Differential Effects of Typical Korean Versus American-Style Diets on Gut Microbial Composition and Metabolic Profile in Healthy Overweight Koreans: A Randomized Crossover TrialOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This randomized crossover trial compared how three dietary patterns reshape the gut microbiome and host metabolome in the same people. The diets were a typical Korean diet, a typical American diet, and a recommended healthy American diet. Each diet lasted four weeks, separated by two-week washout periods. Stool, serum, and urine were collected before and after each diet. Gut bacteria were profiled by 16S rRNA sequencing, and metabolites were measured by nuclear magnetic resonance.
Who was studied?
Participants were healthy overweight Korean adults recruited near Seoul National University in Korea. Of 132 screened, 61 entered the trial and 54 completed paired samples. Inclusion required ages 25 to 65 and a body mass index of at least 23. Smokers, diabetics, and recent probiotic or antibiotic users were excluded. All meals were provided daily, and body weight was held roughly stable across all three diet periods.
What were the most important findings?
The Korean diet raised gut microbial diversity, while the two American diets did not. After the Korean diet, Firmicutes rose (p equals 0.016) and Bacteroidetes fell (p equals 0.006), increasing the Firmicutes-to-Bacteroidetes ratio (p equals 0.0042). The diets produced distinct genus-level signatures, with 23, 21, and 20 differential genera for the Korean, healthy American, and typical American diets. The Korean diet lowered branched-chain amino acids, while both American diets enriched ketone body metabolism, raising 3-hydroxybutyrate and acetone.
What are the greatest implications of this study?
The gut microbiome and host metabolome respond rapidly, within four weeks, to a change in cultural diet. Korean versus American diets differed more than the two American diets differed from each other. Microbiome and metabolite responses varied by each person's baseline enterotype, supporting personalized nutrition. Beneficial bacteria responded to different diets in different enterotype groups. Because participants were overweight adults in Korea, the findings may not generalize to leaner people or other populations.