Last Updated: 27 March 2023

Lactase Enzymes For Lactose Intolerance & IBS – Do They Help?

Researched & Written By:
Of all the digestive enzymes on the market, lactase is easily the most common and well-known enzyme available. From supplements to pre-treated dairy products on grocery store shelves, lactase has single-handedly improved the GI woes of countless people struggling with lactose intolerance. In this article, we'll be talking about lactase -- what it is, what it does, proper dosing, and also the underlying mechanisms behind lactose malabsorption, intolerance, and lactose as a trigger for IBS symptoms.
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Table of Contents

What Is Lactase?

Lactase, or β-galactosidase, is an enzyme that helps digest the naturally occurring sugar in milk, known as lactose. It is found in varying amounts in the milk of all mammals, except sea lions, oddly enough.1

When lactase breaks down lactose, it releases two single sugar molecules, called glucose and galactose. Once freed up by lactase, these sugar molecules can then be absorbed by the intestines and used by the body for energy.2

Lactose Malabsorption

What is lactose malabsorption?

Lactose malabsorption is when someone does not make enough lactase to digest the lactose in milk products. This results in undigested lactose making it to the large intestine and being fermented by colonic bacteria, which produce short-chain fatty acids and gasses such as hydrogen, carbon dioxide, and methane.3
Lactose malabsorption occurs when not enough lactase enzymes
Lactose malabsorption is when someone does not make enough lactase to digest the lactose in milk products

What causes lactose malabsorption?

Unless someone is born with the rare genetic condition that prevents them from making lactase, all babies are born with the ability to produce lactase so that they can digest breastmilk.4

However, the ability to produce lactase fades with time for most people. This is referred to as lactose non-persistence, primary lactase deficiency, or primary hypolactasia, and is the most common cause of lactose malabsorption.

Another cause of lactose malabsorption is secondary lactase deficiency, which occurs due to some other gastrointestinal issue that causes bowel damage, like inflammatory bowel disease or gastroenteritis. Lactose malabsorption that results from secondary lactase deficiency is usually reversible and may require a temporary lactose-free diet.5

How can you test for lactose malabsorption?

There are a number of different tests that can be used to diagnose lactose malabsorption.

The most common testing methods are either a lactose hydrogen breath test or lactose tolerance test. These are used regularly in both the clinical and research settings, but unfortunately are less reliable in people with rapid GI transit, which, as we will soon learn, can be symptom induced by lactose malabsorption.4

Other more reliable options include a genetic test or a biopsy, but these are not exactly feasible for most people outside of a research setting.

How common is lactose malabsorption?

Global prevalence of lactose malabsorption is around 68%.

However, the numbers vary significantly between different ethnic and racial groups. For example, the prevalence of lactose malabsorption is as low as 4% in European countries such as Ireland and Denmark, but is almost 100% in some African and Asian countries.

In the United States, prevalence has been found to be around 36%.16

Prevalence of lactose malabsorption in different countries
Prevalence of lactose malabsorption in different countries assessed with all methods - Courtesy of Lancet

Quick Summary

Lactose Intolerance

What is lactose intolerance? How is it different to lactose malabsorption?

Lactose intolerance is a common but very misunderstood condition characterized by a combination of lactose malabsorption and the presence of symptoms when consuming lactose.

These symptoms include bloating, distention, nausea, abdominal pain, diarrhea, and sometimes even constipation.57

Not everyone who has lactose malabsorption experiences symptoms with lactose, therefore would not be considered lactose intolerant.

Can people with lactose intolerance consume any lactose?

Lactose intolerance includes symptoms
Lactose intolerance is a combination of lactose malabsorption and the presence of GI symptoms (e.g. bloating) when consuming lactose foods or drinks

It turns out the amount of lactose those with lactose intolerance can handle before experiencing symptoms varies a lot.

