What Is “Lactose Intolerant”?


Dear Reader you may have been having problems with your tummy ± your general health. And at a health centre, you may have been told that you are lactose intolerant. This article will help you with the question that is probably bothering you – “what is lactose intolerant?”

You are wondering about your everyday life activities and your surroundings. Among them, what cause lactose intolerance?

You need to know what the next steps are. Is there lactose intolerance testing to confirm the diagnosis or suspicion of lactose intolerance?

This article is going to deal with those pressing issues. It will teach you how to recognise and how to deal with lactose intolerance.

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Lactose is a sugar or carbohydrate that is found naturally in milk. Fresh milk contains lactose which is in smaller percentages than milk products. Of the milk products, fat-free ones contain higher quantities of lactose.

The sugar lactose is metabolised or broken down by an enzyme called LACTASE. It is deficiency of this enzyme, that renders people unable to handle lactose taken in with food. These subjects cannot digest the lactose, which passes through the gut.

Undigested lactose reaching the intestines causes a variety of symptoms. This is what lactose intolerance is.

Lactose is broken down by certain healthy bacteria that grow in milk and milk products. The bacteria fall in the group of bacteria called lactobacilli. (“Lacto” means milk; “bacilli” are rod-like bacteria when seen under the microscope.)

The above fact about healthy bacteria and milk, will be revisited when we deal with lactose intolerance treatment below.


People can be born with a deficiency of the enzyme lactase. That congenital deficiency can be inherited. This subset of people, manifest lactose intolerance from an early age, to varying degrees.

The genetics of lactose intolerance are such that, people of African descent are among the worst affected. Up to 80% of people of African origin have a degree of lactase deficiency resulting in lactose intolerance.

But some people develop lactose intolerance later in life. The onset of this secondary lactose intolerance can be gradual, or it can be sudden. It depends on the cause of the loss of digestive ability.

Acquired causes of lactose intolerance include:

  • malnutrition, especially undernutrition. The lining of the gut, just like other tissues in the body, requires good, balanced nutrition for vitality. Unfortunately good nutrition is not possible for too many people in the world.
  • the (prolonged) use of antibiotics (especially broad spectrum antibiotics). These do not only kill unwanted bacteria (germs), but also the good, desirable bacteria such as those of the gut.
  • certain habits like laxative abuse. This erodes away the lining of the gut, together with its functionality. Over a course of time, some of the damage is irreversible.


Lactose reaching the large intestines undigested can cause:

  • flatulence or a lot of gas
  • abdominal fullness or bloating
  • borborygmi or rumbling noises in the intestines
  • abdominal cramps
  • abdominal pain
  • indigestion
  • nausea and belching
  • diarrhoea
  • fatty stools


Generalised symptoms also do occur. They include feeling weak or malaise.

All the above symptoms, typically occur shortly (2 – 3 hours) after taking in food or drink containing a lot of lactose. These foods include (fresh) milk, other dairy products, beans and peas.

When the amount of lactose in the gut has declined significantly (1/4- to 1/2-day), the symptoms typically also decline until they disappear.

The above pattern is what makes the clinical diagnosis of lactose intolerance relatively easy. Members of the public usually suspect the problem, even before they go to a healthcare professional.


Lactose intolerance can be suspected on clinical grounds, as explained above. But there exists ways of confirming the diagnosis. There are indeed, Lactose Intolerance Tests. Your healthcare provider can arrange with a lab to do the test(s) for you, which will require you to set aside a few hours.

The Lactose Intolerance Tests are in two forms. But both involve being challenged with a concentrated solution of lactose:

  1. the Hydrogen Breath Test. In this test, people with lactose intolerance, produce too much hydrogen in their breath over a period of hours after lactose ingestion. This hydrogen is measurable.
  2. Blood Test for Glucose. People with lactose intolerance, fail to convert the ingested lactose to significant amounts of blood glucose. Thus, after being challenged with the lactose bolus, their blood glucose rises insignificantly or not at all.

Sometimes people get tested for lactose intolerance with unspecific abdominal or generalised symptoms. And sometimes, lo and behold, lactose intolerance is detected!


Sometimes, members of the lay public, after picking up an intolerance of foods such as dairy and legumes, avoid such foods at all costs. They may not even suspect that it is lactose intolerance that they are having; they may have never heard of the term!

What is important is that a healthcare professional be involved, to supervise the treatment. Indeed, the generalist health practitioner may need to enlist the help of specialised professionals like Dietitians and Gastroenterologists in some cases.

The cornerstone of treatment of lactose intolerance, is AVOIDANCE OF LACTOSE.

