Lactase enzyme supplements

What it is

Lactase is the enzyme that splits milk sugar (lactose) into glucose and galactose in the small intestine. Supplements are tablets or drops of lactase, made from microbes such as the yeast Kluyveromyces lactis or moulds such as Aspergillus, taken with dairy or added to milk.

What the research says

Lactase supplements reduce the hydrogen gas that signals undigested lactose and modestly reduce symptoms in trials, but the effects are modest. A 2010 systematic review found insufficient evidence that lactose-reduced products and lactase reduce symptoms compared with lactose at doses of up to 12 g, which most people with lactose intolerance can tolerate anyway, though two of five trials using larger lactose doses found symptom reductions. Rare allergic reactions, including anaphylaxis, have been reported.

Evidence grade: Limited evidence.

What goes wrong

A 38-year-old woman had an IgE-mediated anaphylactic reaction to a lactase enzyme tablet, reported as the first documented case. (Source 1)

• Case report, Very low certainty.
• Size: 1 patient.
• Who: Adult woman with self-diagnosed lactose intolerance.
• How long: single exposure.
• Result: Orbital swelling, shortness of breath, throat constriction; skin prick test positive to lactase.
• Funding: not stated.

bilateral orbital swelling, shortness of breath, and throat constriction after oral ingestion of a supplemental lactase enzyme tablet.

What the evidence supports

In a double-blind placebo-controlled crossover trial in 30 lactose malabsorbers with intolerance, lactase from Kluyveromyces lactis added to milk reduced breath hydrogen and symptoms versus placebo. (Source 2)

• Randomized trial, Low certainty.
• Size: 30 participants.
• Who: Adults aged 18-65 with lactose malabsorption and intolerance, university hospital, Italy.
• How long: Three single-test breath tests with 400 ml milk.
• Result: Both enzyme conditions reduced breath hydrogen and symptoms vs placebo (p<0.001); adding 10 h before was better for symptoms than 5 min before (p=0.03)
• Funding: not stated in fetched text.

The lactase obtained from K. lactis can represent a valid therapeutic strategy, with objective and subjective efficacy and without side effects

A 2019 review in Gut concluded lactase tablets improve lactose digestion and symptoms, but the effects are modest. (Source 3)

• Systematic review, Low certainty.
• Size: not stated.
• Who: People with lactose malabsorption and intolerance.
• How long: various.
• Result: Example: 18% overall reduction of symptoms.
• Funding: not stated.

Lactase supplementation by tablets improves both lactose digestion (reduced H2 production) and symptoms although the effects are modest (eg, 18% with overall reduction of symptoms).

What the evidence does not support

A systematic review for the US AHRQ/NIH consensus found insufficient evidence that lactose-reduced or hydrolysed formulations and lactase supplements reduce symptoms compared with lactose; none of four trials with control doses of up to 12 g lactose found a significant symptom improvement. (Source 4)

• Systematic review, Low certainty.
• Size: not stated in fetched text.
• Who: Adults and children with lactose intolerance or malabsorption.
• How long: various.
• Result: None of four trials with controls of up to 12 g lactose found significant improvement in overall symptoms.
• Funding: US government (AHRQ)

Limit of this finding: This conclusion covers lactose-reduced and hydrolysed formulations together with lactase (28 trials), not lactase alone. The same review reports that two of five trials found significant symptom reductions when the comparison group was given more than 12 g of lactose, so it does not show that lactase never helps.

There was insufficient evidence of effectiveness in reducing symptoms of lactose intolerance (when compared with lactose).

Where the evidence is mixed

Most people with presumed lactose intolerance can tolerate 12-15 g of lactose, which limits how much a supplement can add. (Source 4)

• Systematic review, Low certainty.
• Size: not stated.
• Who: People with presumed lactose intolerance.
• How long: various.
• Result: Tolerance of 12 g to 15 g lactose.
• Funding: US government (AHRQ)

Most individuals with presumed lactose intolerance or malabsorption can tolerate 12g to 15g of lactose.

The same systematic review reported that two of five trials found significant reductions in overall symptoms when the comparison group received more than 12 g of lactose. (Source 5)

• Systematic review, Low certainty.
• Size: 5 trials with controls given more than 12 g lactose.
• Who: People with lactose intolerance or malabsorption.
• How long: various.
• Result: 2 of 5 trials: significant reduction in overall symptoms.
• Funding: US government (AHRQ)

Two of five trials reported significant reductions in overall symptoms compared with control participants given more than 12g of lactose.

