Response To "Am I Lactose Intolerant?" Article at Fitness Reloaded

Posted on 11 Jul 2015 00:16

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By Eric Troy

I have a couple of problems with a new article called Am I Lactose Intolerant that appeared on the website Fitness Reloaded. This article, written by Ann Zakrisson, seems to be claiming that lactose intolerance is a trend or fad and that those who self-identify as lactose intolerance are simply a part of this trend, with little basis for such a belief.

If you need more information on lactose intolerance and what it is, see the lactose intolerance overview here at GUS. A great deal of what is in this overview will be discussed here, often in more detail.

Is Lactose Intolerance Similar to Gluten Intolerance?

At a time when fads such as gluten-free or wheat-free (wheat belly, wheat brain) are still rampant, my first reaction is that this article is comparing lactose intolerance to these other trends. Although the article does not specifically mention gluten-free diets and other such trends, this, to me, is too big of an elephant in the room to ignore, and I am assuming that many readers will assume that this comparison is being made. As well, the newsletter form from the site admin, presented at the top of the page, mentions gluten and GMO's, which would certainly cause the average reader to make the connection (peripheral cues are important and should not be ignored).

Now, there are undoubtedly certain groups, leaning heavily on dietary restriction, that have taken up the "dairy elimination" banner along with gluten, GMO's, and any other of the modern food boogeymen. According to professional dietitian Gabrielle Maston, it seems to be a growing trend among naturopaths, and again, is part of a constellation of foods they advise people to eliminate from their diets. Dietitians never diagnose and are not trained to do so.1

Also, sundry "nutritionists" are always diagnosing folks with this or that food intolerance and I've no doubt that among groups of "wellness gurus" and unqualified nutritionists, this is a growing practice. However, neither of these groups is a specific professional group. A nutritionist can be almost anybody, especially on the web, and wellness practitioner, well, there is no point in even trying to pin this down. We can find trends among groups, sure, but to say that dairy elimination is a fad is quite a different thing than to say that lactose intolerance is a fad.

So, I have three problems to discuss about the piece. The first, is that I do not agree with comparing lactose intolerance with a "trend" such as the many dietary-restriction trends that are popping up, gluten-free being the perhaps the best known. Dairy restriction may be a trend, and there are many stated reasons for restricting dairy besides lactose, but this is not the same as lactose intolerance itself being a trend.

To be clear, non Celiac gluten intolerance is an imaginary problem, according to the scientific evidence to date. Lactose intolerance is far from imaginary. I found that the article makes some basic assumptions about lactose intolerance that are incorrect. We always have to start with a few assumptions, and the strength of our conclusions rest on the appropriateness of those assumptions. Finally, I disagree with the central argument of the article, its premises and conclusion.

Self-Diagnosis of Lactose Intolerance

The author states that correctly self-diagnosing yourself with lactose intolerance could be dangerous since it could cause you to ignore other possible, and more serious problems. While I do agree with this, I disagree that the problem is as severe, or likely, as the article suggested, and I disagree with the approach the article takes to make this point, as it presents quite an unclear picture of lactose intolerance. The author seems to be relying much on personal experience:

I went to the doctor and it turns out that in my case there was another illness causing the stomach issues with a transient lactose intolerance as one of the symptoms. Had I just listened to the health gurus, my proper diagnosis might have been delayed.

Again, we have a vague reference to a group of people, "health gurus." So, does this anecdotal experience provide convincing evidence that YOUR lactose intolerance, or what you perceive as lactose intolerance is actually another illness that is causing temporary lactose intolerance? Of course not.

Let's start with the basic observation. You experience the symptoms associated with lactose intolerance after you consume dairy. There is no more a basis for believing you have another serious condition, lets say IBS or Crohn's, than there is for believing you are lactose intolerant. The author makes it seem as if assuming you are lactose intolerant because milk gives you gastrointestinal symptoms is quite a leap, while your having any number of serious diseases is no such leap, and in fact, likely.

Given the information at hand, it is no more unreasonable to assume lactose intolerance than it would be to assume "serious gastrointestinal illness." Either way, you could not be 100 percent sure without a diagnosis.

Many people, still, are reasonably sure about their lactose intolerance. How? Because they have years of experience that lead to them connecting dairy, and the lack thereof, with the presence and absence of symptoms. They have something else on their side. Lactose intolerance is far and away more common than most of the other possible diagnoses, what would be called differential diagnoses by a physician.

However, the problem, according to the article, is this:

Telling people that they are lactose intolerant seems to be a cornerstone of many nutritionist’s advice for a happy and long life with less farting and bloating. Stop consuming lactose and all your bodily issues will be solved.

