regarding a potential role of restrictive whole-diet interventions in eating disorder risk. Optimal approaches to delivering dietary management in the health-care setting are unclear. The aim of this Review is to summarise the clinical evidence for the dietary management of IBS; to discuss the challenges, burdens, and risks of dietary management; and to propose how these challenges, burdens, and risks should be mitigated and minimised in clinical practice.

Effects of Fermented Kimchi Consumption on Anthropometric and Blood Cardiometabolic Indicators: A Systematic Review and Meta-Analysis of Intervention Studies and Prospective Cohort Studies

CONTEXT

Increasing global kimchi consumption has prompted interest in its health impact. However, comprehensive reviews of the influence of kimchi on cardiometabolic risk factors, especially meta-analyses, remain limited.

OBJECTIVE

This review assessed the impact of fermented kimchi consumption on cardiometabolic risk factors by systematically reviewing human intervention and prospective cohort studies, and conducting a meta-analysis of intervention studies.

DATA SOURCES

A literature search of PubMed, EMBASE, Scopus, Web of Science, RISS, KISS, and ScienceON databases was conducted through April 30, 2024. The inclusion criteria encompassed studies that examined the effects of fermented kimchi, without any added ingredients or lactic acid bacteria, on health outcomes, including anthropometric measures, blood pressure, cardiometabolic and glycemic indicators, inflammatory cytokines, and the incidence of related chronic diseases.

DATA EXTRACTION

Data extraction and quality evaluation were conducted independently by 3 researchers.

DATA ANALYSIS

Pooled effect sizes were calculated as weighted mean differences (WMDs) with 95% CIs employing random-effects models.

RESULTS

Five intervention studies (205 participants) and 4 prospective cohort studies (42 455 participants) were selected. A meta-analysis of the intervention studies revealed a significant reduction in fasting blood glucose (WMD: -1.93 mg/dL; 95% CI: -3.82, -0.03; I2 = 17.4%) following the consumption of fermented kimchi. After excluding studies that contributed to increased heterogeneity, significant inverse associations were observed between fermented kimchi consumption and triglycerides (WMD: -28.9 mg/dL; 95% CI: -53.2, -4.5; I2 = 0.0%), systolic blood pressure (WMD: -3.48 mmHg; 95% CI: -5.95, -1.01, I2 = 0.0%), and diastolic blood pressure (WMD: -2.68 mmHg; 95% CI: -4.75, -0.62; I2 = 0.0%). Prospective cohort studies linked higher kimchi intake with a lower incidence of cancer and metabolic syndrome and an increased likelihood of achieving normal body weight.

CONCLUSION

This review supports beneficial effects of fermented kimchi on cardiometabolic health. However, due to the limited number of studies, these findings should be interpreted cautiously, highlighting the need for further research in diverse populations.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration No. CRD42024532020.

The effects of fermented vegetables on the gut microbiota for prevention of cardiovascular disease

This study investigated the impact of regular consumption of fermented vegetables (FVs) on inflammation and the composition of the gut microbiota in adults at increased risk for cardiovascular disease. Eighty-seven adults ages 35-64 were randomized into an FV group, who consumed 100 g FVs daily at least five times per week for eight weeks, or a usual diet (UD) group. Blood and stool samples were obtained before and after the intervention. Dependent samples t tests and adjusted linear models were used for within- and between-group comparisons. The mean age and body mass index of participants were 45 years and 30 kg/m2, and 80% were female. Bloating or gas was the most common side effect reported (19.3% FV group vs. 9.4% UD group). There were no changes in C-reactive protein, oxidized low-density lipoprotein-receptor 1, angiopoietin-like protein 4, trimethylamine oxide, and lipopolysaccharide-binding protein or bacterial alpha diversity between groups. Our findings indicate that consuming 100 g of FVs for at least five days per week for eight weeks does not change inflammatory biomarkers or microbial alpha diversity as measured by the Shannon index. It is possible that higher doses of FVs are necessary to elicit a significant response by gut bacteria.

Our extended microbiome: The human-relevant metabolites and biology of fermented foods

One of the key modes of microbial metabolism occurring in the gut microbiome is fermentation. This energy-yielding process transforms common macromolecules like polysaccharides and amino acids into a wide variety of chemicals, many of which are relevant to microbe-microbe and microbe-host interactions. Analogous transformations occur during the production of fermented foods, resulting in an abundance of bioactive metabolites. In foods, the products of fermentation can influence food safety and preservation, nutrient availability, and palatability and, once consumed, may impact immune and metabolic status, disease expression, and severity. Human signaling pathways perceive and respond to many of the currently known fermented food metabolites, though expansive chemical novelty remains to be defined. Here we discuss several aspects of fermented food-associated microbes and metabolites, including a condensed history, current understanding of their interactions with hosts and host-resident microbes, connections with commercial probiotics, and opportunities for future research on human health and disease and food sustainability.

