Sweet legacy, bitter outcomes: sugar, sweeteners, and the microbial origins of a modern syndrome. An evidence-based narrative review

Abstract

The consumption of added sugars and artificial sweeteners has risen exponentially in recent decades, driven by industrial availability, food processing, and Western dietary patterns. This narrative review, adopting a critical and multidisciplinary perspective, traces the history of sugar in the human diet, examines the evolution and safety of noncaloric sweeteners, and analyzes their impact on the gut microbiota. Drawing on experimental evidence and recent clinical studies, it explores how excessive intake of sugars and sweeteners can induce dysbiosis by reducing bacterial diversity, promoting the growth of proinflammatory microorganisms, altering short-chain fatty acid production, and compromising epithelial barrier integrity. The pathogenic role of these alterations is discussed in relation to digestive and metabolic disorders such as obesity, type 2 diabetes, metabolic dysfunction-associated steatotic liver disease, and inflammatory bowel disease. The review also considers the social and commercial determinants that perpetuate population exposure to dysbiotic dietary patterns, particularly in contexts of socioeconomic vulnerability. It proposes an integrated approach to addressing the clinical impact of sugar and sweetener consumption-encompassing public health measures, real-food-based dietary interventions, structured nutritional education, and regulation of the food environment. Overall, it underscores the need to reconceptualize intestinal dysbiosis not merely as a biological phenomenon but as a deeply social one requiring coordinated strategies across primary care, digestive health, and nutrition policy.