I am not aware that MANY nutritionists tell people they are lactose intolerant and recommend that they stop consuming lactose altogether, and that this is a cornerstone of their practice. Is this a big problem? Or is this itself a small (but perhaps growing) trend? As I've already pointed out above, "Nutritionists" do not represent a specific professional group. There are all kinds of people, practicing all kinds of things, who call themselves nutritionists. The reference is too vague to be of much use.

Perhaps the biggest problem, as the NIH contends, is not nutrition experts insisting that everybody should avoid lactose, but the self-diagnosis of lactose intolerance when it is unwarranted, which the article also mentions. Many people assume, as well, that they inherited lactose intolerance from a parent who inappropriately labelled themselves lactose intolerant. However, and I'll go deeper into this later on, identifying that there is a potential problem does not tell us the extent of the problem, or even what the specific consequences to public health may be. The article in question seems much more assured of the problems and their extent than is warranted by the information we have.

The Symptoms of Lactose Intolerance Occur Shortly after Dairy Consumption

As you know if you've read through the article here at GUS which I linked in the opening paragraph above, lactose intolerance is not an allergy, and besides the aggravation and discomfort, there are not a lot of other repercussions unless it begins in infancy, which could cause all sorts of problems including "failure to thrive" since an infant gets all its nutrition from breast milk, or often from milk-based formulas. Even so, infant lactose intolerance is not a cut and dry subject, and it is well beyond the scope of this general informational article. Lactose intolerance, gluten intolerance, and various food allergies are quite different. A person is lactose intolerant would probably not continue consuming dairy in large amounts. However, it is possible that a person who was unaware of their lactose intolerance, and who kept consuming dairy and suffering the consequences, might damage their gut, causing continued problems.

Here, I will state a general premise that I will return to several times in this article. The reactions that lactose intolerant people have to ingesting lactose are not all that vague. People who think that they are lactose intolerant because of reactions that occur shortly after consuming dairy aren't reacting to some vague discomfort or sense or malaise, such as those that plague people with imaginary gluten intolerance, or other made up dietary restrictions, people who I and others sometimes refer to as the "worried well." Bloating, pain, gas, and diarrhea are fairly clear-cut symptoms, even if they are common among other illnesses.

Perhaps Zakrisson does not understand that the symptoms that many lactose intolerant people suffer do not leave a lot open to interpretation. You drink milk, and half an hour to a few hours later, you experience several gastrointestinal symptoms. If this happens often enough, most of us would feel reasonably secure in making a causal inference, especially if we were symptom free as long as we reduced or avoided dairy. If, on the other hand, we had many of the same symptoms regardless of whether we consumed dairy, would we not seek out an alternative explanation?

What are the Potential Problems Associated with Self-Diagnosis of Lactose Intolerance?

Therefore, is there an epidemic of people eliminating dairy because they think they are lactose intolerant, who are actually suffering from some other ailment? Is there supposed lactose intolerance keeping them from a proper diagnosis? Before I continue, I should differentiate the two different problems that may be associated with dairy restriction, in case it is not already clear to you:

1. Restricting dairy because of a self-diagnosis of lactose intolerance could cause you to be unaware of another illness that is producing similar symptoms.

2. Restricting dairy, for whatever reason, could pose a public health problem, because of the potential for calcium or vitamin D deficiencies. How likely is this to be a problem?

How Might You Diagnose Yourself with Lactose Intolerance?

Let us suppose you suffer symptoms that you think might be caused by lactose intolerance. Most people with a normal diet might consume dairy many times during the day, in many different forms. If the symptoms occurred often enough after ingesting dairy, and were diffuse enough, this person might react by, at first, completely eliminating dairy, to the extent possible. Now let's say this person was actually suffering from IBS, and it had nothing to do with dairy. What could we expect to happen, once this person eliminated dairy? There may be a small improvement (for reasons we will see later), and there may be no improvement at all.

It should not take long for the person to realize, indeed, that lactose is not the culprit. Supposing this person then seeks out a medical opinion, should we then throw up our hands and say, see, lactose intolerance is a dangerous trend! I should say not, since, in reality, the experience changed very little about the outcome. It simply delayed diagnosis by, perhaps, a week. Meanwhile, there really was a pretty good chance that lactose was the problem. After all, lactose intolerance is not uncommon.

So, I ask, again, is this a huge problem? We could expect most people, as I said, to make a simple causal inference:

"If I consume milk or dairy, I will have bloating, pain, gas, and other symptoms because I am lactose intolerant."

If they then avoided lactose for a period of time, and found that these symptoms did not go away, would they then infer that they were somehow consuming lactose accidentally? Would their lactose intolerance cause them to disregard the possibility of other illnesses?

Furthermore, do most people who identify as lactose intolerant make this leap after one bout of symptoms, so that they are incorrectly diagnosing themselves as lactose intolerant when in fact they have another illness causing temporary lactose intolerance? The article seems to assume this and more. A basic assumption seems to be that many people quickly diagnose themselves with lactose intolerance with very little evidence. There is no indication that this happens so very often that a public health outcry should be mounted. However, if there is a widespread practice in the nutrition and health industry of telling everyone they are lactose intolerant, this may begin happening more often. Again, I have seen very little indication that this is a big problem, as well.