Commentary: When applying dietary therapies for gastrointestinal conditions, family values, culture, and social challenges matter

Some gastrointestinal conditions now have diet as a cornerstone to therapy. Three examples include the low-fermentable, oligosaccharide, disaccharide, monosaccharide, and polyol diet for irritable bowel syndrome, a gluten-free diet for celiac disease, and a hypoallergenic diet for eosinophilic esophagitis. All have been shown to be effective in Western or highly industrialized countries. However, these gastrointestinal conditions occur worldwide. Less is known regarding the effectiveness of dietary therapies in cultures and regions of dense religious and traditional practices where food is a central focus. This includes South Asia, the Mediterranean region, Africa, the Middle East, South America, and within Indigenous communities. Hence, there is a need to reproduce dietary intervention studies within cultures of dense traditional dietary practices to understand the applicability and acceptability of dietary therapy to establish generalizability. Furthermore, there is a need for nutrition experts to have a deep understanding of various cultural cuisines, practices, values, and customs. To achieve this, increasing the diversity of students in the sciences and having a diverse workforce of nutrition experts and health professionals that reflects the patient population will allow for more personalized care. In addition, there are social challenges, including a lack of medical insurance coverage, the cost of dietary interventions, and inconsistent nutrition messaging. Although there are many cultural considerations and social challenges to implementing effective dietary interventions around the world, these barriers are addressable through research methodologies that address culture and society challenges, and enhanced training of dietitians.

Catechin with Lactic Acid Bacteria Starters Enhances the Antiobesity Effect of Kimchi

The antiobesity effects of kimchi with catechin and lactic acid bacteria as starters were studied in C57BL/6 mice with high-fat diet (HFD)-induced obesity. We prepared four types of kimchi: commercial kimchi, standard kimchi, green tea functional kimchi, and catechin functional kimchi (CFK). Body weight and weight of adipose tissue were significantly lower in the kimchi-treated groups than in the HFD and Salt (HFD +1.5% NaCl) groups. In addition, in the CFK group, the serum levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol were significantly lower and those of high-density lipoprotein cholesterol were markedly higher than the corresponding levels in the HFD and Salt groups. Moreover, CFK reduced fat cells and crown-like structures in the liver and epididymal fat tissues. The protein expression of adipo/lipogenesis-related genes in the liver and epididymal fat tissues was significantly lower (1.90-7.48-fold) in the CFK group than in the HFD and Salt groups, concurrent with upregulation of lipolysis-related genes (1.71-3.38-fold) and downregulation of inflammation-related genes (3.17-5.06-fold) in epididymal fat tissues. In addition, CFK modulated the gut microbiomes of obese mice by increasing the abundance of Bacteroidetes (7.61%), while in contrast, Firmicutes (82.21%) decreased. In addition, the presence of the Erysipelotrichaceae (8.37%) family in the CFK group decreased, while the number of beneficial bacteria of the families, Akkermansiaceae (6.74%), Lachnospiraceae (14.95%), and Lactobacillaceae (38.41%), increased. Thus, CFK exhibited an antiobesity effect through its modulation of lipid metabolism and the microbiome.

Fermented Vegetables as a Potential Treatment for Irritable Bowel Syndrome

Foods and supplements containing microorganisms with expected beneficial effects are increasingly investigated and utilized in the treatment of human illness, including irritable bowel syndrome (IBS). Research points to a prominent role of gut dysbiosis in the multiple aberrations in gastrointestinal function, immune balance, and mental health seen in IBS. The proposition of the current Perspective is that fermented vegetable foods, in combination with a healthy and stable diet, may be particularly useful for addressing these disturbances. This is based on the recognition that plants and their associated microorganisms have contributed to shaping human microbiota and adaptation over evolutionary time. In particular, lactic acid bacteria with immunomodulatory, antipathogenic, and digestive properties are prevalent in products such as sauerkraut and kimchi. Additionally, by adjusting the salt content and fermentation time, products with a microbial and therapeutic potential beyond that of regular ferments could potentially be produced. Although more clinical data are required to make firm assertions, the low-risk profile, combined with biological considerations and reasoning and considerable circumstantial and anecdotal evidence, indicate that fermented vegetables are worthy of consideration by health professionals and patients dealing with IBS-related issues. To maximize microbial diversity and limit the risk of adverse effects, small doses of multiple products, containing different combinations of traditionally fermented vegetables and/or fruits, is suggested for experimental research and care.

Recent advances in developing butyrogenic functional foods to promote gut health

As one of the major short-chain fatty acids produced via microbial fermentation, butyrate serves as not only a preferred energy substrate but also an important signaling molecule. Butyrate concentrations in circulation, tissues, and gut luminal contents have important pathophysiological implications. The genetic capacity of butyrate biosynthesis by the gut microbiota is frequently compromised during aging and various disorders, such as inflammatory bowel disease, metabolic disorders and colorectal cancer. Substantial efforts have been made to identify potent butyrogenic substrates and butyrate-hyperproducing bacteria to compensate for butyrate deficiency. Interindividual butyrogenic responses exist, which are more strongly predicted by heterogeneity in the gut microbiota composition than by ingested prebiotic substrates. In this review, we catalog major food types rich in butyrogenic substrates. We also discuss the potential of butyrogenic foods with proven properties for promoting gut health and disease management using findings from clinical trials. Potential limitations and constraints in the current research are highlighted. We advocate a precise nutrition approach in designing future clinical trials by prescreening individuals for key gut microbial signatures when recruiting study volunteers. The information provided in this review will be conducive to the development of microbiota engineering approaches for enhancing the sustained production of butyrate.