Lactose Intolerance: Relieve it with Lactase Enzymes!

Lactose Intolerance: Relieve it with Lactase Enzymes!

In this post, we’re going to talk about lactose, a molecule feared by many as a result of the well-known intolerance.

What is lactose?

Lactose is a disaccharide, the union of two monosaccharides (galactose+glucose) through a glycosidic link β-1,4, that is, it is a sugar present only in mammalian milk and, exceptionally, in reduced quantities in exotic plants that are not part of the environment of developed societies. So:

Lactose is the sugar from the milk.

Strucuture galactose

Chemical structure of galactose and glucose.

What is its function?

Lactose, by itself, has no function, it is simply a component of the milk naturally produced by lactating mammals.

Once its monosaccharides are absorbed, however, it does have a function:

  • Glucose: Mainly energy function, and regulating in a secondary way.
  • Galactose: Energy and plastic function.

Galactose is a basic substrate necessary for the biosynthesis of various molecules in the body. It is an important constituent of:

  • Complex polysaccharides, which are part of the cells’ glucoconjugates.
  • Key elements of the immunological determinants.
  • Hormones.
  • Structures of the cell membrane.
  • Endogenous lectins.
  • Other glycoproteins.
  • Galactolipids, important structural elements of the central nervous system.

Flynn (2016).

We could say that the functions of lactose are those attributed to galactose, since glucose is widely present in many hydrocarbon foods available in the common diets from around the world.

How is lactose digested?

Lactose is a disaccharide, and these structures do not have the capacity to cross the barriers of our intestine. To do so, they have to be simplified into the monosaccharides that compose it, in this case glucose+galactose, and we need something that breaks the glucosidic link to release it.

Responsible for this is lactase (β-galactosidase).

Hydrolysis lactose

Graphic representation of hydrolysis and intestinal absorption of lactose.

Lactase is found in the microvilli of the intestinal brush, especially in the central part of the jejunum, in a lactase/floricin hydrolase complex, which can also hydrolyse other dietary carbohydrates.

Both glucose and galactose are absorbed by the same type of sodium-dependent (co-)carriers, the SGLT-1. You can read more about it here.

Once absorbed, they go into the blood where they can be used for the previously described functions.

Why lactose intolerance?

Lactose has a differentiating characteristic:

When we are born, we are able to digest it completely and perfectly (except in cases of congenital alacthasia), as breast milk, which contains lactose, is our main nutritional support.

Once we’ve passed the lactation phase the ability to digest lactose tends to decrease significantly in many people (with higher or lower prevalence depending on geographical location).


Lactose (in)tolerance phenotypes.

Someone not able to cope well with lactose consumption is considered lactose intolerant.

What to do if I’m intolerant?

Taking care of your diet and maintaining a healthy lifestyle.

Lactose intolerance is not a serious condition, nor does it require too much concern.

It can slightly condition your lifestyle by preventing or limiting your intake of dairy foods (especially at social meals), but everything is adaptable, and you have lactase food supplements to help you cope with these occasional moments.

Which foods contain lactose?

FoodLactose content (g per 100g)
Cow’s milk4.7
Goat’s milk4.6
Human milk7.2
Cream2.0 – 3.2
Cheese (majority)Traces
Cottage Cheese1.4
Yoghurt3.2 – 4.8

Williams (2003).

Foods lactose

Foods containing lactose.

Which foods do I need to avoid if I’m intolerant?

Dairy products.

You may even consume dairy products, depending on the degree of hypolactation present, which, as we’ve seen, is normally up to 5g of lactose (the equivalent of 100ml of milk or approximately one yoghurt), which is tolerated by mild-moderate lactose intolerants.

All other foods that are not milk or milk products can be consumed without negative interference with the condition.

How do I know if I am lactose intolerant?

Symptoms of lactose intolerance

Most of the symptoms of lactose intolerance are limited to the digestive tract, and these include:

Stomach pains100%
Bowel distension100%
Bowel Sounds100%

However, there are also systemic symptoms associated with lactose consumption in intolerants, of unknown pathogenesis:

Loss of concentration82%
Muscle ache71%
Joint pain/stiffness71%
Mouth sores30%
Increased frequency of urination<20%

There are 4 main clinical tests for detecting lactose intolerance.

Yes, I’m going to answer your question:

No, suffering from these symptoms after consuming milk are not a reliable method of determining lactose intolerance. There are a a number of factors not related to lactose that can result in such symptoms.

Method 1 – Lactose Intolerance Test

Known for being an old method, not very specific and sensitive, with a high possibility of false positives and negatives.