Do the Lactose Intolerant Have to Completely Eliminate Dairy?

Do most people who think they are lactose intolerant completely eliminate lactose from their diet? There is no evidence to suggest this. This could be true of many people, but really, we don't know how people manage their lactose intolerance, real or not. It is simply too hard to pin lactose intolerance down.

Informally, most people who identify as lactose intolerant feel comfortable with consuming small amounts of dairy now and again. They do not worry unduly about dairy in their diet unless the problem is quite severe, as they know the symptoms are temporary even if they should consume more than they can handle. As well, unlike the TV version of lactose intolerance, it does not send you racing to the bathroom minutes after you've had dairy. Symptoms may not occur until an hour or even several hours later.

What Causes Lactose Intolerance?

About the cause of lactate intolerance, the article states:

If there is not enough lactase sitting around in your intestine, the lactose molecule cannot be broken down and this can irritate the intestine and cause painful bloating, diarrhea and stomach cramps.

Lactase enzyme doesn't exactly sit around in your intestine. Lactase enzyme is produced by the the mucosal epithelial cells of the small intestine, just as other enzymes, like peptidase, maltase, and sucrase, are produced by cells that line the intestine. When those cells do not produce enough lactase, for whatever reason, lactose does not get broken down, but passes through the gut undigested (a very small amount of whole lactose may actually be absorbed, but not enough to matter). The presence of lactose itself in the gut is not known to cause a reaction or to directly inflame the gut. Instead it is the bacterial fermentation producing gas and acid that leads to discomfort and irritation.


More specifically, to be absorbed by your gut, lactose must be broken down into the monosaccharides glucose and galactose. When lactose is not broken down, and it passes through your intestine, this draws water into the intestine, causing diarrhea. At the same time, bacteria go to work on the lactose, and these bacteria produce gas which bloats you and volatile fatty acids which irritate your gut.

Factors Influencing Timing and Severity of Symptoms

However, whether or not symptoms will occur, their severity, and their timing depends on several factors:

  • The presence and amount of lactase enzyme
  • The amount of lactose ingested
  • The form in which it was ingested (is it cooked in a dish with other ingredients?)
  • The fat content of the milk
  • Gastric emptying determined by meal composition
  • Intestinal transit time (how slowly or quickly it passes through the gut)
  • Intestinal secretion in response to the osmotic challenge (more or less water absorbed into the gut in response to the undigested lactose)
  • The bacterial flora population and its capacity to digest lactose.

There are two other factors that are a more psychological than physical, although they can have physical manifestations: The person's sensitivity to the discomfort from consuming lactose, and a person's anticipation of symptoms from having had a bad experience related to milk before. So you see, with all these variables taken into account, the severity of lactose intolerance, and how a person deals with it are not cut and dry!

Temporary Lactose Intolerance

A temporary state of lactose intolerance is possible because of some type of gut infection or inflammation. This is true. It is also true, as the article states, that the symptoms of lactose intolerance are similar to many other GI diseases. If this caused you to permanently conclude that your continuing stomach problems were caused by lactose intolerance, without a diagnosis, this could lead you to ignore other potentially dangerous illnesses. If an irresponsible nutritionist told you to eliminate all dairy to cure your stomach problems, and you were actually suffering from IBS or some other problem, would all the symptoms likely disappear? It seems not. It seems more likely that eliminating dairy would not solve your problem, although it may provide some temporary relief or reduction of symptoms. The symptoms of lactose intolerance are quite intense and they occur very soon after ingestion of lactose (this bears repeating!) Compare this to the vague feelings of discomfort that people experience, then attribute to gluten. There is no comparison! We will go deeper into temporary lactose intolerance, often called secondary lactose intolerance, later.

Different 'Types' of Lactose Intolerance?

This article ignore baseline statistical information. In great majority of the world's population lactase enzyme production is strongest at birth and steadily declines throughout life. Hence, some degree of trouble digesting lactose is to be expected as most people age. Estimates (and they are just estimates) are as high as 75% of human's having some degree of lactose intolerance.

Further confusing the issue, the article asks "what type of lactose intolerant are you?" Using information borrowed from the NIH (National Institutes of Health) and the CDC (Centers for Disease Control), the article presents terms associated with lactose intolerance as if they are "different types" of lactose intolerance. This is not how the NIH/CDC meant for this information to be presented. A cow's milk allergy, although it can be a term associated with lactose intolerance, should not be listed under the heading "what type of lactose intolerant are you," yet it is. Cow's milk allergies have to do with proteins in milk, not lactose. A person with cow's milk allergy who consumes milk could potentially die. A lactose intolerant person will NOT die from consuming lactose.

