Urbanization-Induced Gut Microbiome Dysbiosis and Type 2 Diabetes in Sub-Saharan Africa: A Systematic Review of Mechanisms and Indigenous Therapeutics

Sub-Saharan Africa is undergoing a rapid nutritional and epidemiological transition, characterized by a rising incidence of Type 2 Diabetes (T2D) among lean populations. While the "Westernization" of the gut microbiome is well-documented globally, the specific ecological shifts driving metabolic dysfunction in the African context remain under-synthesized. This systematic review aims to catalog diet-driven taxonomic alterations and evaluate their mechanistic link to T2D. A systematic search was conducted following PRISMA guidelines using PubMed, Scopus, and Google Scholar (2015–2026). Studies were included if they compared the gut microbiomes of urban vs. rural African populations and reported metabolic outcomes. Quality was assessed using the Newcastle-Ottawa Scale. Twelve studies meeting inclusion criteria were identified, representing a pooled cohort of N=6,097 participants across 22 countries. The analysis revealed a consistent "rural signature" marked by the enrichment of fiber-degrading Treponema and Prevotella ("VANISH" taxa). Urbanization was associated with the significant depletion of these guilds and a compensatory bloom of Bacteroides and Bifidobacterium. This taxonomic shift was statistically correlated with elevated fasting blood glucose, HbA1c, and diabetes prevalence in urban cohorts. Mechanistically, the loss of Treponema likely compromises SCFA-mediated insulin signaling, while the rise of mucin-degrading Bacteroides may drive metabolic endotoxemia. Urbanization in Africa is associated with the loss of key ancestral microbes that protect metabolic health. Given that commercial probiotics often contain taxa already enriched in urban Africans (Bifidobacterium), we propose that indigenous fermented foods (e.g., Ogi, Kunu), which provide a Lactobacillus-rich acidic niche, represent a more ecologically appropriate therapeutic strategy to restore metabolic homeostasis. All identified associations are observational, and causal inferences cannot be established.