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Record Information
StatusDetected and Quantified
Creation Date2005-11-16 15:48:42 UTC
Update Date2020-04-23 20:52:56 UTC
Secondary Accession Numbers
  • HMDB0005761
  • HMDB00186
  • HMDB05761
Metabolite Identification
Common NameAlpha-Lactose
Descriptionalpha-Lactose is the major sugar present in milk and the main source of energy supplied to the newborn mammalian in its mother's milk. Lactose is also an important osmotic regulator of lactation. It is digested by the intestinal lactase (EC, an enzyme expressed in newborns. Its activity declines following weaning. As a result, adult mammals are normally lactose-intolerant and more than 75% of the human adult population suffers from lactase deficiency. Lactase deficiency is present in up to 80 percent of blacks and Latinos, and up to 100 percent of American Indians and Asians. Persons with lactose intolerance are unable to digest significant amounts of lactose. Common symptoms include abdominal pain and bloating, excessive flatus, and watery stool following the ingestion of foods containing lactose. A sizable number of adults believe they are lactose intolerant but do not actually have impaired lactose digestion, and some persons with lactase deficiency can tolerate moderate amounts of ingested lactose. A diagnosis of lactose intolerance can usually be made with a careful history supported by dietary manipulation. If necessary, diagnosis can be confirmed by using a breath hydrogen or lactose tolerance test. These mostly uncomfortable symptoms of lactose maldigestion are blamed for a variably dairy consumption. There is, however, emerging evidence that certain lactic acid-producing bacteria, which selectively consume prebiotics, may be beneficial against some lower intestinal diseases. Lactose maldigestion and lactose should perhaps be re-evaluated as a potential provider of such a prebiotic. Treatment consists primarily of avoiding lactose-containing foods. Lactase enzyme supplements may be helpful. The degree of lactose malabsorption varies greatly among patients with lactose intolerance, but most of them can ingest up to 350 mL of milk daily without symptoms. Lactose-intolerant patients must ensure adequate calcium intake. (PMID: 13130292 , 12216958 , 12197838 , 12018807 ). Lactose in the urine is a biomarker for the consumption of milk.
Anhydrous lactoseChEBI
Milk sugarChEBI
Fast-flo lactoseHMDB
Flowlac 100HMDB
Granulac 140mHMDB
Lactin (carbohydrate)HMDB
Lactohale 300HMDB
Lactose anhydrideHMDB
Lactose fast-floHMDB
Pharmatosa DCL 21HMDB
Pharmatose 21HMDB
Pharmatose 325mHMDB
Pharmatose DCL 15HMDB
Respitose ML 003HMDB
Respitose SV 003HMDB
Saccharum lactinHMDB
Sorbalac 400HMDB
Sorbolac 400HMDB
Tablettose 70HMDB
Tablettose 80HMDB
Zeparox epHMDB
Lactose, anhydrousHMDB
Chemical FormulaC12H22O11
Average Molecular Weight342.2965
Monoisotopic Molecular Weight342.116211546
IUPAC Name(2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-{[(2R,3S,4R,5R,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxy}oxane-3,4,5-triol
Traditional Nameα-lactose
CAS Registry Number63-42-3
InChI Identifier
Chemical Taxonomy
Description belongs to the class of organic compounds known as o-glycosyl compounds. These are glycoside in which a sugar group is bonded through one carbon to another group via a O-glycosidic bond.