These terms are confusing at best. The NIH/CDC source material, which is presented verbatim in the article, states that "Lactose intolerance refers to the symptoms that occur in an individual that suffers from lactose malabsorption." To be clear, all lactose intolerance causes "lactose malabsorption," even temporary lactose intolerance. Listing "lactose malabsorption" as if it means something different than "lactose intolerance" simply muddies the picture. All lactose intolerance comes with lactose malabsorption, whether the state is temporary, late-onset, etc.

A congenital lactase deficiency which is present at birth should not be confused with lactose intolerance. This deficiency, which causes severe lactose intolerance in infants is caused by a mutation in the LCT or actase-phlorizin hydrolase gene which is expressed in the aforementioned cells that line the intestine. This genes governs the making of the lactase enzyme. When this gene is faulty, it interferes with the production of lactase enzyme.

For adults who experience lactose intolerance later in life, the gene is fine, it is the expression of the gene that changes. There is another gene nearby the LCT called MCM6. Normally, this gene regulates the expression of the LCT gene, causing it to cease producing lactase enzyme. This causes a lactase deficiency in adult-hood. Some people in the world have a mutated version of this gene, causing them to keep producing lactase enzyme throughout life.

The article claims that lactose intolerance can be genetically caused or be non-genetic due to a secondary cause. Let's look at the terms from the NIH/CDC that the article offers. These definitions are supposed to help us not get too confused:

  • Lactose intolerance - The symptoms you get from lactose malabsorption whether genetic or non-genetic.
  • Lactose malabsorption - Lack of ability to break-down lactose, whether genetic or non-genetic.
  • Lactose non-persistence - Genetic type (of lactose intolerance?) where the lactase enzyme is reduced after childhood and remains low in adults. Often shows symptoms.
  • Lactose persistence - The genetic type (of lactose intolerance?) where high levels of lactase enzyme remain into a adulthood. You have no problems digesting lactose.
  • Cow's milk allergy - An allergy involving the immune system. Mostly occurs in children and often disappears in adulthood. Don't confuse allergy with food intolerance.

Are you confused? I sure am. What is the generally accepted definition of lactose intolerance? Just so you know, there is nothing inherently wrong with borrowing information form the NIH or CDC. It is public domain. Some indication or citation, however, would have been appropriate, so that readers could read the source material for themselves. Much more information is offered in that material. To read it for yourself see NIH Lactase Abtracts. These materials provide much more information on lactose intolerance, including its prevalence and how to manage it while still having adequate nutrition.

Now, let's simplify matters with a more manageable definition of lactose intolerance:

Lactose intolerance is the inability to digest the milk sugar lactose, resulting in a group of various symptoms after milk products are ingested.

There, much more simple. It stands to reason that if you have an inability to digest milk sugar, you will have some degree of lactose malabsorption.

What is Non-Genetic Lactose Intolerance?

Remember above I explain how being lactose intolerance is determined by your genes? So what is this non-genetic version? This is lactase deficiency that is caused by a secondary problem, such as damage to the intestinal mucosa that causes them not to make the enzyme efficiently. This may be temporary. It is often called secondary lactose intolerance, and above, I placed it under the heading temporary lactose intolerance.

I think that the point in the article was to differentiate between genetically determined lactose intolerance and temporary lactose intolerance, but this is not clear and it seems to be trying to underestimate true genetic lactose and overestimate lactose malabsorption due to secondary causes. To be abundantly clear about something I've already stated, lactose intolerance is the most common food intolerance in the world. It is the most common carbohydrate maldigestion disorder in the world. And this is all that lactose intolerance is, the maldigestion of the sugar lactose. The most common form of lactose malabsorption is a genetically determined reduction in enzyme activity in adulthood. Just as explained above. In general, lactase enzyme starts slowly declining from age 2 to 5.

Next, the article correctly states:

The most common form of lactose malabsorption is called lactase non-persistence and means that the lactase enzyme levels slowly decreases in concentration as the infancy-period comes to an end. The lactase enzyme does not persist into adulthood (hence non-persistence).

In people with lactose persistence, however, the enzyme remains at high concentrations into adulthood. In some populations like in Scandinavia (where I am from), the persistent phenotype (the genetic type that expresses lactase in adulthood) dominates, thus making the population overall less sensitive to lactose.

However, the conclusion seems to be a leap:

Hence, it is incredibly stupid to come up with recommendations regarding dairy products that cover too many ethnic groups. Milk can be anything from a fantastic source of protein and nutrients (and good taste) to a source of pain and discomfort. It depends on who you are.

Who is it that is making these incredibly stupid recommendations? What person or persons? What sources? What organization? No citations are given as to the origin of these statements, and vaguely citing a group of widely scattered professionals is not a citation at all. Indeed, people in Scandinavia have a very low incidence of lactose intolerance and this information is quickly available to anyone who cares to look. Estimates are that only around 3% are lactose intolerant.

