Signs You May Be Lactose Intolerant and Don’t Even Know It

· March 15, 2017
Did you know that you might be lactose intolerant and not even know it? Lactose intolerance doesn't have to be serious, but it can affect your life. Learn about the symptoms and diagnosis.

Although some may say food allergies are an invention of the new century, they’ve actually existed ever since human beings started drinking milk and eating grains and legumes.

Today, we’ll tell you about the signs of lactose intolerance so you can determine whether or not you have problems digesting this food.

What is lactose intolerance?


Humankind’s gradual genetic mutations have allowed us to keep drinking milk into adulthood.

However, some people don’t produce enough of the enzyme to absorb the lactose. That’s when lactose intolerance happens.

Lactose intolerance is a disorder that comes from a deficiency in the enzyme in charge of digesting lactose. When it is poorly absorbed by your body, the milk sugar passes to the colon where it ferments and causes gas.

The consumption of milk, yogurt or ice cream by a lactose intolerant person doesn’t cause serious or irreversible damage in the intestinal tract, but rather temporary symptoms.

Many people think they have this problem when actually they have excessive bacteria growth, celiac disease, or intestinal inflammation.


It’s worth noting that the majority of people with the intolerance have primary lactose intolerance; in other words, they can drink a glass of milk (or equivalent milk products) without any symptoms and even have dairy with their meals without any intestinal issues.

They also have the option of consuming products that are low in lactose or taking lactase supplements.

Symptoms of lactose intolerance

Lactose intolerance shows signs between 30 minutes and 2 hours after eating or drinking foods containing lactose.

The severity of the symptoms depends on the person, the amount consumed, and how much (or little) of the lactase enzyme is in the stomach.

To clarify, these signs don’t always mean lactose intolerance. They can be “shared” with other conditions or gastrointestinal disorders (especially the stomach flu).

A “hint” that can help is looking at the time that symptoms appear. If it’s after eating or drinking milk, yogurt, cheese, ice cream, etc., it’s more likely to be due to lactose intolerance.

Here’s why:

  • The fermentation of the lactose by the intestinal bacteria produces more acidic stool which can cause irritation or burning when going to the bathroom.
  • This process can also trigger bloating or abdominal pain and more gas (that lasts for several hours after eating dairy).
  • It’s likely that the stool and flatulence will be foul-smelling and strong.

Diarrhea or constipation can go hand in hand with lactose intolerance, since it produces an imbalance in intestinal flora. Stomach cramps are common, too.

Lactose intolerance in kids and teens often means nausea or vomiting.

For chronic cases (secondary lactose deficiency) you may also see:

  • Noticeable weight loss
  • Perianal redness
  • Abdominal spasms
  • Explosive diarrhea

In addition, people with these cases experience skin problems, extreme fatigue, and pain in their extremities.

How do I detect lactose intolerance?

If you think you have this problem, it’s important to see a specialist. A professional will be able to diagnose your symptoms.

The most common tests are:

Glycemic response testing

  • First, blood is drawn to measure initial glycaemia levels.
  • Then, an overload of lactose is given, 50 grams every 30 minutes for 2 hours (4 doses).
  • After that, blood is drawn again to measure glucose.

If the measurements are the same, then lactase is not acting as it should.

However, this test is not very specific, since there are other disorders that can alter glycaemia, like diabetes mellitus.

Hydrogen breath test

This method is used the most for detecting lactose intolerance. The person consumes a lactose solution at 15-minute intervals, then blows into an airtight bag.

When milk sugars aren’t digested and move to the intestine, bacteria uses them as food and produce hydrogen.

Therefore, if your breath has a good amount of hydrogen, it is probably due to a problem digesting lactose.

Small intestine biopsy

An esophageal or gastrointestinal endoscope is used to perform this test.

The tissue fragments obtained are then analyzed in the laboratory to determine the presence or absence of lactase in the mucus.

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Stool acidity test

This test is mostly for small children where their young age makes other studies too risky or impractical.

Genetic test

This test’s objective is to detect primary lactose intolerance caused by the MCM6 gene.

A blood or saliva sample is all it takes to analyze the two polymorphisms associated with this condition.