Lactose Intolerance
Lactose intolerance refers to a reduced ability to digest lactose, or milk sugar. Around 75% of the world's population is lactose intolerant to some degree, due to not producing the lactase enzyme in adulthood. Products like cheese and yogurt are lower in lactose than milk is, but some people can't handle any lactose at all without lactase enzyme supplementation. Occasional low-level dairy consumption may foster gut bacteria that help digest lactose.
Lactose Intolerance falls under theGut Healthcategory.
Last Updated:October 11, 2022
Lactose intolerance is a reduced ability to digest lactose, the main sugar found in milk. Most children and babies produce lactase enzyme, which splits the disaccharide lactose into its digestible component sugars (glucose and galactose), in their small intestine. However, in most of the global population, the production of lactase declines steeply in childhood, and around 70% of the world's adult population is lactose intolerant to some degree, due to reduced or no production of the lactase enzyme in adulthood.[1][2]
People with lactose intolerance experience digestive symptoms due to intestinal bacteria consuming the undigested lactose. Symptoms vary widely from person to person, and can include flatulence and bloating (from the excess gas produced by intestinal bacteria), borborygmus (a delightful word that refers to tummy rumbling from gas and liquid sloshing around), diarrhea (caused by osmotic pressure due to undigested lactose), abdominal pain, and nausea. Symptom onset is usually 30 minutes to 2 hours after ingesting lactose.[2]
Low to no production of lactase enzyme is actually the norm in adults; it’s not a disorder, and doesn’t require medical treatment per se. Lactose intolerance which occurs secondary to an illness is usually self-limiting; when the underlying condition is resolved, lactase production usually resumes without further treatment. In all cases, the digestive symptoms of lactose intolerance can be managed in one of three ways: by reducing dietary lactose until symptoms no longer occur; by supplementing with lactase enzyme; or by supplementing with probiotics.[2]
The principal supplement for lactose intolerance is lactase enzyme, taken orally with lactose-containing foods. Supplementing with lactase enzyme has been shown to be clinically effective at reducing or eliminating the digestive symptoms of lactose intolerance.[3][4][5][6][2] Probiotics have also been studied for lactose intolerance. Per a 2019 review, the probiotics that have been studied include Bifidobacterium longum, Bifidobacterium animalis, Lactobacillus bulgaricus, Lactobacillus reuteri, Lactobacillus acidophilus, Lactobacillus rhamnosus, Saccharomyces boulardii, and Streptococcus thermophilus. Of these, B. animalis had the best evidence for reducing symptoms of lactose intolerance.[7] A promising, but less-studied and proprietary, probiotic is a genetically modified strain of L. acidophilus that produces mammalian lactase. However, no research on this probiotic strain has been published in a peer-reviewed journal, and clinical trials are still ongoing.[8]
Dairy foods don’t all contain the same amount of lactose. Many people with lactose intolerance can consume moderate amounts of lactose (up to the equivalent of one cup of milk) without experiencing digestive symptoms,[9] making it possible to enjoy lower-lactose dairy foods on a low-lactose diet.[2] Medications and processed non-dairy foods may also have lactose added during processing–for example, Pop Rocks candy and Pringles Salt & Vinegar chips both contain lactose,[10][11] despite having no obvious connection to dairy–so people who experience symptoms with smaller amounts of lactose may need to check labels carefully.
Dietary changes and supplementary lactase enzyme are the best-studied tools for symptom management. Probiotics have also been studied for lactose intolerance; see “Have any supplements been studied for lactose intolerance?” above.
There are three types of lactose intolerance: primary, secondary, and congenital.[2]
- Primary lactose intolerance is the most common. This is the normal drop in intestinal lactase production that occurs for most people between ages two and five.
- Secondary lactose intolerance is a sudden decrease in lactase production due to damage to the small intestine. This is usually a transient condition resulting from conditions like infection, celiac disease, Crohn’s disease, food allergy, or small intestinal bacterial overgrowth (SIBO).[2]
- Congenital lactase deficiency (CLD) refers to an inability to produce lactase from birth. It’s an autosomal-recessive disorder, caused by a mutation in the LCT gene, and it is extremely rare.[12]
- ^Ugidos-Rodríguez S, Matallana-González MC, Sánchez-Mata MCLactose malabsorption and intolerance: a review.Food Funct.(2018-Aug-15)
- ^Di Costanzo M, Berni Canani RLactose Intolerance: Common Misunderstandings.Ann Nutr Metab.(2018)
- ^Ojetti V, Gigante G, Gabrielli M, Ainora ME, Mannocci A, Lauritano EC, Gasbarrini G, Gasbarrini AThe effect of oral supplementation with Lactobacillus reuteri or tilactase in lactose intolerant patients: randomized trialEur Rev Med Pharmacol Sci.(2010 Mar)
