Lactose intolerance test: 7 ways and methods

Sabina Muminović Last updated: 20 October 2023

Many people experience discomfort after eating or drinking dairy products. Many suspect they are lactose intolerant but aren’t completely sure. And if you aren’t sure it’s hard to act. This article is here to help! We wrote it to clarify some things about lactose intolerance. It starts off with a bit of theory that’ll help you understand what exactly lactose intolerance is and who’s predisposed to it.

However, if you’re only interested in ways of checking if you are lactose intolerant, you can skip the first part of the article and jump straight to testing methods via the table of contents.

In this article

What exactly is lactose intolerance?

Does lactose intolerance just happen? Are you predisposed to it?

What are the symptoms of lactose intolerance?

Simple check #1: Replace milk with lactose-free milk

Simple check #2: Limit yourself to low lactose cheeses

Simple check #3: Take a lactase enzyme pill with all dairy products for a few weeks

DNA test: Are your genes hindering your lactase production?

Clinical method #1: Hydrogen breath test

Clinical method #2: Lactose tolerance test

Clinical method #3: Stool acidity test

How to treat lactose intolerance?

What exactly is lactose intolerance?

What exactly is lactose intolerance?

Lactose intolerance means that your body cannot easily digest lactose, which is a type of sugar found in milk and some dairy products.

Like most sugars, lactose is broken down by enzymes during digestion. This happens in your intestinal tract so that your body can absorb it as an energy source. The enzyme responsible for breaking down lactose is called lactase.

Lactose intolerance occurs when your small intestine doesn’t make enough lactase enzyme to break down all ingested lactose. That means that too much lactose enters the large intestine and ferments there.

Fermentation is the reason why lactose intolerance causes uncomfortable symptoms such as gas, belly pain, diarrhoea and bloating.

There are different levels of being lactose intolerant. Some people can’t digest any milk products at all, others can consume a small amount without any problems. The variability happens because lactose intolerance is not an “all or nothing” deal, it simply means that you have lower lactase enzyme levels than normal.

It’s also important to note that lactose intolerance is not the same as milk or food allergy. Don’t confuse the two. If you have dairy allergy, your body reacts to the proteins in dairy products as if they’re dangerous invaders. It releases substances that cause allergy symptoms. This allergic reaction can be mild (rashes) to severe (trouble breathing, loss of consciousness).

Does lactose intolerance just happen? Are you predisposed to it?

You can be genetically predisposed to lactose intolerance (as you’ll see when we talk about a DNA test) or it can appear due to certain circumstances.

As you’d expect, most babies and small kids have the lactase enzyme so that they can digest their mothers’ milk. But as time passes, lactase can begin to disappear in some people.

Lactase intolerance commonly runs in the family, but it also depends a lot on your ethnic group. Some ethnic groups are more likely to develop lactose intolerance.

According to studies

  • 60 to 80 % of Asians (up to 95 % in some parts of Asia),
  • 60 to 80 % of Africans and African Americans (up to 95 % in some parts of Africa)
  • and 50 to 80 % of Hispanics are lactose intolerant.

On the other hand, only 2 to 10 % of Northern Europeans have lactose intolerance, which can be connected to centuries of their dairy-rich diet.

Lactose intolerance can develop at any age. It may be triggered by another medical condition, such as Crohn’s disease, a short-term illness such as the stomach flu or as part of a lifelong disease such as cystic fibrosis. Sometimes it happens after a surgery that removes a part of the small intestine. Such cases of lactose intolerance can be temporary or permanent. Sometimes it might even develop without a specific trigger.

In rare cases, even newborns can be lactose intolerant. Premature babies can be lactose intolerant to their intestines’ inability to make lactase at that point and the condition can go away later. However, if the infant remains lactose intolerant, it typically means it won’t be able to eat or drink anything containing lactose during its life.

What are the symptoms of lactose intolerance?

As we’ve already mentioned, lactose intolerance isn’t an all or nothing deal. That’s why its symptoms vary in their form and severity.

Symptoms may include:

  • bloating of your intestine and stomach area,
  • abdominal pain or cramps in that area,
  • rumbling sounds in your belly,
  • gas,
  • diarrhoea,
  • vomiting.