It consisted of administering 50g of lactose, and after 30 minutes making a capillary puncture to measure the glycaemia (blood glucose concentration), which should result in a 20mg/100mL increase with respect to the concentration before the consumption of lactose.

Being so unreliable, despite its low price and wide availability, it is a completely obsolete test that is no longer used in clinical practice.

Method 2 – Hydrogen Breath Test

The gold-standard, that is, the test currently with the greatest reliability and validity.

There is a moderate chance of false positives and negatives.

As undigested lactose reaches the colon where it ferments, it generates gases, especially hydrogen; some of this methane is eliminated through breathing (the other part is the source of flatulence).

The amount of hydrogen exhaled after lactose consumption is measured several times, a curve is described, and if it increases significantly it is a sign of lactose intolerance.

Hydrogen curve

Lactose intolerance hydrogen curve, negative (left) and positive (right) .

It is a reliable, non-invasive and fairly accessible (cheap) diagnostic test. Thankfully.

Method 3 – Genetic Test

By itself it’s not very useful, but it is an excellent complement to determine the (primary/secondary) cause of hypolactation.

Secondary hypolactation can occur due to SIBO, Crohn’s disease, Rotavirus and other infections, consumption of certain antibiotics, etc. If this cause is corrected, the ability to digest lactose usually returns, it’s a “false intolerance”.

When hypolactation is primary (“real”), certain genes are highly specific for the diagnosis of intolerance. Lactose intolerance is “factory-programmed”, if you carry the C/C alleles (wild genotype) of the SNP C/T-13910 (rs4988235), you have been found to suffer from lactose intolerance.

Genetic test

Genotypic configuration of 2 SNPs of the TBI gene with persistence and non-persistence phenotype of lactase.

The mutant C/T and T/T genotypes are phenotypes with persistent lactase activity, and are lactose tolerant.


Most important SNPs coding lactase activity in the 2q.21-22 TBI region

Depending on the ethnic group, other more specific polymorphisms should be assessed, the one mentioned above being the one that codes activity in the Caucasian population.

It does have problems: it’s more expensive, and availability is lower; although genetic diagnosis is increasingly widespread we do not have widely distributed tools to determine genotype, especially of SNPs from other non-Caucasian ethnic groups.

Method 4 – Measurement of lactate activity in the intestinal brush

I won’t go into too much detail as it’s hardly used in the clinic and is more applicable to research.

It consists of doing an intestinal biopsy to extract a piece of enterocyte and directly evaluating the activity of the lactase it expresses.

It has many problems: it’s invasive, painful, expensive, and the expression of lactase is not uniform in the intestine, so it’s easy to over-/under-evaluate lactase activity.

What if I drink milk and I’m lactose intolerant?

Most lactose intolerant subjects can consume small amounts (around 5g = 100ml of milk) without significant adverse effects, as lactose intolerance is characterised by a deficit of the enzyme lactase (hypolactasia), not by a total absence of it (alactasia).

Lactose intolerancy

Stomach pain after drinking milk for someone who is lactose intolerant.

What is lactose-free milk?

Lactose-free milk, in Spain, is normally standard milk with Lactase added.

Free lactose milk

Although there are legitimate lactose-free milks, they are scarce and much more expensive.

This is because there are no regulations governing “lactose reduced” / “lactose free” claims, so companies regulate the thresholds for using these designations according to their own interests.

La AECOSAN (Spanish Agency for Food Safety and Nutrition) has established provisional thresholds for the determination of designations relating to the lactose content of foodstuffs:

  • “Lactose free” food products: are those that prove to be lactose free by following the most sensitive analyses available at the moment. In other words, less than 0.01% lactose.
  • “Low lactose” food products: are those with measurable residual lactose content and are generally below 1%

However, this is a proposal, prior to the drafting of a law that may establish a European Committee directive.

That’s to say, these recommendations are not binding or obligatory in any case.

Intolerance, indigestion, malabsorption

These 3 terms are related and are used indistinctly, incorrectly.

The whole development of this pseudo-pathogenic picture starts with the same condition:

Hypolactasia, any deficiency of the enzyme lactase.

This develops because of a non-persistence of lactase, a genetic condition considered a “wild-type” configuration, as most individuals show reduced lactase activity in the apical membrane of the jejunum after cessation of lactation.

In a minority of people, high lactate activity is maintained throughout adulthood (persistence to lactase phenotype, mutant genotype).

This deficiency condition of the enzyme that hydrolyses (breaks down) lactose leads to lactose indigestion, which is the inefficient digestion of the sugar due to deficiencies in lactase activity.

