Monosaccharides

KEY Fermenters: Oxidation or fermentation by gut bacteria producing acid; Use: Utilisation or assimilation by gut bacteria; Common: Combined use and O/F for widespread, moderate and minor gut colonisers (total bacteria: 500);

Monosaccharides	Common users	All users	Common fermenters	All fermenters	Example users	Prevalence in Food	Human digestion, metabolism, interactions	Structure
Glucose	92	680	322	1348	Abiotrophia defectiva; Acetivibrio ethanolgignens; Actinobaculum massiliense; Actinomyces graevenitzii; Actinomyces naeslundii; Actinomyces viscosus; Agathobaculum butyriciproducens;	Widespread, often in the form of polymers (starch, glycogen)	Readily absorbed and metabolised. All cells can utilise glucose
Galactose	48	356	163	629	Acetivibrio ethanolgignens; Actinomyces graevenitzii; Aggregatibacter aphrophilus; Anaerobutyricum hallii; Anaeroglobus geminatus; Anaerostipes caccae; Anaerostipes hadrus;	The unbound sugar is present in a wide variety of fruits and vegetables, albeit in relatively small amounts (Gross1991)	Human digestible; it is converted to glucose in the liver (Dashty2013)
Mannose	63	461	221	872	Abiotrophia defectiva; Acetivibrio ethanolgignens; Actinomyces viscosus; Agathobaculum butyriciproducens; Aggregatibacter aphrophilus; Alistipes finegoldii; Alistipes ihumii;	Widespread in fruits and vegetables. After simulated digestion, mannose was detected in many foods, such as apple, inulin, pumpkin and kiwifruit (Parkar2021)	Not human metabolised. Mannose is efficiently absorbed by the gut but excreted almost completely
Fructose	67	488	213	896	Abiotrophia defectiva; Acetivibrio ethanolgignens; Actinomyces graevenitzii; Actinomyces naeslundii; Aggregatibacter aphrophilus; Alloprevotella tannerae; Anaerococcus prevotii;	Widespread in fruits	Human digestible. The majority of low-level fructose is cleared by epithelial cells of the small intestine, while high fructose intake leads to saturation and translocation to the liver via the bloodstream (Jang2018)
D-arabinose	0	0	21	93	Bacteroides bouchesdurhonensis; Bacteroides congonensis; Bacteroides eggerthii; Bacteroides finegoldii; Bacteroides mediterraneensis; Bacteroides togonis; Blautia luti;	Rare sugar	Unlikely to be digested by humans. While arabinose is readily absorbed by the gut (Dashty2013), infused D-arabinose has been shown to be mainly excreted via the kidneys and doesn't respond to insulin (Segal1957)
L-arabinose	15	251	89	409	Agathobaculum butyriciproducens; Anaerostipes hadrus; Bacillus licheniformis; Bacillus subtilis; Bacteroides bouchesdurhonensis; Bacteroides caccae; Bacteroides congonensis;	Most commonly found as a constituent of hemicellulose and pectin polymers. After simulated digestion, arabinose was detected in apple, carrot and sweetcorn (Parkar2021)	Not really metabolised because it is poorly absorbed. Any absorption by the gut is likely degraded by the liver while a portion is known to be excreted in urine. Inhibits human sucrase (KrogMikkelsen2011)
Arabinose	18	145	63	180	Alloscardovia omnicolens; Bacteroides caccae; Bacteroides eggerthii; Bacteroides faecis; Bacteroides finegoldii; Bacteroides intestinalis; Bacteroides oleiciplenus;	Most commonly found as a constituent of hemicellulose and pectin polymers	Unlikely to be metabolised. While arabinose is readily absorbed by the gut (Dashty2013), infused D-arabinose has been shown to be mainly excreted via the kidneys and doesn't respond to insulin (Segal1957)
D-fucose	1	32	5	37	Blautia massiliensis; Intestinimonas massiliensis; Massilimicrobiota timonensis; Parabacteroides bouchesdurhonensis; Serratia marcescens;