Yet, as the author brings up different ethnic groups, she makes no mention of the actual numbers. Those numbers indicate that in MOST ethnic groups, the majority of people are lactose intolerant! There is a huge difference between someone suggesting that a Southern Italian, for example, might be lactose intolerant, and suggesting that a Scandinavian might be. Up to 71% of Southern Italians are lactose intolerant.

Again, who is it that is coming up with recommendations regarding dairy products that cover too many ethnic groups? Is this a common problem in the medical establishment? Among credible nutrition and other health sources? My research into this article and others does not indicate such general recommendations.

Furthermore, the preceding paragraphs state that the most common form of lactose intolerance is called lactase non-persistence (it actually goes by many names, including developmental lactose intolerance, adult-onset lactose intolerance, late-onset lactose intolerance, etc.), but the author then fails to consider the prevalence of lactose non-persistence to lactose persistence.

At a casual glance, it would appear that you are just as likely to be lactase persistent as you are to be lactose non-persistent. Yet, among humans in general, without knowing anything else, you are more likely to be lactose non-persistent. While there may be some quacks that are recommending whole-scale a lactose-free diet to any and all comers, this is nowhere near a problem on the scale of some dietary adherence trends, and the reasons that various quacks have for telling people to eliminate dairy are varied, lactose being one in many.

How Common Is Lactose Intolerance? It it Really a Trend?

The incidence of lactase intolerance in the U.S. has been claimed, according to studies, to be over-estimated, however, it is not clear whether it is the incidence of lactase non-persistence that is overestimated, or simply the incidence of problems. In other words, the symptoms experienced after lactose ingestion, and the amount of lactose needed to produce these symptoms, are quite variable, as I explained above. Quite normally, those who are 'lactose non-persisters' can tolerate up to 6 grams of dairy with little problem. It could be that a great mean lactose non-persisters are symptom free, also. In other words there could be more lactose non-persistent people than lactose intolerant people.

I'll break it down the incidence among ethnic groups a little further, but keep in mind that these numbers are subject to revision when better studies are carried out:

Prevalence of lactose intolerance among various ethnic groups:
Native Americans: 80%
Southeast Asians: 80% (Asians in general - 90% at least)
African Americans: 65 to 75%
Mediterranean regions: 70%
Hispanics: 50%
Northern Europeans: 10%
Inuits: 60%
Caucasians (in general): 20%

So, you can see, it's safe to say that lots of people are lactose intolerant. Even among those who are actually diagnosed with lactose intolerance, using a breath test, complete elimination is not usually necessary. While it may be that some "nutritionists" are writing books or articles recommending lactose free diets and overstating the problem and its solutions, this "trend" does not mean that lactose intolerance and everyone who limits dairy to some extent due to the perception, for whatever reason, that they are lactose intolerant, are subject to this trend.

Indeed, credible dietitians or doctors who understand what lactose intolerance is, and how variable it is, would not just automatically recommend total elimination of all dairy. So, while nutritionists who do this are quite wrong, it is a stretch to thereby declare that lactose intolerance is just a fad. It's more than a stretch. It is a ridiculous claim. In case I have not stated my case abundantly already: Dairy elimination is a fad. Lactose intolerance is not a fad.

What are the Causes of Secondary Lactose Intolerance?

What of the various causes of secondary lactose deficiency? Well, the lactase enzyme is expressed at the tip of the the epithelial cells in the gut. Any damage to any area of the gut therefore effects the amount of lactase enzyme you produce. The article states that such lactose intolerance is then temporary, and will go away after the illness is gotten under control, or is cured. Although this is usually true, lactase intolerance may actually persist for months even after healing. For example, bacterial overgrowth could cause the symptoms of lactose intolerance, even though there is no longer a lactose deficiency.

A cow's milk allergy could cause a secondary lactase deficiency and this is due to gut damage after reactions to the offending protein in milk. Milk is made up of two different proteins, casein and whey which have different protein factions. People can be allergic to any one of several of these proteins, and there are some that are common allergens. Ingesting these proteins can cause irritation to the gut, but this is an allergic reaction to the proteins, not a maldigestion problem, as is lactose intolerance. A soy protein sensitivity, by the way, could cause similar problems.

You wouldn't likely mistake a cow's milk allergy for being simple lactose intolerance, so, what are some of the other possible causes of secondary lactase deficiency besides a cow's milk allergy?

