We use essential cookies (authentication, your saved goals/stack) by default. With your permission we’ll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Lct5.5
Lactase Research
Too few graded studies
15 peer-reviewed studies
What the evidence says
Too few graded studies
Lactase doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from medium-quality meta-analyses and randomised trials published 1992–2024 with a typical study size of 47 participants.
Based on 15 studies · 1 meta-analysis · 10 RCTs · 962 total participants
Confidence
Moderate confidence
By outcome
Lactose intolerance & digestionFewer bloating, pain and gas symptoms and lower breath hydrogen when eating dairy, in people with confirmed lactose malabsorption. Not expected to help digestion in people who digest lactose normally. · Same meal
Too few graded studies13 studies
Safety profile
Too few graded studies3 studies
Infant colic & crying
Too few graded studies1 study
Steady research
3 studies in the last 5 years · Latest meta-analysis: 2024
199220082024
1Systematic ReviewCited 132×2010
In plain English: Most individuals with presumed lactose intolerance or malabsorption can tolerate 12 to 15 g of lactose.
Shaukat A, Levitt MD, Taylor BC, MacDonald R, Shamliyan TA, Kane RL, Wilt TJ · Annals of Internal Medicine (2010)
36 randomised trials met the inclusion criteria, 26 of them on lactase- or lactose-hydrolysed milk supplements, lactose-reduced milk, or tolerable doses of lactose.
Moderate-quality evidence indicated that 12 to 15 g of lactose (about 1 cup of milk) is well tolerated by most adults.
Evidence was insufficient that lactose-reduced milk (0 to 2 g lactose) reduces symptoms compared with more than 12 g, and evidence for probiotics and colonic adaptation was also insufficient.
In plain English: While individual trials have shown some promise, the overall evidence for the efficacy of lactase supplementation in treating infant colic remain inconclusive.
Kozłowska-Jalowska A, Stróżyk A, Horvath A, Szajewska H · Journal of Pediatric Gastroenterology and Nutrition (2024)
Five randomised trials with 391 infants under 6 months old with colic were included.
Three trials reported less crying, one of them only in the subgroup that complied with treatment.
Pooling two trials found no difference from placebo in crying duration or fussing time over 1 week of lactase (crying: mean difference -17.66 min/day, 95% CI -60.8 to 25.5).
In plain English: Lactase was superior to placebo in Booster Alpha (0.190; 95% CI: 0.102, 0.365; P < 0.001) but not Booster Omega (0.493; 95% CI: 0.210, 1.156; P = 0.102).
Rasinkangas P, Forssten SD, Marttinen M, Ibarra A, Bothe G, Junnila J, Uebelhack R, Donazzolo Y, Ouwehand AC · The American Journal of Clinical Nutrition (2022)
Two crossover trials in people with lactose intolerance compared a probiotic, 4662 FCC units of lactase, and placebo taken with a lactose challenge, with 1-week washouts. The abstract does not state the number of participants.
Lactase reduced breath hydrogen (incremental AUC) more than placebo in the first trial but not in the second, where the difference was not significant (P = 0.102).
In the first trial lactase lowered the odds of abdominal pain (0.32, P = 0.036) and flatulence (0.25, P = 0.007) compared with placebo.
In plain English: The combined administration of freeze-dried yogurt cultures and acid lactase increases lactose digestion more than either freeze-dried yogurt cultures or acid lactase alone, and more lactose malabsorbers benefited from this effect.
de Vrese M, Laue C, Offick B, Soeth E, Repenning F, Thoß A, Schrezenmeir J · Clinical Nutrition (2015)
Randomised, placebo-controlled, double-blind, 5-arm crossover trial in 24 lactose malabsorbers given 12.5 g of lactose.
Compared with placebo, peak hydrogen exhalation fell by 29% and 33% with 3300 and 9000 FCC units of Aspergillus oryzae acid lactase, by 27% with yogurt culture, and by 46% with 3300 FCC units of lactase plus yogurt culture (p < 0.001).
The higher lactase dose significantly reduced flatulence, and the combination reduced abdominal pain.
In plain English: Our study shows that in lactose malabsorbers with intolerance, the lactase obtained from K. lactis can represent a valid therapeutic strategy, with objective and subjective efficacy and without side effects.
Montalto M, Nucera G, Santoro L, Curigliano V, Vastola M, Covino M, Cuoco L, Manna R, Gasbarrini A, Gasbarrini G · European Journal of Clinical Nutrition (2005)
30 adult lactose malabsorbers with intolerance each had three breath tests on 400 ml of milk in random order: 3000 units of Kluyveromyces lactis lactase added 10 hours before drinking, 6000 units added 5 minutes before, or placebo.
Both lactase conditions lowered peak breath hydrogen (about 12 and 14 ppm vs 51 ppm on placebo) and cumulative hydrogen excretion (P < 0.001).
Both lowered the symptom score compared with placebo (P < 0.001), and adding the enzyme 10 hours ahead gave a lower symptom score than adding it 5 minutes ahead (P = 0.03).
In plain English: In lactose intolerants, tilactase strongly improves both LBT results and gastrointestinal symptoms after lactose ingestion with respect to placebo.
Ojetti V, Gigante G, Gabrielli M, Ainora ME, Mannocci A, Lauritano EC, Gasbarrini G, Gasbarrini A · European Review for Medical and Pharmacological Sciences (2010)
60 lactose-intolerant patients were randomised to tilactase taken 15 minutes before a lactose breath test, placebo, or Lactobacillus reuteri twice daily for 10 days beforehand (20 per group).