Where the research disagrees

Whether lactase supplements meaningfully reduce symptoms

• Misselwitz et al. (Gut, 2019), narrative review of trials: "Lactase supplementation by tablets improves both lactose digestion (reduced H2 production) and symptoms although the effects are modest" (Source 3)
• Shaukat et al. (Annals of Internal Medicine, 2010), systematic review: "There was insufficient evidence of effectiveness in reducing symptoms of lactose intolerance (when compared with lactose)." (Source 4)

How much

• Reference intake: No reference intake exists; lactase supplements are an enzyme product, not a nutrient. The US NIDDK describes them as tablets taken before dairy or drops added to milk. (Source 6)
• Upper limit: No upper limit has been set by any body we found for lactase supplements. (Source 6)
• Studied: Trial: lactase from K. lactis, 3000 IU added to 400 ml milk 10 hours before, or 6000 IU added 5 minutes before drinking, versus placebo. (Source 2)

A common belief, and what the research shows

The belief: People with lactose intolerance must take lactase or avoid all dairy.

What the research shows: A systematic review found "Most individuals with presumed lactose intolerance or malabsorption can tolerate 12g to 15g of lactose." and that for lactase supplements "There was insufficient evidence of effectiveness in reducing symptoms of lactose intolerance (when compared with lactose)."

Questions and answers

What is it?

Lactase is the enzyme that splits lactose, the sugar in milk, into glucose and galactose. Supplements supply the enzyme as tablets or drops. (Source 6)

What does it do in the body?

In the gut, lactase breaks lactose down so it can be absorbed. Supplement lactase does the same job for the dairy it is taken with, reducing hydrogen gas production and symptoms modestly in trials. (Source 3)

Is it good or bad for you?

For people with lactose intolerance, trials show modest benefit, though the evidence is low quality and one systematic review found it insufficient. Rarely, the enzyme itself has caused allergic reactions including anaphylaxis. (Source 1)

How do you get more of it?

Studied approaches are lactase tablets taken with dairy, lactase drops added to milk, and lactase added to milk hours in advance. The body's own lactase production is set largely by genes and gut health rather than by behaviour. (Source 6)

If it is harmful, what reduces it?

Does not apply: lactase is not harmful. The exception is the rare person allergic to the supplement enzyme, who in case reports was advised to avoid lactase products. (Source 1)

Why might someone be low in it or missing it?

In most of the world's population, lactase activity falls during childhood, which is genetically determined. Lactase can also be lost temporarily or longer-term when the small bowel is damaged, for example by gastroenteritis, inflammatory bowel disease or coeliac disease. (Source 7)

Which whole foods contain it or feed it?

Foods do not supply lactase in a studied way, but some dairy foods contain less lactose: yoghurt has about half the lactose of milk and long-ripened cheese has little. (Source 8)

What happens if you do not have it?

Without enough lactase, lactose passes undigested to the colon. Some people then get abdominal pain, bloating and diarrhoea after dairy, which is lactose intolerance; how likely this is depends on dose, enzyme level and gut microbes. (Source 9)

How can you test for it?

The hydrogen breath test is the usual test: a rise of 20 ppm or more within 3 hours after lactose indicates malabsorption, but some people's gut bacteria produce no hydrogen, giving false negatives. Genetic tests detect genetic lactase non-persistence but are less reliable in people of African or Asian heritage and miss secondary causes. (Source 10)

References

1. Allergy, Asthma & Clinical Immunology. Anaphylaxis to supplemental oral lactase enzyme. 2016. PMID 27999602, DOI 10.1186/s13223-016-0171-8. Read the source
2. European Journal of Clinical Nutrition. Effect of exogenous beta-galactosidase in patients with lactose malabsorption and intolerance: a crossover double-blind placebo-controlled study. 2005. PMID 15674309, DOI 10.1038/sj.ejcn.1602098. Read the source
3. Gut. Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. 2019. PMID 31427404, DOI 10.1136/gutjnl-2019-318404. Read the source
4. Database of Abstracts of Reviews of Effects (NCBI Bookshelf). Systematic review: effective management strategies for lactose intolerance (DARE structured abstract of Shaukat et al., Ann Intern Med 2010;152:797-803). 2010. PMID 20404262, DOI 10.7326/0003-4819-152-12-201006150-00241. Read the source
5. Database of Abstracts of Reviews of Effects (NCBI Bookshelf). Systematic review: effective management strategies for lactose intolerance (DARE structured abstract of Shaukat et al., Ann Intern Med 2010;152:797-803). 2010. PMID 20404262, DOI 10.7326/0003-4819-152-12-201006150-00241. Read the source
6. National Institute of Diabetes and Digestive and Kidney Diseases (NIH). Treatment for Lactose Intolerance. not stated. Read the source
7. Gut. Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. 2019. PMID 31427404, DOI 10.1136/gutjnl-2019-318404. Read the source
8. Gut. Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. 2019. PMID 31427404, DOI 10.1136/gutjnl-2019-318404. Read the source
9. Gut. Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. 2019. PMID 31427404, DOI 10.1136/gutjnl-2019-318404. Read the source
10. Gut. Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. 2019. PMID 31427404, DOI 10.1136/gutjnl-2019-318404. Read the source