D-Fagomine (1,2-dideoxynojirimycin) is a six-membered ring iminocyclitol that was first isolated from seeds of buckwheat (Fagopyrum sculentum Moench, Polygonaceae) and is also present in other plant sources such as mulberry (Morus Alba, Moraceae) leaves and gogi (Lycium chinense) roots. D-fagomine is present in common buckwheat-based foodstuffs in amounts ranging from 1 to 25 mg/kg or mg/L, it is stable during boiling, baking, frying and fermentation, and it is biosynthesised upon sprouting. The estimated total intake of D-fagomine resulting from a diet that includes such foodstuffs would be between 3 and 17 mg per day (mean for both genders; range from P5 to P95). In animal studies D-Fagomine lowers postprandial blood glucose. D-fagomine agglutinated Enterobacteriaceae (Escherichia coli, Salmonella enterica serovar Typhimurium), while it did not show this effect on Bifidobacterium spp. or Lactobacillus spp. D-fagomine significantly inhibited the adhesion of Enterobacteriaceae and promoted the adhesion of Lactobacillus acidophilus to intestinal mucosa. D-Fagomine did not show any effect on bacterial cell viability. D-fagomine may be used as a dietary ingredient or functional food component to reduce the health risks associated with an excessive intake of fast-digestible carbohydrates, or an excess of potentially pathogenic bacteria.