Lactose indigestion leads to lactose malabsorption, since lactose cannot be absorbed in its undigested form (Glucose+Galactose).

This leads to the development of lactose intolerance, which is the condition associated with gastrointestinal symptoms due to malabsorption of lactose by bacterial fermentation of sugar in the colon (at the end of the intestinal tract).

Intestinal metabolism lactose

em>Intestinal metabolism of lactose in a subject with intolerance.

What is the treatment for lactose intolerance?

There is no cure for lactose intolerance, the only 100% effective treatment is to avoid dairy products.

Other possible strategies thought to be useful are:

  • Using lactase as a food supplement alongside lactose intake.
  • Using probiotics from the genus Bificobacterium and Lactobacillus. Certain strains have lactase activity, and, if they colonise the intestine, could induce endogenous activity.


em>Lactase activity of different strains of bacteria.

This is why you’ll often hear that Yoghurt is lactose free.

In fact, it does have it, what happens is that thanks to the addition of lactic ferments for its development, it has its own lactic activity, derived from the microorganisms it contains, which contributes to the digestion of its lactose.


em>That’s why fermented dairy products are considered to be well-tolerated, because themselves intolerant to this sugar.

What function does lactase have?

Lactase serves to catalyse (assist) the process of hydrolysis of the glycosidic bond that binds glucose and galactose molecules.

As undigested lactose cannot be absorbed into the intestinal walls, deficiency (hypo-) or absence (a-) of lactase produces the classic symptoms of lactose intolerance.

Administering lactase exogenously (via medication or food supplements) is an excellent way to assist the (often) limited endogenous lactate activity.

Where is lactase?

Lactase is an enzyme located in the intestinal microvilli of the small intestine, especially in the jejunal region.

Small intestine

This is where most of the lactose is digested and absorbed, preventing it from reaching the colon, where it produces the symptoms.

Lactase is located in the lactase/floricin hydrolase complex at the intestinal brush border, located in the apical membrane (the one in contact with the intestinal lumen) of enterocytes (intestinal cells).

Produce it naturally

This isn’t possible.

Lactase activity is coded by your own genetic configuration – if you have mutant genotypes of the polymorphisms that determine how your lactate activity involutes from weaning, you can’t generate it by yourself.

You can supplement every lactose intake with lactase, which is the most common and widespread strategy, and very effective.

An emerging strategy is to use specific strains of probiotics that appear to be able to colonise the gut and express lactate activity, giving the (false) perception of increased self-activity.

When the microorganisms die, we return to the initial condition, but chronic consumption of bacterial ferments with these characteristics is very promising.

How to relieve symptoms of Lactose Intolerance

Don’t believe it?

Be careful, because 19 years later (after many studies showing the efficacy of lactase from this source) Portincasa et al., (2008) designed a very interesting study, using no less than 134 healthy subjects with lactose malabsorption.

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In addition to measuring the hydrogen they expelled, they used several tests to assess the symptoms they presented after consuming half a litre of whole milk without administering lactase; and after administering a reduced dose (6750 Lactase Units) and a standard dose (11250 Lactase Units) from Aspergillus Oryzae.

Graphic 2

Symptom relationship between groups that were not given lactase (placebo), that were given a reduced dose (Tilactase 6750); and that were given a standard dose (Tilactase 11250). On the left ‘bloating’ and on the right ‘abdominal pain’; above test ratings (in the dotted diagram), and below (area under the curve of the reports in the bar chart). (Portincasa et al., 2008)

The results were dramatic…

Obviously there was a quasi-perfect significance (confidence level) (P {;0.001) in the reduction of hydrogen production between the placebo group (which was not given lactase) and the experimental group (which was given lactase).

Furthermore, the results of the reduction of symptoms associated with lactose malabsorption speak for themselves: subjects showed highly significant reductions in symptoms of abdominal swelling and pain after administering even reduced doses of lactase extracted from Aspergillus Oryzae

How long does it take for the symptoms to disappear?

As soon as the consumption of dairy is stopped, the symptoms disappear, as the manifestations of discomfort are acute, if lactose is not consumed, there is no discomfort.

If lactase is used, it acts approximately 15 minutes after ingestion, taking effect up to 1 hour – 1 hour 30 minutes later, avoiding symptoms.

The time required to see a significant effect through consumption of bacterial ferments has not yet been clearly determined in humans, but it is expected to take around 3-4 weeks of use of effective doses of the particular strain that has lactose activity to colonise the gut.

Lactase for symptom relief

Its effects gradually diminish until it disappears if no longer used.