Both tilactase and L. reuteri normalised the breath test more often than placebo, and both lowered peak hydrogen and symptom scores compared with placebo (p < 0.0001).
Tilactase was significantly more effective than L. reuteri at normalising the breath test (p < 0.01) and at reducing peak hydrogen and symptom scores.
7CrossoverCited 10×n=47 · small study2021
In plain English: Reduction in cumulative hydrogen breath level over 180 min was 55% when patients received lactase compared to placebo.
Baijal R, Tandon RK · JGH Open (2021)
Randomised, double-blind, placebo-controlled crossover trial of chewable lactase tablets in 47 adults with breath-test-confirmed lactose intolerance, with a 1-week washout.
Clinical symptoms, the mean clinical score and mean hydrogen breath levels improved with lactase compared with placebo (P < 0.05).
Cumulative breath hydrogen over 180 minutes was 55% lower with lactase than with placebo.
In plain English: The 50-g lactose dose appeared to overwhelm the ability of either 3000 or 6000 IU of beta-gal to assist significantly with lactose digestion.
Lin MY, Dipalma JA, Martini MC, Gross CJ, Harlander SK, Savaiano DA · Digestive Diseases and Sciences (1993)
Three lactase preparations (soft gel, caplet and chewable) and placebo were given to lactose maldigesters with 20 g or 50 g of lactose. The abstract does not state the number of participants.
With milk containing 20 g of lactose, all enzyme preparations sharply reduced peak and total breath hydrogen, and about 6000 units reduced total hydrogen more than about 3000 units (P < 0.05). Symptoms were less severe with all products (P < 0.05).
With 50 g of lactose in water, hydrogen production was only modestly and not significantly reduced, and symptom scores did not differ from control.
Multicentre, randomised, single-blind non-inferiority trial in 129 adults with breath-test-confirmed hypolactasia comparing two lactase tablet products, one tablet three times a day for 42 days. There was no placebo arm.
Exhaled hydrogen 90 minutes after the last dose on day 42 was 17 ppm with the test product and 34 ppm with the reference product (difference -17 ppm, 95% CI -31.03 to -3.17), meeting the non-inferiority margin.
Tolerability was excellent in both groups, with no serious adverse events related to treatment.
In plain English: Single doses of a chewable lactase tablet reduced the concentration of expired hydrogen and symptoms of lactose intolerance after a lactose challenge.
Randomised, double-blind, placebo-controlled crossover trial: three chewable lactase tablets (9900 FCC units in total) or placebo with a 50 g lactose challenge. 24 subjects completed the study.
Maximum mean breath hydrogen was significantly lower after lactase than after placebo, and hydrogen AUC was lower with lactase in 21 of 24 subjects.
Plasma glucose did not differ significantly between treatments.
11CrossoverCited 15×n=16 · very small study1992
In plain English: This study demonstrates that enzyme replacement therapy, with beta-galactosidases obtained from Aspergillus niger, is effective in decreasing lactose malabsorption and its consequent intolerance in adult subjects with lactase deficiency.
Corazza GR, Benati G, Sorge M, Strocchi A, Calza G, Gasbarrini G · Alimentary Pharmacology & Therapeutics (1992)
Double-blind, placebo-controlled crossover study in 16 adults with lactose malabsorption and intolerance, using Aspergillus niger lactase added to 400 ml of milk.
Compared with placebo, lactase-treated milk significantly reduced maximum breath hydrogen (P < 0.01) and cumulative hydrogen excretion (P < 0.005).
The cumulative gastrointestinal intolerance index was also significantly lower (P < 0.005).
In plain English: A single oral administration of tilactase is highly effective in decreasing symptoms and hydrogen excretion of hypolactasia assessed by lactose H(2)-breath test.
Portincasa P, Di Ciaula A, Vacca M, Montelli R, Wang DQ, Palasciano G · European Journal of Clinical Investigation (2008)
134 adults with hypolactasia had a lactose breath test with placebo and then a second test with a low (6750 U) or standard (11,250 U) dose of tilactase, an Aspergillus oryzae lactase. The order was fixed, and the abstract does not describe randomisation or blinding.
Integrated breath hydrogen fell by 74 to 75% with the low dose and 87 to 88% with the standard dose.
In the 109 subjects with symptoms, the total symptom score fell by 76% with the low dose and 88% with the standard dose (P < 0.0001).
In plain English: In lactose-intolerant subjects, the available lactase preparations differ in their ability to improve both breath hydrogen excretion and symptoms.
Ramirez FC, Lee K, Graham DY · The American Journal of Gastroenterology (1994)
Randomised, placebo-controlled comparison of three commercial lactase products in 10 lactose-intolerant volunteers challenged with ice cream containing 18 g of lactose.
Only one of the three products reduced breath hydrogen (p < 0.05), and that product did not reduce symptoms.
A second product reduced pain, bloating and total symptom scores (p < 0.05), and the third reduced only pain (p < 0.05), without either lowering breath hydrogen.
14Open-LabelCited 22×n=96 · small study2014
In plain English: The response to oral administration of Beta-Galactosidase in patients with symptoms of lactose malabsorption presents a significant variability.
Ibba I, Gilli A, Boi MF, Usai P · BioMed Research International (2014)
96 consecutive patients with a positive lactose breath test, all with the lactase non-persistence genotype, repeated the test after a standard oral dose of lactase. There was no placebo group.
The breath test became negative in 21.88% of patients.
In 17.71% it stayed positive but with a significantly lower hydrogen peak than at baseline.