In fact, studies have found that those with lactose intolerance can often tolerate 12 g of lactose, or about a cup of milk, before having any significant digestive issues.38

To help put this into perspective, below is a brief table showing the lactose content of popular foods & drinks.

Lactose Content of Common Sources of Lactose
Lactose Content (grams)
Cow’s Milk (whole, 2%, 1%, skim)
Yogurt, low fat (1 cup)
Ice cream (½ cup)
Cheese (1 oz)
< 1
< 0.5

Lactose intolerance vs IBS

Unless you’re brand new to the IBS world, you may have noticed that the symptoms of lactose intolerance overlap quite a bit with the symptoms used to diagnose IBS. Because of this, being evaluated for lactose malabsorption can be helpful, especially if someone has noticed a consistent pattern between their symptoms and dairy consumption.

It turns out that the risk of having lactose malabsorption is about the same regardless of if you have IBS. However, those with IBS are more likely to be lactose intolerant if they do have lactose malabsorption. 910 We don’t know exactly why this is, but one idea is that it may have to do with the whole issue of IBS patients having increased sensitivity to pain in their gut.9

Studies on IBS patients who think they have lactose intolerance have found that following a lactose-free diet can be effective at decreasing symptom scores, however these beneficial results seemed to occur whether or not the person actually had lactose malabsorption.11

This suggests that for some people, there may be some other component in milk besides lactose that is causing the IBS symptoms.

Dealing with lactose intolerance
People with IBS are more likely to be lactose intolerant if they do have lactose malabsorption

How to deal with lactose intolerance

Consulting your doctor should be the first step in diagnosing lactose intolerance. They can help you decide if getting tested for lactose malabsorption is right for you.

If the test does come back positive, it is recommended that each person determine what their individual lactose tolerance threshold is instead of swearing off dairy products forever.12 This means doing a lactose-free diet for a period of time (maybe 2-4 weeks), monitoring for symptom relief, then slowly challenging your body to see how much lactose it can handle before you start to have symptoms5.

How much you can tolerate will depend on how much lactase your body still makes and the foods you are eating the lactose with, as well as your gut microbiota and GI tract sensitivity.13 Milk does provide us with a variety of important nutrients, especially calcium, so ideally you can find a tolerance level that doesn’t require you to cut lactose out completely. 

You can also consider using lactase enzymes to help digest the lactose in foods and drinks.  We will discuss this idea in-depth in the next section.

Quick Summary

Lactase Enzymes

Food & drinks with lactase vs lactase enzyme supplements

Once you find your individual lactose tolerance level, you can try using lactase to see if it can help further increase your tolerance. This is done by either:

  1. Buying products where the lactose has already been completely broken down, by pre-treating lactose-containing liquids with liquid lactase drops.
  2. Taking a lactase tablet or pill supplement when consuming foods that have more lactose in them than you can tolerate. 

Can lactase enzymes help with lactose intolerance?

The literature on lactose intolerance in general does seem to show that lactase helps to some extent in some people. 14151617 How well it works appears to depend on several factors, including:

  • The amount of lactase used 
  • The source of the lactase (fungal vs yeast)
  • When the lactase was taken in relation to the lactose-containing product
  • Gastrointestinal motility and acidity (pH)
  • The foods you are eating along with the lactase and lactose
  • If the lactose was even the main cause of the symptoms to begin with

Has lactase been shown to help with IBS?

The research on the efficacy of lactase supplementation for IBS specifically is sadly very sparse, and we could only find one study that looked directly at supplementation with this enzyme in IBS patients. In this one very small IBS study, lactase did not result in significant symptom improvements.18

Lactase enzymes for lactose intolerance and IBS
Lactase enzymes may help with lactose intolerance, but it depends on several key factors

The takeaway from these studies

While we do have evidence to show that supplementing with lactase can help relieve symptoms in those with lactose intolerance, because of all the factors that can affect how well it works, figuring out what works for you is inevitably going to be a bit of a trial and error situation.  In the final section, we’ll look at different options for doing this.