- ^Corazza GR, Benati G, Sorge M, Strocchi A, Calza G, Gasbarrini Gbeta-Galactosidase from Aspergillus niger in adult lactose malabsorption: a double-blind crossover studyAliment Pharmacol Ther.(1992 Feb)
- ^Solomons NW, Guerrero AM, Torun BDietary manipulation of postprandial colonic lactose fermentation: II. Addition of exogenous, microbial beta-galactosidases at mealtimeAm J Clin Nutr.(1985 Feb)
- ^Montalto M, Nucera G, Santoro L, Curigliano V, Vastola M, Covino M, Cuoco L, Manna R, Gasbarrini A, Gasbarrini GEffect of exogenous beta-galactosidase in patients with lactose malabsorption and intolerance: a crossover double-blind placebo-controlled studyEur J Clin Nutr.(2005 Apr)
- ^Oak SJ, Jha RThe effects of probiotics in lactose intolerance: A systematic review.Crit Rev Food Sci Nutr.(2019)
- ^Lemuel W. Taylor IVDoes Daily Supplementation of Lactobacillus Acidophilus MPH734, for One Week, Affect Acute (Immediate), Subacute (7 Days), and Post-treatment Discontinuation Lactose Metabolism, Gastrointestinal Symptoms, and Clinical Markers of Inflammation and Safety Compared to a Placebo (LF)(preregistration).(2020-08)
- ^Usai-Satta P, Scarpa M, Oppia F, Cabras FLactose malabsorption and intolerance: What should be the best clinical management?World J Gastrointest Pharmacol Ther.(2012-Jun-06)
- ^Pop Rocks FAQ
- ^Pringles Salt and Vinegar Chips
- ^Fazeli W, Kaczmarek S, Kirschstein M, Santer RA novel mutation within the lactase gene (LCT): the first report of congenital lactase deficiency diagnosed in Central Europe.BMC Gastroenterol.(2015-Jul-28)
- ^Silanikove N, Leitner G, Merin UThe Interrelationships between Lactose Intolerance and the Modern Dairy Industry: Global Perspectives in Evolutional and Historical BackgroundsNutrients.(2015 Aug 31)
- ^Vuorisalo T, Arjamaa O, Vasemägi A, Taavitsainen JP, Tourunen A, Saloniemi IHigh lactose tolerance in North Europeans: a result of migration, not in situ milk consumptionPerspect Biol Med.(2012)
- ^Ajmol Ali, Sung-Je Lee and Kay J. Rutherfurd-MarkwickSports and Exercise SupplementsWhey Proteins: From Milk to Medicine.(2019)
- ^E.A.Foegeding, P.Luck, B.VardhanabhutiSports and Exercise SupplementsEncyclopedia of Dairy Sciences (Second Edition).(2011-04)
- ^Kliegman RM, Sparks JWPerinatal galactose metabolism.J Pediatr.(1985-Dec)
- ^Coelho AI, Berry GT, Rubio-Gozalbo MEGalactose metabolism and health.Curr Opin Clin Nutr Metab Care.(2015-Jul)
- ^Alexander DD, Bylsma LC, Vargas AJ, Cohen SS, Doucette A, Mohamed M, Irvin SR, Miller PE, Watson H, Fryzek JPDairy consumption and CVD: a systematic review and meta-analysisBr J Nutr.(2016 Feb 28)
- Breath Hydrogen - Barillas C, Solomons NWEffective reduction of lactose maldigestion in preschool children by direct addition of beta-galactosidases to milk at mealtimePediatrics.(1987 May)
- Breath Hydrogen - Ibba I, Gilli A, Boi MF, Usai PEffects of exogenous lactase administration on hydrogen breath excretion and intestinal symptoms in patients presenting lactose malabsorption and intoleranceBiomed Res Int.(2014)
- Breath Hydrogen - Corazza GR, Benati G, Sorge M, Strocchi A, Calza G, Gasbarrini Gbeta-Galactosidase from Aspergillus niger in adult lactose malabsorption: a double-blind crossover studyAliment Pharmacol Ther.(1992 Feb)
- Breath Hydrogen - Solomons NW, Guerrero AM, Torun BDietary manipulation of postprandial colonic lactose fermentation: II. Addition of exogenous, microbial beta-galactosidases at mealtimeAm J Clin Nutr.(1985 Feb)
- Breath Hydrogen - Ojetti V, Gigante G, Gabrielli M, Ainora ME, Mannocci A, Lauritano EC, Gasbarrini G, Gasbarrini AThe effect of oral supplementation with Lactobacillus reuteri or tilactase in lactose intolerant patients: randomized trialEur Rev Med Pharmacol Sci.(2010 Mar)
- Breath Hydrogen - de Vrese M, Laue C, Offick B, Soeth E, Repenning F, Thoß A, Schrezenmeir JA combination of acid lactase from Aspergillus oryzae and yogurt bacteria improves lactose digestion in lactose maldigesters synergistically: A randomized, controlled, double-blind cross-over trialClin Nutr.(2015 Jun)
- Breath Hydrogen - Montalto M, Nucera G, Santoro L, Curigliano V, Vastola M, Covino M, Cuoco L, Manna R, Gasbarrini A, Gasbarrini GEffect of exogenous beta-galactosidase in patients with lactose malabsorption and intolerance: a crossover double-blind placebo-controlled studyEur J Clin Nutr.(2005 Apr)
- Breath Hydrogen - Medow MS, Thek KD, Newman LJ, Berezin S, Glassman MS, Schwarz SMBeta-galactosidase tablets in the treatment of lactose intolerance in pediatricsAm J Dis Child.(1990 Nov)
- Breath Hydrogen - Rosado JL, Solomons NW, Lisker R, Bourges HEnzyme replacement therapy for primary adult lactase deficiency. Effective reduction of lactose malabsorption and milk intolerance by direct addition of beta-galactosidase to milk at mealtimeGastroenterology.(1984 Nov)
- Heartburn Symptoms - Cheng AH, Brunser O, Espinoza J, Fones HL, Monckeberg F, Chichester CO, Rand G, Hourigan AGLong-term acceptance of low-lactose milkAm J Clin Nutr.(1979 Oct)