Aug 21, 20233 min read

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Oral administration of sauerkraut juices in Wistar rats led to increased activity of glutathione S-transferase (GST) and NAD(P)H:quinone oxidoreductase 1 (NQO1), key liver and kidney detoxifying enzymes [94]. Certain lactic acid bacteria contained in sauerkraut generate conjugated linoleic acid [95], for which there is evidence of anti-carcinogenic and anti-atherosclerotic activity in animals [96,97]. Furthermore, Lactobacillus plantarum P2 isolated from sauerkraut significantly induced TNF-α and IL-12 expression and prevented adhesion and invasion of Caco-2 cells by Salmonella enteritidis [98]. Sauerkraut contains glucosinolate breakdown products including kaempferol, (a flavonoid) isothiocyanates, indole-3-carbinol, goitrin, allyl cyanide and nitriles [99]. The relevance of such phytochemicals to human health is unclear, however kaempferol has been shown to have radical scavenging activity, to protect from oxidative damage and to attenuate cytokine-induced reactive oxygen species in vitro [100]. Isothiocyanates have been shown to have antimicrobial properties, preventing the growth of a range of species, including E. coli, C. difficile, C. jejuni and C. perfringens [101].

Prior to fermentation, the kimchi mix contains a variety of different bacterial species within the Leuconostoc, Lactobacillus, Pseudomonas, Pantoea and Weissella genera [21] (Table 1). However, once fermentation has started, the bacterial diversity decreases and the bacterial community is rapidly dominated by the genus Leuconostoc within only three days of fermentation [21]. Within this genus, Leuconostoc citreum is the most abundant species prior to fermentation, but it is present in only a minor proportion after three days of fermentation, at which time point Leuconostoc gasicomitatum and Leuconostoc gelidum become dominant [21]. As kimchi can comprise a variety of ingredients, the microbial composition varies depending on the type and amount of the foods included. For example, a higher Lactobacillus concertation has been found when kimchi contains a higher garlic quantity [146], while the addition of red pepper powder leads to higher Weissella and lower Leuconostoc and Lactobacillus proportions [147]. Several archaea (e.g., Halococcus, Natronococcus) and yeast (e.g., Saccharomyces, Candida, Trichosporon) genera have also been identified in commercially available kimchi [22] (Table 3). An animal study showed that kimchi consumption, which contained Leuconostoc mesenteroides DRC 0211, may exhibit potential weight control properties in mice via reducing hepatic mRNA expression of adipogenesis-related genes and inflammation-related monocyte chemotactic protein-1 and interleukin-6 in epididymal fat tissue [148]. Reductions in serum total cholesterol, triglycerides, low-density lipoprotein cholesterol levels and atherogenic index have also being demonstrated in rats following consumption of kimchi fermented by Leuconostoc kimchi GJ2 [149]. A human study demonstrated that consumption of kimchi fermented for 8 weeks led to changes in expression of genes related to metabolic pathways and immunity [150]. In a mouse colitis model, Lactobacillus paracasei LS2, a strain isolated from kimchi, decreased cytokine production, myeloperoxidase activity, and the number of macrophages and neutrophils in the lamina propria lymphocytes, suggesting a potential anti-inflammatory effect [151]. Anti-carcinogenic properties have also been attributed to kimchi with an in vitro study demonstrating inhibition of gastric cancer cell growth [152]. Notably, as kimchi comprises a variety of ingredients, its impact on the gut microbiota and health is thought to result from a synergic effect of the microorganisms it contains, as well as the nutrient content (e.g., phytochemicals, fibre, vitamins) of the foods used in the preparation. For example, antimicrobial and antioxidant effects have also been attributed to food constituent of kimchi, such as red pepper seeds and garlic [153,154].