Can fermented kimchi alter the gut microbiota and influence metabolism?
Eight weeks of daily kimchi consumption was associated with a significant reduction in the ratio of Firmicutes to Bacteroidetes in obese women, according to findings published in Molecular Nutrition & Food Research. The Firmicutes/Bacteroidetes ratio is reportedly a good biomarker for obesity.
“[F]ermented kimchi, but not fresh kimchi, changed the expression level of several genes in blood that are mostly related to metabolic pathways and immunity,” wrote researchers from Dongguk University and Chunlab Inc. at Seoul National University.
“This phenomenon was accompanied by a decrease of genus Blautia and an increase of Prevotella and Bacteroides in the gut microbial population.
“Taken together, it is conceivable that consumption of fermented kimchi can either directly influence expression of human genes related to metabolic and immunity pathways or indirectly influence human metabolism by altering gut microbial composition.”
Gut health and obesity
The study adds to emerging body of science supporting the effects of gut microflora on metabolic factors and obesity.
A 2005 study by Jeffrey Gordon and his group at Washington University in St. Louis indicated that obese mice had lower levels of Bacteroidetes and higher levels of Firmicutes, compared with lean mice.
One year later and Dr Gordon’s reported similar findings in humans: The microbial populations in the gut are different between obese and lean people, and that when the obese people lost weight their microflora reverted back to that observed in a lean person, suggesting that obesity may have a microbial component (Nature, Vol. 444, pp. 1022-1023, 1027-1031).
A more recent paper from the same group in Science Translational Medicine (Vol. 3, 106ra106) reported that ingestion of probiotic bacteria produced a change in many metabolic pathways, particularly those related to carbohydrate metabolism.
The new study involved 24 obese women and investigated if fresh or fermented kimchi could influence the gut microbiota and human genome. Eight weeks of study indicated that fresh and fermented kimchi, “exerted differential effects on the obesity-related clinical parameters”.
Data showed that fermented kimchi altered gene expression linked to metabolism, immunity, blood circulation, digestion, and blood pressure. Indeed, an earlier trial (Nutrition Research 2011, Vol. 31, pp. 436-443.) reported that fermented kimchi could influence blood pressure, waist-hip ratio, glucose and insulin levels, and total cholesterol.
“Additionally, we found that the relative abundance of Bacteroides and Prevotella was increased while that of Blautia was decreased after intake of fermented kimchi,” wrote the researchers. “This indicates that the subjects of the fermented kimchi group might be aligned with a ‘lean enterotype’ pattern as Bacteroides was reported to show negative correlation with obesity and Prevotella was found to be dominant in subjects with a low fat, high fiber diet.”
The study was funded by the Globalization of Korean Food R&D program.
Source: Molecular Nutrition & Food Research
Published online ahead of print, doi: 10.1002/mnfr.201400780
“Contrasting effects of fresh and fermented kimchi consumption on gut microbiota composition and gene expression related to metabolic syndrome in obese Korean women”
Authors: K. Han, S. Bose, J-h. Wang, B-S. Kim, et al.