KingdomOrganic compounds
Super ClassOrganic oxygen compounds
ClassOrganooxygen compounds
Sub ClassCarbohydrates and carbohydrate conjugates
Direct ParentO-glycosyl compounds
Alternative Parents
  • O-glycosyl compound
  • Disaccharide
  • Oxane
  • Secondary alcohol
  • Hemiacetal
  • Oxacycle
  • Organoheterocyclic compound
  • Polyol
  • Acetal
  • Hydrocarbon derivative
  • Primary alcohol
  • Alcohol
  • Aliphatic heteromonocyclic compound
Molecular FrameworkAliphatic heteromonocyclic compounds
External Descriptors

Route of exposure:


Biological location:


Naturally occurring process:


Industrial application:

Physical Properties
Experimental Properties
Melting Point201 - 202 °CNot Available
Boiling PointNot AvailableNot Available
Water Solubility195 mg/mL at 20 °CNot Available
LogPNot AvailableNot Available
Predicted Properties
Water Solubility586 g/LALOGPS
pKa (Strongest Acidic)11.25ChemAxon
pKa (Strongest Basic)-3ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count11ChemAxon
Hydrogen Donor Count8ChemAxon
Polar Surface Area189.53 ŲChemAxon
Rotatable Bond Count4ChemAxon
Refractivity68.34 m³·mol⁻¹ChemAxon
Polarizability30.92 ųChemAxon
Number of Rings2ChemAxon
Rule of FiveNoChemAxon
Ghose FilterNoChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon
Spectrum TypeDescriptionSplash KeyView
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (8 TMS)splash10-0uxs-0972000000-af8ca1bf1faa3d01a08dSpectrum
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (8 TMS; 1 MEOX)splash10-00di-9741000000-a61bf0223a1683f0402eSpectrum
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (8 TMS; 1 MEOX)splash10-00di-9641000000-12611bfab50cb066e8afSpectrum
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positivesplash10-03e9-4897000000-332d470623cd7f1e1cedSpectrum
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (4 TMS) - 70eV, Positivesplash10-014i-3513539000-d702fa4adb45f44530b6Spectrum
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 10V, Positive (Annotated)splash10-03di-0901000000-bcb7aaa42261d980d488Spectrum
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 25V, Positive (Annotated)splash10-000f-9300000000-1bc18b05388cd2213573Spectrum
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 40V, Positive (Annotated)splash10-01p9-9000000000-4483af567feecb34a651Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-03gl-0907000000-a1de7813fbe8b5258c10Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-03e9-0900000000-79cc5059a3f338e8c1ddSpectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-03di-3900000000-851d0bc84d91b6e09579Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-002f-0749000000-af1d18f2bc3ab8e02883Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-0200-2902000000-67218697344afb9e70faSpectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-01td-4900000000-40aa2d8125769803cfbbSpectrum
1D NMR1H NMR SpectrumNot AvailableSpectrum
1D NMR13C NMR SpectrumNot AvailableSpectrum
2D NMR[1H,1H] 2D NMR SpectrumNot AvailableSpectrum
2D NMR[1H,13C] 2D NMR SpectrumNot AvailableSpectrum
Biological Properties
Cellular Locations
  • Cytoplasm
  • Extracellular
  • Lysosome
  • Golgi apparatus
Biospecimen Locations
  • Blood
  • Breast Milk
  • Feces
  • Urine
Tissue Locations
  • Bladder
  • Epidermis
  • Intestine
  • Platelet
  • Skeletal Muscle
  • Spleen
Normal Concentrations
BloodExpected but not Quantified Not AvailableNot Available
    Breast MilkDetected and Quantified170000 +/- 7300 uMAdult (>18 years old)Female
    FecesDetected but not Quantified Infant (0-1 year old)Both
    UrineDetected and Quantified19.378 +/- 10.997 umol/mmol creatinineChildren (1 - 13 years old)Not Specified
      • Mordechai, Hien, ...
    UrineDetected and Quantified11.8 (1.0-24.2) umol/mmol creatinineAdult (>18 years old)Both
    UrineDetected and Quantified13.600-48.467 umol/mmol creatinineInfant (0-1 year old)Not SpecifiedNormal
      • Geigy Scientific ...
    UrineDetected and Quantified30.0 (13.0-49.0) umol/mmol creatinineInfant (0-1 year old)BothNormal
      • Geigy Scientific ...
    UrineDetected and Quantified1.45 (0.63-3.45) umol/mmol creatinineAdult (>18 years old)BothNormal
      • Geigy Scientific ...
    UrineDetected and Quantified36.31 +/- 6.60 umol/mmol creatinineAdult (>18 years old)Not Specified
    UrineDetected and Quantified66.02 +/- 6.60 umol/mmol creatinineAdult (>18 years old)Not Specified
    UrineDetected and Quantified676.75 +/- 85.83 umol/mmol creatinineNewborn (0-30 days old)Not Specified
    UrineDetected and Quantified6.08 +/- 6.07 umol/mmol creatinineInfant (0-1 year old)BothNormal details
    Abnormal Concentrations
    UrineDetected and Quantified51.475 +/- 126.985 umol/mmol creatinineChildren (1 - 13 years old)Not Specified
    Eosinophilic esophagitis
      • Mordechai, Hien, ...
    UrineDetected but not Quantified Adult (>18 years old)BothBladder cancer details
    UrineDetected and Quantified585 umol/mmol creatinineInfant (0-1 year old)MaleLactose Intolerance details
    Associated Disorders and Diseases
    Disease References
    Eosinophilic esophagitis
    1. (). Mordechai, Hien, and David S. Wishart. .