Lactase Supplementation

There are functional differences between the endogenous lactase that we synthesise in mammals and that which we obtain from yeasts, fungi and bacteria such as Saccharomyces lactis, Kluyveromyces fragilis, Aspergillus Niger or Aspergillus Oryzae.

The commercial enzyme complex preparations intended to hydrolyse lactose used in HSN brand products feature the patented Digezyme or Tolerase. Click here to find out more about the Digezyme Enzyme Complex.

Why Aspergillus Oryzae?

Because it’s a great source for obtaining lactase, demonstrating great effectiveness.

This is reflected in a wide variety of clinical trials and does not compromise the properties of milk as Saccharomyces Lactis or Aspergillus Niger do, which strongly alter the sweetness of the product and require maceration of at least 24 hours on average in order to hydrolyse the lactose (DiPalma & Collins, 1989).

These authors used 10 healthy subjects suffering from lactose malabsorption to see how much hydrogen they expelled (when tested).

In the trial they administered:

  • 50g of lactose without lactase;
  • 250mg and 500mg lactase from Aspergillus Oryzae.


The amount of hydrogen expelled by subjects in a test intended to be measured after a first test without lactase (B-1), a second test days later (B-2) and two tests administering 250mg lactase (L-250) and 500mg lactase (L-500) (Dipalma & Collins, 1989)

The conclusions were clear: the amount of hydrogen emitted by subjects with lactose malabsorption after administration of 250mg lactase from Aspergillus Oryzae was significantly lower.

And when they were administered 500mg, even less. What does this mean?

That the lactose was better digested, the absorption rate increased exponentially, decreasing the fermentation of the sugars of the milk in the large intestine and decreasing all the symptoms of discomfort it generated.

Get the Digestive Enzyme Complex now Digezyme 200mg from HSN.

How are lactase pills taken?

It depends on the source it’s obtained from.

In general, follow the instructions for use recommended on the product label:

Lactase nutritional info

Currently, practically all lactase food supplements marketed have an acute effect (lasting approximately 1h) and do not require prior maceration in the medium (milk or derivatives).

Because of this, Lactase 500mg from HSN should be used 15 minutes before the meal containing lactose, and should be used again if another meal is made even a few hours later on the same day.

Protein for lactose digestion

You’ll find all the benefits of this enzyme in products of dairy origin, such as


Lactose is the sugar in milk and its derivatives.

Milk, like any other food, is not compulsory (except in breastfeeding, where there are also substitutes), although it is a complete food of high nutritional interest.

Losing the properties of dairy products because of mysticism or “because we are the only species of mammal that continues to drink milk after lactation” is a reflection of real ignorance.

If we are like this, it’s because we have evolved and adapted to environmental exposure, including post-lactation dairy consumption.

If you are lactose intolerant, you can supplement your intake with lactase, although it’s best to leave it for specific times and to generally avoid dairy products in amounts that cause you discomfort.


Tolerance, intolerance and mixed expression in intolerant subjects and in singular or divided doses.

Bibliographic references

  1. Corgneau, M., Scher, J., Ritie-Pertusa, L., Le, D. t. l., Petit, J., Nikolova, Y., … Gaiani, C. (2017). Recent advances on lactose intolerance: Tolerance thresholds and currently available answers. Critical Reviews in Food Science and Nutrition, 57(15), 3344–3356.
  2. Fassio, F., Facioni, M. S., & Guagnini, F. (2018). Lactose maldigestion, malabsorption, and intolerance: a comprehensive review with a focus on current management and future perspectives. Nutrients, 10(11).
  3. Flynn, A. (2016). Nutrition and Health: Galactosemia. In Reference Module in Food Science.
  4. Ghoshal, U. C. (2016). Overview of hydrogen breath tests in gastroenterology practice. In Evaluation of Gastrointestinal Motility and its Disorders (pp. 87–94).
  5. Szilagyi, A., & Ishayek, N. (2018). Lactose intolerance, dairy avoidance, and treatment options. Nutrients, 10(12).
  6. Ugidos-Rodríguez, S., Matallana-González, M. C., & Sánchez-Mata, M. C. (2018). Lactose malabsorption and intolerance: a review. Food and Function, 9(8), 4056–4068.
  7. Williams, C. A. (2003). Encyclopedia of food sciences and nutrition. In B. Caballero (Ed.), Encyclopedia of Food Sciences and Nutrition (Second Edition, pp. 2843–2846).

Related Entries

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About Alfredo Valdés
Alfredo Valdés
A specialist in Pathophysiology and biomolecular effects on nutrition and sportive activity who will show you the elaborate world of sports nutrition in his articles, employing a simple and critical writing.
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