Quick Summary

How To Take Lactase Enzymes

Lactose-free products vs lactase enzyme supplement

When drinking milk, pre-hydrolyzed/lactose-free milk will likely be more effective than taking lactase tablets. 11 However, these kinds of specialized milk products may not always be a realistic option in every situation. In cases where you don’t have access to a lactose-free version of the dairy product you want to consume, you can try taking the lactase enzyme supplement instead. 

How much to take (dosing) - for supplements

Doses around 6000-9000 FCC lactase units have been studied and shown to be effective, so this may be a good starting point.16

Most lactase brands available in the United States, such as Lactaid, contain 9000 FCC lactase units per tablet.

You should follow the manufacturer’s instructions, which usually recommend starting out by taking 1 tablet with your first bite of food.19

Lactase safety and other tips

Lactaid specifically is made from a yeast called Kluyveromyces lactis and is on the Food and Drug Administration’s (FDA)  “Generally Recognized As Safe” (GRAS) list.20 There are other sources of lactase that come from fungi, but they may not be as easy to find as Lactaid. For example, there’s a German brand called Lactrase that is made from the fungus, Aspergillus oryzae. S

If you find that lactase enzymes aren’t helping you, it might be worth trying a different brand, as it’s possible the additives in that particular supplement are not agreeing with you. For example, several of the lactase brands available contain sugar alcohols, such as mannitol and sorbitol, which are a type of FODMAP. FODMAPs can be a source of increased IBS symptoms in some people, so you may want to try a brand of lactase that doesn’t contain these ingredients. 

Lastly, as always check, with your doctor before starting and stopping a supplement of any kind, as it may not be appropriate for everyone.

    • Those with diabetes should be aware that there may be changes in blood sugar due to the increased availability of simple sugars as a result of improved lactose digestion.
    • Those with a rare genetic condition called galactosemia may also need to avoid this enzyme, as it will increase the amount of galactose that needs to be digested.
    • Anyone with mold allergies should also be extra cautious, since lactase is sometimes sourced from certain types of fungus.21

Quick Summary

Summary & Verdict

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Which Foods Really Trigger Your IBS?

Discover exactly which foods you should and shouldn’t eat using our IBS Food Journal.

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  9. Varjú P, Gede N, Szakács Z, Hegyi P, Cazacu IM, Pécsi D, Fábián A, Szepes Z, Vincze Á, Tenk J, Balaskó M, Rumbus Z, Garami A, Csupor D, Czimmer J. Lactose intolerance but not lactose maldigestion is more frequent in patients with irritable bowel syndrome than in healthy controls: A meta-analysis. Neurogastroenterol Motil. 2019 May;31(5):e13527. doi: 10.1111/nmo.13527. Epub 2018 Dec 17. PMID: 30560578; PMCID: PMC7379306.

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  11. Krieger-Grübel C, Hutter S, Hiestand M, Brenner I, Güsewell S, Borovicka J. Treatment efficacy of a low FODMAP diet compared to a low lactose diet in IBS patients: A randomized, cross-over designed study. Clin Nutr ESPEN. 2020 Dec;40:83-89. doi: 10.1016/j.clnesp.2020.09.020. Epub 2020 Oct 6. PMID: 33183577.

  12. Montalto M, Curigliano V, Santoro L, Vastola M, Cammarota G, Manna R, Gasbarrini A, Gasbarrini G. Management and treatment of lactose malabsorption. World J Gastroenterol. 2006 Jan 14;12(2):187-91. doi: 10.3748/wjg.v12.i2.187. PMID: 16482616; PMCID: PMC4066025.

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  19. LACTAID Original Strength Lactase Enzyme Supplement Caplets

  20. CFR – Code of Federal Regulations Title 21. Code of Federal Regulations, Title 21, Volume 3, CITE: 21CFR184

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