Lactose intolerance: everything you need to know

Within the food intolerances or food intolerances themselves, one of the most common is the lactose intolerance, which stands out alongside the gluten intolerance. In fact, it is believed, it is estimated that approximately 70% of the world population presents in its diet some type of intolerance or lactose problem; and of that percentage many of them do not know it.

It is as we see a type of intolerance more common than you think, which occurs as a result of the existence in our body of a deficit of lactase, an enzyme produced naturally by our small intestine, which is able to unfold the lactose in glucose and galactose, so that they can be better absorbed by the body. But nevertheless, If lactase levels are low, it is known as lactose intolerance..

What is lactose? ...

The lactose (milk sugar), it decomposes itself into two other simpler sugars (glucose and galactose), an issue that occurs thanks to the action of the enzyme lactase. This process takes place specifically in the small intestine, an organ where it is possible for glucose to be absorbed into the bloodstream.

It is estimated that about 5% of the milk is lactose, a disaccharide formed by a particle of glucose and a particle of galactose. It becomes, therefore, the main carbohydrate of milk.

... And the lactose intolerance?

Within the process of absorption of lactose in the small intestine, when there is a lactase deficit the lactose passes into the large intestine without decomposing and begins to ferment. That is, the organism of the affected person has a low amount of lactase, which, as we indicated earlier, is the enzyme that makes milk sugar digestible.

This results in gases Y acidity, which obviously generate a series of stomach problems and discomfort that are felt every time you eat a food that contains lactose.

That is, we can define lactose intolerance as the inability to digest normal amounts of milk sugarNo hassles or problems.

It is estimated that around 15% of the population does not have enough lactase in their organism, so when they consume a food with lactose they have a lot of difficulties to digest it normally.

Symptoms caused by lactose intolerance

To a certain extent it can be difficult to know if we are lactose intolerant or not, given that although there may be adverse reactions or occur, many people are unaware that they have this condition.

And this is because the symptoms of lactose intolerance are not the same in all people, since some people get constipation, stomach discomfort, diarrhea ... and other rhinitis, heavy digestion, or skin problems.

However, a more or less clear warning sign appears when drinking a glass of milk soon after a series of digestive symptoms, such as flatulence, colic and swelling. In fact, the ingestion of a large amount of lactose is required for the most obvious symptom to appear: diarrhea.

Tests to diagnose this intolerance

Although the symptoms may help, it is best to perform Lactose tolerance tests, especially if you suspect that you may be suffering from this intolerance.

These tests measure the ability of the intestines to break down both lactose and other dairy products. There are basically two:

  • Blood test for lactose intolerance:It pursues the objective of looking for the presence of glucose in the blood, since when glucose is broken down our organism produces it. It is considered normal if within 2 hours after ingesting a lactose solution glucose rises more than 30 mg / dL, and abnormal if the glucose level rises less than 20 mg / dL.
  • Hydrogen breath test:It is the method of choice by most specialists. It consists of measuring the amount of hydrogen in the air that the person exhales. Its implementation is simple, since the patient is asked to breathe inside a balloon-type container, and then drink a liquid flavored with lactose. These samples are taken at determined periods, verifying the level of hydrogen. Normally, when there is no lactose intolerance, there is very little hydrogen in the breath. However, it increases when the body has problems breaking it down and absorbing it. It is considered normal when the hydrogen increase is less than 12 parts per million.

Diet in a person with lactose intolerance

Foods rich in lactose

It is evident that, when a person suffers from lactose intolerance, they must decrease the consumption of milk and other dairy products. But from a nutritional point of view it is not much less advisable to completely eliminate the consumption of both milk and dairy products, given that they are foods that contain a higher concentration of calcium, essential to maintain a correct state of health of the bones.

So, the key is to consume tolerated dairy, since the consumption of this type of food will produce an adaptation of our organism, increasing with the passage of time the tolerance to them.

However, below we summarize which are the dairy products with the highest presence of lactose: cow's milk, milk powder, milkshakes, dairy products, cream, fresh and fermented cheeses, mascarpone cheese, Quark cheese, feta cheese, cream milk, dairy desserts, butter, margarine, ice cream and béchamel sauce.

DairyLactose content (grams per 100 grams)
Cow milk5
Goat milk4,5
Sheep milk5,1
Skimmed milk powder5,3
Condensed milk12,3
Fresh cheeses2,4-2,7
Cured cheeses< 1

Foods that can have lactose and you probably do not know

In addition to the dairy products themselves, did you know that there are also some foods and food products that, in their composition, can contain lactose? The most common are the following:

  • Purees and soups: most carry lactose. They emphasize the mashed potatoes and other creams or purées.
  • Bread: usually carry milk or lactic ferments. It is important to look at the labeling or ask at the bakery where you usually buy the bread.
  • Cold cuts and sausages.
  • Cakes and fried meat.
  • Desserts: sorbets, cakes, yoghurts, milkshakes, punches, malts, milk chocolate.
  • Battered.
  • Fortified cereals.
  • Spirits

We must also pay attention to other products that are not foods but can contain lactose, such as:

  • Medicines
  • Vitamin complexes
  • Dentifrices

Safe food without lactose

Here's what foods you can eat calmly if you're lactose intolerant. However, you can learn more information in our special article on lactose-free foods:

  • Natural fruit
  • Nuts
  • Cereals (not enriched)
  • Eggs
  • Honey
  • Jams and preserves
  • Potatoes
  • Rice
  • Pasta
  • meats
  • Vegetables
  • Fish
  • Vegetables
  • Tofu
  • Plant milks: soya milk, coconut milk, rice milk, almond milk, canary seed milk, nut milk or oat milk.

As we can see, the key is to look at the nutritional labeling of the different foods and food products that you buy in the supermarket, and always inform yourself about which ones you should avoid.

And what about milk without lactose? Can they be taken safely?

Unlike what popularly and erroneously thinks, milk without lactose is no more or less healthy than normal milk. It's just an equally natural drink that contains lower levels of lactose.

The only difference is that, at the time of producing it, the producers add small amounts of lactase in the milk, so that what is achieved is that the lactose is broken down into glucose and galactose, the two molecules that we previously saw form it.

So, Both lactose-free milk and low-lactose milk are suitable for people with lactose intolerance, but it is not advisable to consume them if we are not intolerant, since small temporary lactose intolerances can occur.

On the other hand, low-lactose foods, like milk without lactose, They are not suitable for allergic to milk, since this type of food continues to maintain the original proteins of animal milk.


  • Vandenplas Y, Marchand J, Meyns L. Symptoms, Diagnosis, and Treatment of Cow's Milk Allergy. Curr Pediatr Rev. 2015; 11 (4): 293-7. Available at: //
  • This article is published for informational purposes only. You can not and should not replace the consultation with a Nutritionist. We advise you to consult your trusted Nutritionist. ThemesFood intolerances

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