  • Viral, bacterial, or parasite related gastroenteritis
  • Giardia infection
  • Crohn's disease
  • Chemotherapy
  • Radiation therapy
  • Bacterial overgrowth
  • Severe malnutrition (brush border enzymes are diminished with severe malnutrition, causing lactose intolerance, which will normalize after proper dietary nutrition is resumed)
  • Short bowel syndrome
  • Celiac disease (especially in newly diagnosed patients)
  • HIV

Crohn's is a pretty serious illness. Regardless of ethnicity, in the U.S. what is the prevalence of Crohn's? Well there are about 26 to 199 cases per 100,000 persons. In other words, the it is not really extremely likely that your self-assessment of lactose intolerant is hiding Crohn's. You could ask similar questions of other common secondary causes. The most significant and prevalent secondary cause, or differential diagnosis is IBS, or irritable bowel syndrome.

The Medical Diagnosing of Lactose Intolerance

Up to this point, I have only briefly mentioned diagnosis. I said that one way to confirm lactose intolerance was with a type of breath test. Then, I said that most people, if they think that dairy is causing their problems, and they may be lactose intolerant, will informally eliminate dairy for a while to see if their symptoms go away.

I've saved for last something that may surprise you. The "definitive diagnosis," the breath test that Zakrisson insists everybody get, is not routinely ordered in the U.S. without first using an elimination and then challenge dose of lactose to at least see if lactose intolerance is suggested. Why order expensive or even invasive tests without first getting a better idea if it is a possibility? The idea that you will go to the doctor, explain your symptoms, and immediately be administered a breath test is probably not likely. Diagnosis requires a nutritional, medical, and family history. Do the symptoms occur every day? Do they get worse as the day goes on? Are they associated with mealtimes? All these are among the many questions they may be asked.

If lactose intolerance is suggested, what kind of tests can be used to confirm it?

Breath Hydrogen Test of Lactose Malabsorption

The most simple and noninvasive test, and the one that is generally preferred, it the Breath Hydrogen Test, which has been mentioned several times in this article. This test checks for lactose malabsorption. The patient is administered a load of lactose (1-2mg/kg up to 50g total)1 and then hydrogen in the breath is measured. If the amount of hydrogen in the breath rises by 20 parts per million or more above the baseline, the test is positive. One breath test is administered before the lactose, and then further tests are administered every 30 minutes for the next 3 hours after lactose is ingested.


Something you should be aware of is that the diagnosis of lactose malabsorption does not really predict whether you will have symptoms, how severe they will be, and how much dairy you can or cannot tolerate. This same test is used to determine other forms of carbohydrate maldigestion and malabsorption. It can also suggest bacterial overgrowth in the small bowel, and if this is present, it could cause a false positive.

Oral Lactose Tolerance Test

This test measures plasma glucose levels after a challenge does of lactose is given. This test requires fasting and the avoidance of any strenuous activity for 8 hours before the test. A blood sample is taken for baseline reference, and then a large dose of lactose is given, such as 50 grams for an adult. The patient is observed for symptoms, and blood samples are drawn after 30 minutes, one hour, and two hours. All the blood samples will be send to a laboratory to test the plasma glucose level. This is test is similar to a glucose tolerance test. Normally, plasma glucose levels are expected to rise more than 20 mg/dL after the lactose-loading dose is given. This test takes a lot of time, can be uncomfortable due to the large unphysiological dose of lactose used. It was used more in the past but today the breath hydrogen test (above) is more preferred.

Endoscopic Intestinal Biopsy

This test is now considered obsolete, at least in the U.S. and, it appears, in the U.K., but it bears mentioning. Intestinal biopsy samples using an endoscopic procedure would be taken for the purpose of histologic examination and a lactase enzyme activity assay. This is, obviously, very invasive. As well, it is not necessary for the gut to be completely unable to produce lactase for some degree of lactose malabsorption to be present. Lactase deficiency in the gut may be patchy, because mucosal injury may be patchy. This test would not rule out secondary lactose intolerance. It is too costly, too time consuming, and too invasive to be considered appropriate for the diagnosis of lactose intolerance.

Stool Acidity Test

This test, also, is of limited efficacy. When lactose in the gut is subject to bacterial fermentation, lactic acid, and, as mentioned before, short-chain fatty acids are produced. Normally, stools are alkaline, when there is more acid in the stool due to the lactose fermentation, the pH rises. A pH of 5.5 or less is considered abnormal. The problem with this test is that it is not specific for lactose intolerance and could intake other carbohydrate malabsorption disorders.

Genetic Test

Now, you may be thinking, with all these diagnostic tests, why bother with a genetic test? Well, none of the other diagnostic tests actually show the cause of the lactose intolerance. You could "test positive" for lactose intolerance and have it be temporary, for instance, due to it being a secondary consequence of an simple intestinal virus. It could also be secondary to other diseases. It would be much better to be able to predict the presence of lactose intolerance by testing at the genetic level.