Symptoms usually begin 30 minutes to 2 hours after ingesting anything that contains lactose. Many people suspect they might be lactose intolerant, but aren’t completely sure.

There are a few ways you can check if you are indeed lactose intolerant. We’ll start with three simple methods you can do at home and then move onto more scientific and clinical tests.

Simple check #1: Replace milk with lactose-free milk

This is the simplest way to check if you’re lactose intolerant. If you drink milk on a daily basis, replace it with a lactose-free alternative. See how you feel after a couple of weeks. You can do this even if you don’t suffer from severe symptoms.

If your well-being improves significantly, you’ve got your answer. You are lactose intolerant, but just cutting regular cow’s milk from your diet can already help you a lot.

Simple check #2: Limit yourself to low lactose cheeses

If you’re a cheese lover, you might want to give this method a try. There are quite some cheeses that only contain traces of lactose, so you can still get your cheese-fix during your “lactose fasting”.

Here’s a list of 9 low lactose cheeses for you:

  • Muenster (0-1.1% lactose range)
  • Camembert (0-1.8% lactose range)
  • Brie (0-2% lactose range)
  • Cheddar – mild and sharp varieties (0-2.1% lactose range)
  • Provolone (0-2.1% lactose range)
  • Gouda (0-2.2% lactose range)
  • Blue (0-2.5% lactose range)
  • Parmesan (0-3.2% lactose range)
  • Swiss (0-3.4% lactose range)

On the other hand, the fresher, creamier cheeses tend to have a higher lactose content as they have a higher sugar content than aged, hard cheeses. You should avoid cottage cheese and ricotta if you have a sensitive stomach.

Stick with the mentioned 9 cheeses or add other aged, hard varieties and see how you feel. If you’re feeling better, it probably means you’re lactose intolerant.

Simple check #3: Take a lactase enzyme pill with all dairy products for a few weeks

If you’re feeling uncomfortable after consuming dairy products, consider taking a lactase enzyme pill with them and see how you feel. You can get these pills in pharmacies and even grocery stores and you don’t need a prescription for them.

All this pill does is help to break down lactose in your stomach and it can be a real game-changer.

Try taking the pills for a couple of weeks and see if you feel better (or simply normal) after you consume dairy products. If you do, you now have your remedy when you absolutely need to have a piece of a tasty cheesecake or a scoop of ice cream.

DNA test: Are your genes hindering your lactase production?

First, you need to know that a DNA test is not a clinical test that would conclusively prove that you are lactose intolerant.

However, some people are more genetically inclined to be lactose intolerant than others.

Lactase production depends on your LCT gene, which is located on Chromosome 2. The LCT gene contains instructions for making the lactase enzyme. People with a normally functioning LCT gene produce lactase and can process dairy foods without unpleasant symptoms.

However, some genetic variants can cause the LCT gene to mildly, moderately or severely reduce lactase production, leading to lactase deficiency in your intestines. The reason for the absence of the lactase enzyme is often the MCM6 gene, which is actually not functionally related to lactose metabolism, but it regulates the activity of the LCT gene.

If you have unfavourable copies of the MCM6 gene, consuming dairy products can lead to lactose intolerance symptoms.

Okay, so if a DNA test can fairly accurately predict how much lactase enzyme you produce, why doesn’t it prove if you are (or aren’t) lactose intolerant?

Because we know primary and secondary lactose intolerance. 

Primary lactose intolerance is the most common cause of lactose intolerance worldwide and affects up to 75% of people. Most people with primary lactose intolerance are genetically predisposed to significantly reduced lactase production, which further decreases with ageing.

The genetic result can indicate primary lactose intolerance.

However, as you know by now, intolerance can develop due to different reasons, such as the injury to the small intestine, resulting from infection, celiac disease, inflammatory bowel disease, or other diseases. That’s secondary lactose intolerance.

There are also other causes for lactose intolerance. We know developmental lactose intolerance, which may occur in premature babies and usually improves over a short period. Another type is congenital lactose intolerance, an extremely rare genetic disorder in which little or no lactase is produced from birth.

​Several studies have shown that the genetic test has an excellent agreement with the hydrogen breath test (more about it soon), commonly used in laboratories for lactose intolerance testing. The overall concordance between a genetic test and the hydrogen test was reported to be above 90%.