But the degree of such avoidance depends on the severity of the lactose intolerance. Some people can still be able to gobble up a little beans or cheese or whatever, to avoid starving. But for some sufferers, total avoidance of lactose containing foods is necessary and unavoidable.

There now exist, at least in some parts of the world, brands of lactose free milk and other dairy products (please see Product Links above). The lactose gets removed by manufacturing processes. And, fortunately, the cost of lactose free milk is not impossibly high.

Fermented dairy products (yoghurt, cheese, sour milk, etc) are also advantageous. Lactobacilli as described earlier, when fermenting the milk, digest the lactose content thereof. This is what gives such foods their sour taste.

People with lactose intolerance can therefore still be able to enjoy dairy products. Sour milk, yoghurt, etc, can be used in place of fresh milk in for example, cereal dishes. This is important especially for children and adolescents, who need calcium for their growing bones.

To prevent Secondary Lactose Intolerance, actions that disturb the gut should be avoided. Prolonged use or abuse of systemic antibiotics should be avoided as much as practicable.

Where the healthy gut flora has been disturbed or destroyed by e.g. antibiotics, there are measures that can be undertaken to restore the bacterial population:

  • regular consumption of yoghurt. But it has to be yoghurt of good enough quality (Dietitian advice may be needed)
  • probiotic preparations (such as linked above in Paragraph 2). These include capsules, gummies (not preferred because of sugar content), special yoghurt brands
  • (it is not clear whether sour milk as is used throughout e.g. Africa, can replenish healthy gut flora sufficiently)


Lactose intolerance is a common condition throughout the world. In some parts of the world, it is extremely common. The severity differs.

In some instances, lactose intolerance is just a bit of an inconvenience. In some cases, it is a severe disease, causing a lot of discomfort or ill health.

Recognition of lactose intolerance is not difficult, especially to a trained health professional. But laboratory confirmation is also possible.

And lastly, HELP is available for sufferers. Do dear Reader, kindly seek professional help where required or possible. And do use products such as linked above, to improve the quality of your health.


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8 Replies to “What Is “Lactose Intolerant”?”

  1. What a pleasant site to visit with lots of great information laid here. It is very explanatory. If there are things I so much appreciate about this article is the fact that it gives a detailed information about the general health issues, most importantly our tummy upset and the awareness of lactose intolerant disease. Thanks for sharing, i have gained some genuine knowledge from perusing your article.

  2. Thank you so much, this post gave me so much clarity. I have known and heard the term Lactose Intolerant a lot of times but never understood in-depth, what is it? what causes it? And how best to deal with it . I can confidently say I feel empowered.

    I am curious though why is it that it affect people of African descent more?

    1. Hi Bogadi,

      Thanks ever so much!

      I am glad that you found clarity and empowerment. The theory is that African people’s lactase enzyme lost its activity over centuries due to the widespread use sour milk. Sour milk contains little or no lactose. So, as the saying goes, “use it or lose it!” Africans lost their lactase activity because they were using milk that did not need the enzyme to digest. And the deficiency is passed on through genetics, wherever in the world Africans go!

      Regards. 😊

  3. Thank you for this article, I have actually heard people say that they are lactose intolerant but I never really bothered to know what it meant, reading this article has now made me understand what it all means. My question is, what would make the lactase not function in the way it is supposed to function? What should we avoid in order not to be in this situation?

    1. Hi Maureen,

      Enzyme activity malfunction or complete absence actually affects many of the scores of enzymes we have in our bodies. And in many cases, the problem is inherited or genetic. People who have inherited a defective gene, cannot produce enough signal for the manufacture of the protein that is the enzyme. Or they could signal production of a defective / abnormal protein. An enzyme that is lacking in quantity or defective in molecular structure, does not function properly.

      But also, environmental factors sometimes play a role in interfering with the functioning of the enzyme.

      Thanks and regards.

  4. The first thing that comes to my mind is a question. So, can someone be cured of lactose intolerance? I mean take treatment and afterward, take dairy products without any inconvenience.

    And today we are discovering other plants based milk, do they have lactose also in them? If yes, can a lactose intolerant person be troubled in the same way?

    Thanks for sharing!

    1. Hallo,

      Treatments for lactose intolerance do exist. The intake of healthy gut bacteria as contained in probiotic preparations and yoghurt, does eventually cure SOME people. But a Specialist Gastroenterologist should be consulted if treatment is not successful.

      The idea of milk alternatives is exactly that – to protect people from LACTOSE! So, many such milk alternatives are well tolerated. I need to clarify this – even soy milk does not contain lactose! I am mentioning this specifically because beans trouble lactose intolerance sufferers, and they may be weary of milk made from soy beans!!

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