There is not a proprietary genetic test which specifically identifies patients with the genetic biomarker associated with low levels of lactase due to lactase non-persistence. This test, developed by Prometheus Inc. is called the PRO-GenoLogix Lactose Intolerance test. It will show clearly whether lactose lactose intolerance is to be expected and it will differentiate it from other diseases with overlapping symptoms, and from secondary lactose intolerance due to any cause. It is noninvasive, requiring just a blood test. There is no need to fast, or to take take a huge amount of lactose, and it doesn't take several hours.

What of these other diseases? Perhaps more information is necessary.

IBS and Lactose Intolerance

I've already mentioned that the most likely condition to be mistaken for lactose intolerance, is IBS (Irritable Bowel Syndrome). Zakrisson, in her article, makes a lot of the potential to ignore other disease due to failing to get a medical test, thinking you are lactose intolerant. Yet, IBS, the most common condition that can present with the same symptoms, post-meal abdominal pain, diarrhea, and bloating, although affecting up to 10 to 15% of the U.S. population, currently has no reliable diagnostic biomarker. The diagnosis is based on symptoms. Are you putting this together? The differential diagnosis of IBS is no more a sure thing than a symptom based diagnosis of lactose intolerance, and yet it is a simple matter to associate the symptoms of lactose intolerance with dairy, whereas IBS symptoms can tend to occur after various types of meals and it is much more difficult to pin down the offending foods. Lactose malabsorption seems to be more common in IBS sufferers, and the symptoms due to lactose ingestion tend to be worse. IBS does not always present with diarrhea, though, constipation may also be present. Therefore, IBS with diarrhea is part of the differential diagnosis with lactose intolerance, and vice versa.

Inflammatory Bowel Disease and Lactose Intolerance

IBD stands either for inflammatory bowel disease. Primarily, two diseases are related to IBD: ulcerative colitis and Crohn's disease. However, microscopic colitis is also possible. Although the same symptoms of lactose intolerance can be present with these diseases, patients often present with bloody stools, weight loss, and anemia. Microscopic colitis, both lymphocytic and collagenous colitis can present with symptoms similar to lactose malabsorption, but these are more common in middle-age patients and occur more often in women than men.

Celiac Disease and Lactose Intolerance

True celiac gluten intolerance, which is an immune response to gluten in the bowel, often presents with symptoms similar to lactose intolerance. Since celiac disease can damage the gut, secondary lactose intolerance can occur. However, lactose intolerance due to lactose nonpersistance may also be present, as it is common. People newly diagnosed with celiac often are lactose intolerant due to a temporary lactose deficiency in the gut. Should a person develop symptoms after consuming milk, should they then be checked for celiac? Probably not. It would be more appropriate to see if symptoms improved after a period of dairy avoidance and then re-introduction. It is up to your doctor to determine the appropriate diagnostic course.

Food Intolerances Other Than Lactose (FODMAP)

Symptoms similar to lactose intolerance can be produced by an intolerance to other foods, such as foods that contain fructose, sorbitol, and fat. In particular, fructose malabsorption can lead a similar osmotic effect as that of lactose, causing water to be absorbed into the small intestine and resultant diarrhea. Bacteria can also ferment fructose, with effects similar to those of the fermenation of lactose. In patients with IBS-like symptoms, the efficacy of a food-restriction diet called FODMAPS (ermentable oligosaccharides, disaccharides, monosaccharides, and polyols), which includes fructose and other short-chain carbohydrates. More evaluation is needed with larger studies, and these are ongoing.

There are other dietary components, such as wheat, that have been associated with IBS in studies as well, leading to a hodgepodge of definitions and food-restrictions diets. Just as there are many gluten-free diet books on the market, so there are many FODMAP diet books. If each type of restriction associated with IBS was adhered to, eating would become almost an impossible task, unless one decided to eat hardly anything but meat. This has lead people to adhere to some highly restrictive versions of Paleo and other diets. The many dietary strategies that have grown out of various studies have built a confusing puzzle that needs to be unraveled before effective and realistic dietary interventions can be developed. FODMAP diets do seem generally helpful in managing IBS, but they are not all created equal and some may constitute inadequate nutrition.

How Does All This Stack Up?

The article "Am I Lactose Intolerant" makes it seems like people routinely declare themselves lactose intolerant after experience gastrointestinal distress, and then enter into an ill-advised dairy-elimination diet. They then fail to consider other diseases that could be mistaken for lactose intolerance. What the article leaves out is that these other diseases, explained here in some detail, make up part of the differential diagnosis for lactose intolerance, which is considered when dairy cannot be cannot be consistently linked to symptoms.

If you and your doctor suspect lactose in the cause of your symptoms, your doctor may well suggest some period of avoiding lactose. After avoiding dairy for a certain period of time, say a week, to see if the symptoms do not re-occur. Then after a certain period of avoiding lactose, the doctor will have you do a "lactose challenge" to see if the symptoms re-appear. If at that time the symptoms occur, and this can even be repeated to see if a consistent link between lactose and discomfort can be established or not established. In making it seem as if linking the consumption of dairy to GI symptoms, and then considering this link to be suggestive of lactose intolerance is a crazy idea. It's not.

