What to Know About the Lactase Enzyme

Lactase is a digestive enzyme involved in the breakdown of lactose, a sugar found in milk and other dairy products. People with lactose intolerance cannot produce enough lactase on their own.

A lack of lactase often causes uncomfortable side effects like diarrhea, bloating, stomach pain, and nausea after consuming dairy. Taking lactase supplements may reduce or prevent many of these symptoms for people with lactase deficiency, lactose intolerance, or other conditions affecting the digestion of lactose.

This article will look at the science behind the uses of lactase, its side effects, and precautions. It will also cover dosage and what to look for when choosing a lactase supplement.

Uses of Lactase

During digestion, lactase produced in the lining of the small intestine splits lactose into smaller sugar molecules (known as glucose and galactose) for absorption. Lactase supplements are mostly used by people who have difficulty digesting lactose found in dairy products.

People with lactose intolerance, lactase deficiency, or sensitivity to lactose may benefit from using lactase enzymes. However, it's important to note that lactase supplements would not be useful for someone with a milk protein allergy because it's not the same as lactose intolerance.

Although lactase is mostly used to prevent symptoms of lactose intolerance, it has also been studied for its role in bone health.

Lactose Intolerance

While lactase enzymes cannot cure lactose intolerance, they may be able to reduce or eliminate symptoms associated with eating dairy. However, even though scientists agree that lactase supplements are safe, there has not always been a consensus on how well they work.

A 2014 study reported significant variability in response to lactase supplementation. Of the 96 adults given a lactase supplement, 22% showed complete normalization on a hydrogen breath test used to evaluate lactose intolerance, while 18% were fully non-responsive.

A pair of studies from 2020 and 2021 further indicated that lactase enzyme supplements appear to be an appropriate treatment option for those with lactose intolerance.

It should be noted that many people with lactose intolerance have additional food sensitivities or allergies. For example, people with irritable bowel syndrome (IBS) may find it best to avoid food containing lactose and other aggravating ingredients.

Essentially, other factors may contribute to being unable to metabolize lactose. Despite the positive results for lactase enzymes, some people may need to use other treatment options for their lactose intolerance. Work with your healthcare provider to find the best option for you.

Bone Health

Lactase supplements cannot improve bone health directly. However, lactase can help people who are lactose intolerant eat more dairy without side effects. According to a 2019 study, avoiding or cutting back on dairy due to lactose intolerance can put people at risk for bone loss and fractures (broken bones).

This is because they are not getting enough calcium. Eating enough calcium can help build and maintain healthy bones while reducing the risk of bone loss and osteoporosis.

Results on whether lactose intolerance leads to osteoporosis have been conflicting. It should be noted that neither lactose intolerance nor lactase deficiency significantly affects the ability to absorb calcium.

People who have difficulty digesting lactose can still absorb calcium from dairy products. It is recommended that everyone—including those with lactose intolerance—consume three servings of dairy per day. Lactase supplements may be able to help you get there.

Lactase Deficiency

According to a 2019 study, around 70% of the world's population is lactase deficient, with the highest prevalence among people of East Asian, West African, Arab, Jewish, Greek, or Italian descent.

However, not everyone deficient in lactase has lactose intolerance. A deficiency can mean levels of lactase are lower than normal, but still present. And lactose intolerance only occurs when symptoms like bloating, diarrhea, and abdominal pain appear.

Lactase deficiency can appear over time as you age. It can also be diagnosed during childhood or even at birth.

What Causes a Lactase Deficiency?

Lactase deficiencies can be genetic, but this is not always the case. There are four possible causes of lactase deficiency, with two being genetics-related.

Two genetic causes of lactase deficiency include:

• Lactase non-persistence: In a person with lactase non-persistence, their lactase levels will get lower over time, causing a gradual decrease.
• Congenital lactase deficiency (CLD): With CLD, the small intestines never make enough lactase from birth. It is a rare disorder, diagnosed in newborns, that can lead to malnutrition.

There are also two non-genetic causes of lactase deficiency:

• Injury to the small intestine: In this case, inflammation, infection, or a disease affecting the intestines, like Crohn's disease, can lead to a decrease in the lactase enzyme.
• Premature birth: Some babies born early have underdeveloped small intestines that have not had time to produce lactase efficiently. The baby may grow out of this type of lactase deficiency over time.

How Do I Know if I Have a Lactase Deficiency?

A lactase deficiency may cause various symptoms alerting you to a problem.

The severity of your deficiency and the underlying cause may worsen symptoms. For example, a person with lactose non-persistence may tolerate some amounts and types of dairy products without experiencing any symptoms.