While a genetic test cannot conclusively tell you if you’re lactose intolerant, it does fairly accurately predict how much lactase enzyme you produce which is correlated with the primary lactose intolerance.

But the biggest advantage of a DNA test is that it usually doesn’t analyze just lactase production, but also other genes that affect your metabolism. Take a look at all that you can learn from a MyLifestyle DNA test here.

Clinical method #1: Hydrogen breath test

This is the most common of the three clinical tests where you have to visit a doctor. Here’s the procedure:

  1. After fasting, you breathe into a balloon-like device that measures the amount of hydrogen in your breath. This is to establish your base levels of hydrogen.
  2. You drink a solution containing lactose (usually simply water and lactose).
  3. You breathe into the balloon-like device at regular intervals (usually every 15 minutes) for 2 to 3 hours. Your doctor measures how much hydrogen you exhale.
  4. If the test result shows a rise in hydrogen of more than 12 parts per million over your original fasting test it indicates lactose intolerance.

As we usually exhale very little hydrogen. Increased levels of the amount of hydrogen in your breath are a clear sign that your body is not properly breaking down and digesting lactose.

Clinical method #2: Lactose tolerance test

This test requires your doctor to take a fasting blood sample to see how much glucose is normally in your blood.

Then you’ll drink a liquid containing high levels of lactose. After two hours your doctor will do another blood test and to see what’s your blood glucose level after consuming lactose.

When your body digests the lactose normally, it breaks it down into a simpler sugar – glucose. Thus your glucose levels should rise.

If your glucose levels don’t rise or rise less than 1,11 mmol/L within two hours of drinking the lactose liquid, your body is not properly digesting lactose and you are lactose intolerant.

Clinical method #3: Stool acidity test

This is the least common test of the three clinical methods and is usually performed on infants or small children as they are not eligible for other tests.

Once again the infant or child will have to drink a liquid containing lactose. After waiting for a while the physician will take a stool sample.

Normally, the stool is not acidic. However, if the body is unable to break down lactose, it will ferment in the intestines and create lactic acid, which can be detected in the stool. This means the child is lactose intolerant.

How to treat lactose intolerance?

Although there is no cure for lactose intolerance yet, you can certainly control the symptoms by adjusting your diet.

It is very likely that you do tolerate a certain amount of lactose. Most lactose-intolerant people can consume 8-10 g of lactose daily without trouble, some even 50 g, but highly sensitive people have to limit it to 1 g daily at most. Observe your reaction to consumed lactose for a while, and determine how much lactose you tolerate.

To lower the amount of lactose in your diet you should limit the amount of milk and other dairy products or replace them with their lactose-free alternatives. If you can tolerate some lactose and want to eat a small amount of milk products, it’s best to do it in small servings with your regular meals.

If you are highly sensitive to lactose, pay attention to food labels on processed meat, margarine, bread, cereal, instant soups and gravies, cake mixes, and biscuits, because lactose can also be present in non-dairy foods.

You can also add a lactase enzyme pill to the dairy products you consume to help your body break down the lactose.

Studies have shown that some probiotic yoghurts can alleviate symptoms of lactose intolerance by modifying the metabolic activity of microbiota in the colon.

In addition to reduced lactose content, their bacterial content also favourably influences the balance in the intestinal flora which can lead to the alleviation of lactose intolerance. These bacteria may even produce their own lactase enzyme, and consuming lactose from dairy products can promote the growth of these bacteria in the colon.

Over time, these effects can lead to greater lactase content in the gut, improved lactose digestion, and eventually the elimination of intolerance symptoms.

One of the main concerns for lactose-intolerant people is ensuring you get enough calcium as milk products are often the main source of it. Calcium is especially important for children, teens, pregnant women, and women after menopause. Fortunately, there are many non-dairy foods that contain calcium, such as:

  • broccoli, okra, kale, collards, and turnip greens,
  • fish canned with bones (e.g. sardines and salmon),
  • calcium-fortified products,
  • almonds.

That’s it. Now you know exactly what lactose intolerance is, why it happens, how you can check if you’re lactose intolerant and what to do about it. Hopefully, you’ll find out you’re not actually lactose intolerant in which case we urge you to celebrate with a big cheese plate.

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