Even if another diagnosis is proper, such as IBS, lactose can still present a problem. This is another problem with the over-stated tone of the article. It is not either you are lactose intolerant or you have some other disease. You may have, in fact, other problematic foods, and one problem may well lead to the next.

Although the NIH/CDC has asked questions about the dietary health consequences of eliminating dairy due to lactose intolerance, and provided information on differential diagnoses, etc. I can assure you that it does not say that lactose intolerance is a "dangerous fad." It also provides no information as to a widespread practice of advising people to eliminate dairy haphazardly due to lactose intolerance.

Do I agree that everyone should seek out proper diagnosis of the cause of their gastrointestinal distress, even if they are pretty sure it is linked to milk? Yes. I agree that this is important. However, I do not believe that to get people to do this, it is necessary to make unreasonable claims about the severity of the problem. What is more important is education. The message is, yes, your symptoms may be lactose intolerance, and they may not. To treat lactose intolerance as if it is a phantom, while illnesses like IBS should be upper-most in your mind, is just silly.

If you consistently notice that you have the symptoms described here after you consume milk or dairy products, such as abdominal pain, bloating, flatulence, and diarrhea, there is nothing wrong with deciding to avoid dairy for a while. During this period, watch for symptoms after your dairy-free meals. Are you still experience symptoms? If so, then lactose intolerance is not your problem. If symptoms to not occur, then, after a week or two, you can try some dairy again. For example, you can drink a big glass of milk. Then, if the symptoms occur again, you could tentatively suspect you are lactose intolerant. You could even repeat this whole thing.

Even if you don't go to the doctor, you could use this information and seek out information on how to manage lactose intolerance, which does not necessarily require total elimination of dairy. You will likely be able to tolerate small amounts of dairy. As well, some people find that if they gradually introduce and increase the amount of dairy consumed, they begin to tolerate dairy much better. Also, certain dairy products are often more tolerated by lactose intolerant people such as cheese and yogurt.

Let's say you try to control your symptoms by controlling your dairy consumption, and you make sure to eat a varied diet with adequate levels of calcium and vitamin D. What harm is likely to come to you? You didn't go to the doctor, but you symptoms are either gone or happen infrequently, are not as severe, etc. What if you explained this to your doctor after you had already learned to manage your "lactose intolerance?" Do you think your doctor would throw up his or her hands in exasperation and declare you an idiot for failing to get a medical test? Most probably not! More likely, your doctor would advise you to continue what you had been doing and to report any changes, should they occur.

IBS Research Actually May Have Led to a Dairy Elimination Fad

IBS itself, the most common differential diagnosis, is also often self-diagnosed. It is also frequently diagnosed by unqualified practitioners like naturopaths, assorted nutritionists, and "wellness" experts. What is more, it is very difficult to definitively diagnose in a true medical setting. There are even those who doubt its validity. Ironically, it is research into potential dietary factors in IBS or IBS-like symptoms that have given rise to these unqualified health practitioners advising all sorts of dietary restrictions, including lactose. In other words, it is the true research into causes of one possible differential diagnosis of lactose intolerance, and a cause of secondary lactose intolerance, that has led, in part, to this so-called lactose intolerance fad.

Imagine if I had written an article saying, all these quacks telling everyone they have IBS may cause them to disregard their lactose intolerance! You see? These other diseases seem like bigger "boogeymen" than lactose intolerance. There is no call, therefore, for saying that lactose intolerance is a silly fad, and unlikely. It is real. And it is likely. Other conditions may be possible. So, if you have continuing symptoms seek out proper diagnosis and nutritional advice on how to manage whatever condition you may have. Do not needlessly eliminate dairy from your diet.

In Conclusion

Instead of advising people that lactose intolerance is just a silly fad, and to not eliminate dairy, I think people should simply be advised to ask their doctor, and that they should be advised on ways to manage lactose intolerance, without eliminating dairy completely. This is certainly possible for many people. Or, if they choose to avoid dairy (its quite difficult to eliminate), advise them on good sources calcium, protein, etc. Also, although the article equates commercial lactase enzymes like Lactaid to consumer ripoffs, for those who really need them and can afford them, they work. You can read more about these in this article.

People are being advised to eliminate dairy for many other reasons than lactose intolerance. A common reason is "humans were never meant to consume the milk of another species." What is the fad, if a fad exists? It is dairy elimination out of the mistaken notion that "dairy is bad for humans." Lactose intolerance may be a reason to restrict dairy, and for some with severe problems, eliminate dairy, but this does not make lactose intolerance itself a fad. Lactose intolerance is very common in humans, and you would not be a fool to think that your re-curing symptoms after consuming dairy are caused by lactose intolerance.

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