Diet changes due to urbanization in South Africa are linked to microbiome and metabolome signatures of Westernization and colorectal cancerOriginal 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 study asked how urbanization and Western diets in South Africa reshape the gut microbiome and metabolome, and how that relates to colorectal cancer risk. It was a cross-sectional, observational pilot study comparing rural and urban communities. Researchers measured dietary intake, fecal 16S bacteriome, virome, and metabolome (short-chain fatty acids and bile acids), plus food and skin microbiota.
Who was studied?
Participants were healthy middle-aged Black South Africans self-identifying as amaXhosa (Xhosa). The urban cohort (n=20) lived in Cape Town, and the rural cohort (n=24) lived in the Eastern Cape Province. Food samples came from 6 urban and 7 rural households. Virome analysis used 28 fecal samples (9 urban, 19 rural). Hand-swab skin sampling covered 6 urban and 7 rural participants.
What were the most important findings?
Urban participants ate far more energy (3,578 versus 2,185 kcal/day) plus more fat and animal protein, while the rural diet gave 72% of calories from carbohydrate. Urban feces had lower bacterial diversity, a shift from fiber-fermenting genera like Prevotella toward taxa linked to bile acid metabolism and colorectal cancer, and higher deoxycholic acid. Short-chain fatty acids, including butyrate, were similar between groups. Of 900 viral contigs, only 176 were shared; virome composition differed by urbanization and correlated with bile acids and dietary nutrients.
What are the greatest implications of this study?
The findings support the idea that dietary Westernization during urbanization pushes the gut microbiome toward patterns tied to non-communicable diseases like colorectal cancer. Higher deoxycholic acid and loss of fiber-degrading, butyrate-producing bacteria may raise cancer risk, even where fiber intake stays moderate. The authors propose restoring traditional diet components, such as diverse plant foods and fermentation. Limits include small sample size, two study sites, no colonic biopsies, and a cross-sectional design that cannot prove cause.