However, if you have any of the following symptoms within a few hours after consuming dairy, then it may be time to get an official diagnosis:

• Bloating
• Gas
• Diarrhea
• Nausea
• Stomach pain
• Vomiting

To officially diagnose lactose intolerance, a healthcare provider may want to perform various tests, including a physical exam and a hydrogen breath test.

You may risk worsening symptoms if a lactase deficiency or lactose intolerance goes undiagnosed. Excessive diarrhea and vomiting can lead to dehydration, while gas and stomach pain can be highly uncomfortable.

Speak with a healthcare provider if you think you have a lactase deficiency.

How to Take Lactase

Lactase doses can vary from 3,000 to 6,000 international units (IU) taken immediately before a meal containing dairy. You may need a lactase dose outside of this range.

Lactase supplement dosage can vary and may depend on a few factors, such as:

• The severity of your symptoms
• The amount of lactose you plan to consume
• Source and brand of lactase supplements

For example, Lactaid supplements (a lactase supplement brand) contain 9,000 units of the active enzyme, while Lacdigest (another lactase supplement brand) contains just 2,250 units.

It may be helpful to start at a low dose and gradually increase it until you achieve the desired control. There is no evidence suggesting lactase can be toxic if too much is taken and side effects are unlikely, but your healthcare provider should be able to assist you in finding the correct lactase dose.

When Should I Take Lactase?

Be sure to follow the directions when taking lactase supplements. It is recommended to take a lactase supplement before consuming dairy products.

It may be necessary to take an additional dose of lactase if you plan to eat over a period longer than 20 to 30 minutes (say, at a picnic or banquet).

Does Lactase Have Side Effects?

Lactase supplements are generally considered safe and well-tolerated by most people. If your healthcare provider has recommended that you take lactase supplements, they most likely believe the benefits outweigh any potential risks when taken as directed.

Side effects of taking lactase supplements are not common. Although rare, lactase supplements can trigger an allergic reaction.

There have been a few cases of lactase causing a severe reaction that requires emergency care. In one of these reported cases, a 48-year-old person experienced a severe, whole-body allergy known as anaphylaxis after taking lactase.

If left untreated, anaphylaxis can lead to shock, coma, respiratory or heart failure, and death. Lactase supplements are generally considered safe and well-tolerated by most people.

Precautions

It's important to speak with a healthcare provider before starting lactase supplements. Lactase supplements may not be suitable for certain people in different life stages, with various health conditions, and those with allergies.

Do not take lactase supplements if you are allergic to any of the active or inactive ingredients.

It is best for people who are pregnant or nursing to speak with a healthcare provider before using lactase supplements. Evidence on whether lactase is safe for these populations is limited, so your healthcare provider may advise against taking it.

Similar Supplements

You may be able to use other supplements in place of or in addition to lactase enzymes.

Supplements similar to lactase used by some to treat lactose intolerance include:

• Probiotics: Various studies have shown that probiotics can help treat lactose intolerance. Probiotics are thought to help in different ways, including decreasing diarrhea, expressing lactase, and changing the pH of your gut.
• Prebiotics: Evidence of prebiotics for treating lactose intolerance is not as strong as probiotics. However, prebiotics may still be a viable option. In one study, prebiotics improved lactose intolerance symptoms and digestion of lactose.
• Fermented milk: Drinking fermented milk is associated with increased lactase enzyme activity in the small intestine. Choosing fermented dairy products over nonfermented ones is thought to potentially reduce symptoms of lactose intolerance.

You may be able to use these supplements and other lifestyle changes to treat symptoms of lactose intolerance or lactase deficiency. Collaborate with your healthcare provider to find the best treatment plan for you.

Sources of Lactase and What to Look For

Lactase is not widely found in food. Typically, your body makes lactase for you. But if you cannot make enough lactase, you may need to use a supplement.

Lactase supplements are sold in many forms, including: 

• Capsules
• Chewables
• Powders or drops that you can add to regular milk products

Widely available for purchase online, lactase supplements can also be found in various grocery stores, drugstores, and shops specializing in dietary supplements. You do not need a prescription to buy lactase supplements.

Lactase is not derived from dairy, so taking supplements is not a concern if you are vegan. However, the coating that makes up some capsules may be made of animal-derived gelatin. If this is a concern, look for products labeled as vegan.

Summary

Lactase is a digestive enzyme made by the body to break down the lactose found in dairy products. However, many people are unable to produce enough lactase and may need to use a supplement when consuming dairy.

Lactase supplements are generally recognized as safe and come with few potential side effects, precautions, or interactions. Your dose of lactase supplements may depend on the severity of your lactose intolerance symptoms, your dairy intake, and the brand of supplement.

If you are thinking of starting a lactase enzyme supplement, speak with a healthcare provider to find the best dosage and brand for you.