Fucose	15	105	20	71	Abiotrophia defectiva; Bacteroides congonensis; Bacteroides fragilis; Bacteroides ovatus; Bacteroides thetaiotaomicron; Bifidobacterium breve; Blautia luti;	Human milk, mushrooms, fruits, vegetables, seaweed and as a constituent of oligosaccharides (e.g. fucoidan, fucogalactans). After simulated digestion, fucose was detected in apple and kiwifruit (Parkar2021)	Metabolised by humans; L-fucose can be salvaged by cells and incorporated into more complex structures (Becker2003)
D-lyxose	5	31	8	46	Anaerostipes caccae; Bifidobacterium scardovii; Blautia massiliensis; Enterococcus avium; Intestinimonas massiliensis; Massilimicrobiota timonensis; Negativibacillus massiliensis;	Rare sugar, occurring as a component of bacterial glycolipids	Limited metabolism. Infused D-lyxose is mainly excreted via the kidneys but does respond to insulin (Segal1957)
Psicose	1	31	0	0		Rare sugar present in processed cane and beet molasses, coffee and wheat (Oshima2006)	Can be metabolised by humans. Transported via GLUT5 in the enterocyte and further transported using GLUT2; low caloric content (Ahmed2022)
Rhamnose	25	194	68	271	Agathobaculum butyriciproducens; Alistipes finegoldii; Alistipes indistinctus; Bacteroides caccae; Bacteroides cellulosilyticus; Bacteroides clarus; Bacteroides congonensis;	Isolated from Buckthorn and in a bound form in other plants. After simulated digestion, rhamnose was detected in blackcurrant and carrot (Parkar2021)	Limited metabolism. Rhamnose is poorly absorbed and can be excreted in the urine (Jenkins1994). A mixture of rhamnose, mannitol and lactulose, has been used to estimate small intestine permeability. The mixture is excreted essentially unchanged in the urine (Mahmood2007)
Ribose	28	238	86	464	Actinobaculum massiliense; Anaerococcus prevotii; Bacillus cereus; Bacillus licheniformis; Bacillus subtilis; Bacteroides bouchesdurhonensis; Bacteroides caccae;	Widespread in meat, fish, mushrooms and dairy products	Possibly metabolised. D-Ribose is rapidly absorbed (Dashty2013) but can be excreted in the urine. Higher doses can cause diarrhoea.
Sorbose	6	23	11	55	Anaerostipes caccae; Anaerostipes hadrus; Bacteroides congonensis; Blautia coccoides; Collinsella bouchesdurhonensis; Enterococcus avium; Escherichia coli;	From grapes, pasta and peppers	Probably metabolised, but no clear data (Smith2021, Yamada2014, Ahmed2022)
D-tagatose	0	28	26	100	Anaerostipes caccae; Bacillus licheniformis; Bacteroides togonis; Blautia massiliensis; Blautia stercoris; Clostridium tertium; Collinsella bouchesdurhonensis;	Rare natural sugar found in apples, oranges and pineapple. Isolated from the tree <i>Sterculia setigera</i>, as well as heated cows milk and other dairy products. Synthesised in bulk from lactose	Human metabolism occurs. Transported via GLUT5 in the enterocyte, metabolized via glycolytic pathway. However, absorption is poor (Buemann2000, Ahmed2022)
Xylose	42	320	123	526	Actinobaculum massiliense; Agathobaculum butyriciproducens; Alistipes finegoldii; Alistipes indistinctus; Alloscardovia omnicolens; Amedibacillus dolichus; Anaerotignum lactatifermentans;	After simulated digestion, xylose was detected in apple, blackcurrant, sweetcorn and kiwifruit (Parkar2021)	Limited metabolism. Absorbed via carrier-mediated transport (jejunum), but poorly metabolised (Jenkins1994). Infused D-xylose is partly excreted via the kidneys but does respond to insulin (Segal1957)
L-xylose	0	0	4	25	Blautia massiliensis; Intestinimonas massiliensis; Massilimicrobiota timonensis; Parabacteroides bouchesdurhonensis;