    Lactose Intolerance
    1. Hoskova A, Sabacky J, Mrskos A, Pospisil R: Severe lactose intolerance with lactosuria and vomiting. Arch Dis Child. 1980 Apr;55(4):304-5. [PubMed:7416780 ]
    Associated OMIM IDs
    DrugBank IDNot Available
    Phenol Explorer Compound IDNot Available
    FooDB IDFDB021789
    KNApSAcK IDC00001136
    Chemspider ID76293
    KEGG Compound IDC00243
    BiGG ID34366
    Wikipedia LinkNot Available
    METLIN ID267
    PubChem Compound84571
    PDB IDNot Available
    ChEBI ID36219
    Food Biomarker OntologyNot Available
    Synthesis ReferenceRuffing, Anne; Mao, Zichao; Ruizhen Chen, Rachel. Metabolic engineering of Agrobacterium sp. for UDP-galactose regeneration and oligosaccharide synthesis. Metabolic Engineering (2006), 8(5), 465-473.
    Material Safety Data Sheet (MSDS)Download (PDF)
    General References
    1. Jung SK, Fujimoto D: A novel beta-galactoside-binding lectin in adult rat kidney. J Biochem. 1994 Sep;116(3):547-53. [PubMed:7852273 ]
    2. Oozeer R, Furet JP, Goupil-Feuillerat N, Anba J, Mengaud J, Corthier G: Differential activities of four Lactobacillus casei promoters during bacterial transit through the gastrointestinal tracts of human-microbiota-associated mice. Appl Environ Microbiol. 2005 Mar;71(3):1356-63. [PubMed:15746338 ]
    3. Dimopoulos MA, Anagnostopoulos A: Thalidomide in relapsed/refractory multiple myeloma: pivotal trials conducted outside the United States. Semin Hematol. 2003 Oct;40(4 Suppl 4):8-16. [PubMed:15015891 ]
    4. Muthusamy A, Erickson DR, Sheykhnazari M, Bhavanandan VP: Enhanced binding of modified pentosan polysulfate and heparin to bladder--a strategy for improved treatment of interstitial cystitis. Urology. 2006 Jan;67(1):209-13. [PubMed:16413377 ]
    5. Johnson JD, Simoons FJ, Hurwitz R, Grange A, Mitchell CH, Sinatra FR, Sunshine P, Robertson WV, Bennett PH, Kretchmer N: Lactose malabsorption among the Pima indians of Arizona. Gastroenterology. 1977 Dec;73(6):1299-304. [PubMed:578795 ]
    6. Lustenberger RW: [A 23-year old patient with chronic diarrhea. Celiac disease and lactose intolerance]. Praxis (Bern 1994). 2005 Feb 2;94(5):163-4. [PubMed:15745382 ]
    7. Sharma A, DiCioccio RA, Allen HJ: Identification and synthesis of a novel 15 kDa beta-galactoside-binding lectin in human leukocytes. Glycobiology. 1992 Aug;2(4):285-92. [PubMed:1421750 ]
    8. Rana SV, Bhasin DK, Vinayak VK: Lactose hydrogen breath test in Giardia lamblia-positive patients. Dig Dis Sci. 2005 Feb;50(2):259-61. [PubMed:15745082 ]
    9. Mitchell JD, Brand J, Halbisch J: Weight-gain inhibition by lactose in Australian Aboriginal children. A controlled trial of normal and lactose hydrolysed milk. Lancet. 1977 Mar 5;1(8010):500-2. [PubMed:65606 ]
    10. Soupene E, van Heeswijk WC, Plumbridge J, Stewart V, Bertenthal D, Lee H, Prasad G, Paliy O, Charernnoppakul P, Kustu S: Physiological studies of Escherichia coli strain MG1655: growth defects and apparent cross-regulation of gene expression. J Bacteriol. 2003 Sep;185(18):5611-26. [PubMed:12949114 ]
    11. Yeoh E, Horowitz M, Russo A, Muecke T, Robb T, Chatterton B: The effects of abdominal irradiation for seminoma of the testis on gastrointestinal function. J Gastroenterol Hepatol. 1995 Mar-Apr;10(2):125-30. [PubMed:7787155 ]
    12. Bondesson E, Bengtsson T, Borgstrom L, Nilsson LE, Norrgren K, Olsson B, Svensson M, Wollmer P: Dose delivery late in the breath can increase dry powder aerosol penetration into the lungs. J Aerosol Med. 2005 Spring;18(1):23-33. [PubMed:15741771 ]
    13. Roberson CM: Lactose intolerance. Ala Nurse. 2004 Dec-2005 Feb;31(4):23-4; quiz 24. [PubMed:15662762 ]
    14. Kim KI, Lee WS, Benevenga NJ: Feeding diets containing high levels of milk products or cellulose decrease urease activity and ammonia production in rat intestine. J Nutr. 1998 Jul;128(7):1186-91. [PubMed:9649604 ]
    15. Gunther S, Patterson RE, Kristal AR, Stratton KL, White E: Demographic and health-related correlates of herbal and specialty supplement use. J Am Diet Assoc. 2004 Jan;104(1):27-34. [PubMed:14702580 ]
    16. Delaveau P: [Milk lactose. Hypothesis on its biological importance]. Ann Pharm Fr. 2003;61(5):340-2. [PubMed:13130292 ]
    17. Vilotte JL: Lowering the milk lactose content in vivo: potential interests, strategies and physiological consequences. Reprod Nutr Dev. 2002 Mar-Apr;42(2):127-32. [PubMed:12216958 ]
    18. Szilagyi A: Review article: lactose--a potential prebiotic. Aliment Pharmacol Ther. 2002 Sep;16(9):1591-602. [PubMed:12197838 ]
    19. Swagerty DL Jr, Walling AD, Klein RM: Lactose intolerance. Am Fam Physician. 2002 May 1;65(9):1845-50. [PubMed:12018807 ]


    General function:
    Involved in hydrolase activity, hydrolyzing O-glycosyl compounds
    Specific function:
    LPH splits lactose in the small intestine.
    Gene Name:
    Uniprot ID:
    Molecular weight:
    General function:
    Involved in transferase activity, transferring glycosyl groups
    Specific function:
    Responsible for the synthesis of complex-type N-linked oligosaccharides in many glycoproteins as well as the carbohydrate moieties of glycolipids. Can produce lactose.
    Gene Name:
    Uniprot ID:
    Molecular weight:
    General function:
    Involved in lactose synthase activity
    Specific function:
    Regulatory subunit of lactose synthase, changes the substrate specificity of galactosyltransferase in the mammary gland making glucose a good acceptor substrate for this enzyme. This enables LS to synthesize lactose, the major carbohydrate component of milk. In other tissues, galactosyltransferase transfers galactose onto the N-acetylglucosamine of the oligosaccharide chains in glycoproteins.
    Gene Name:
    Uniprot ID:
    Molecular weight:
    Not Available
    General function:
    Involved in transferase activity, transferring glycosyl groups
    Specific function:
    The Golgi complex form catalyzes the production of lactose in the lactating mammary gland and could also be responsible for the synthesis of complex-type N-linked oligosaccharides in many glycoproteins as well as the carbohydrate moieties of glycolipids. The cell surface form functions as a recognition molecule during a variety of cell to cell and cell to matrix interactions, as those occurring during development and egg fertilization, by binding to specific oligosaccharide ligands on opposing cells or in the extracellular matrix.
    Gene Name:
    Uniprot ID:
    Molecular weight:
    General function:
    Involved in hydrolase activity, hydrolyzing O-glycosyl compounds
    Specific function:
    Cleaves beta-linked terminal galactosyl residues from gangliosides, glycoproteins, and glycosaminoglycans. Isoform 2 has no beta-galactosidase catalytic activity, but plays functional roles in the formation of extracellular elastic fibers (elastogenesis) and in the development of connective tissue. Seems to be identical to the elastin-binding protein (EBP), a major component of the non-integrin cell surface receptor expressed on fibroblasts, smooth muscle cells, chondroblasts, leukocytes, and certain cancer cell types. In elastin producing cells, associates with tropoelastin intracellularly and functions as a recycling molecular chaperone which facilitates the secretions of tropoelastin and its assembly into elastic fibers.
    Gene Name:
    Uniprot ID:
    Molecular weight:
    Not Available
    General function:
    Involved in glycolipid transporter activity
    Specific function:
    Accelerates the intermembrane transfer of various glycolipids. Catalyzes the transfer of various glycosphingolipids between membranes but does not catalyze the transfer of phospholipids. May be involved in the intracellular translocation of glucosylceramides
    Gene Name:
    Uniprot ID:
    Molecular weight:
    1. Overington JP, Al-Lazikani B, Hopkins AL: How many drug targets are there? Nat Rev Drug Discov. 2006 Dec;5(12):993-6. [PubMed:17139284 ]
    2. Imming P, Sinning C, Meyer A: Drugs, their targets and the nature and number of drug targets. Nat Rev Drug Discov. 2006 Oct;5(10):821-34. [PubMed:17016423 ]