NIH Conference Report on Lactose Intolerance and Health

Yeah, I know that I already did a 28-part series on this. However, I wanted to get the official journal citation onto the record.

The summary statement from the National Institutes of Health Consensus Development Conference: Lactose Intolerance and Health by Frederick J. Suchy et al. was published in Annals of Internal Medicine, June 15, 2010, vol. 152 no. 12 792-796. Full text at: http://www.annals.org/content/152/12/792.full.pdf+html.

Report from the LI Conference, part 28: Question 4 Summary

The NIH LI Conference draft report summaries the presentations from Newberg, Sanders, Keith, Gordon, Shaukat, Johnson, and Taylor to answer question 4.

What are the future research needs for understanding and managing lactose intolerance?

Reliable estimates of the U.S. prevalence of lactose intolerance and lactose malabsorption are not available in a representative population of diverse ages and races/ethnicities. Most of the available research assessed subjective symptoms in an unblinded fashion in selected groups of subjects or in individuals unable to fully absorb lactose irrespective of symptoms of lactase nonpersistence. Therefore, we recommend that a study be conducted to determine the prevalence of lactose intolerance in the U.S. population and the differences across age and racial/ethnic groups. The study should examine a representative sample of the U.S. population and determine the following:

• The prevalence of self-reported baseline symptoms
• The prevalence of lactose malabsorption with or without symptoms following a blinded lactose challenge
• The relationship between self-reported symptoms and the presence of lactose malabsorption
• The prevalence of lactose intolerance in those individuals with lactose malabsorption based on the blinded challenge.

The best approach to minimize placebo effects is to conduct blinded challenges using a standardized, taste-masked dose with and without lactose and to define symptoms using a well validated scoring system. Studies on what constitutes an optimal challenge dose of lactose also should be conducted. Dietary history regarding lactose consumption and symptoms associated with polymorphisms affecting lactase gene expression potentially could obviate the need for taste-masked, blinded oral challenges with lactose and placebo. An opportunity exists to use the infrastructure of the ongoing National Health and Nutrition Examination Survey or other ongoing nationally representative studies, which already are collecting dietary intake data and would allow additional and potentially informative evaluation of the intake of lactose-containing foods in those with rigorously determined lactose malabsorption with or without symptoms.

Despite the widespread belief that decreased vitamin D and calcium intake associated with restricted intake of dairy products will lead to poor health outcomes, particularly related to bone mineral density and risk for fractures, few data are available on bone health in individuals with lactose intolerance and dairy avoidance. Future studies should investigate the association between dietary calcium intake and outcomes in people with lactose intolerance on low-lactose diets. A diverse population should be evaluated including children, the elderly, males and females, members of ethnic/racial subgroups, and those with susceptible genetic polymorphisms. The latter genetic alterations should include potential modifying genes. Also, the efficacy of dietary calcium intake from nondairy products and from nutritional supplements should be examined in relation to bone health and as to whether other foods influence calcium absorption from these sources.

Although puberty is the period of most rapid accrual of bone mineral, studies are needed to determine whether calcium intake during this period will affect the subsequent risk to develop osteoporosis. Other health outcomes including obesity, diabetes, cardiovascular disease, and cancer also should be assessed in individuals with treated and untreated lactose intolerance and in other individuals avoiding milk products because of perceived lactose intolerance in comparison with the general population. Additional issues of importance need to be addressed in children with lactose intolerance through long-term observational studies and randomized controlled clinical trials of various treatment strategies. These issues include the incidence of infection, allergic disease, and standard measures of growth and development.

Data are lacking as to whether individuals of different races/ethnicities, ages, and genders who have lactose malabsorption have differing tolerance to lactose. Blinded, randomized controlled trials are needed to determine if the quantity of lactose that can be tolerated by lactose-intolerant individuals varies by race, ethnicity, age or gender. Symptoms should be reported in a standardized, validated format so that clinically important differences can be appreciated.

The lack of uniformity in study design and methodology hampers a rational, evidence-based approach to management of lactose intolerance. Defining the tolerable dose of lactose in those with lactose malabsorption is critical to determining the clinical importance of lactose malabsorption and the prevalence of lactose intolerance, and it may provide critical information for management. A stepwise approach should be developed to define the specific amount of dairy foods to introduce to the individual with lactose intolerance (i.e., the greatest amount of lactose that is not associated with symptoms). Studies also should be conducted to confirm whether lactose is better tolerated if distributed throughout the day or given with meals. Some individuals have reported moderate value in reducing symptoms by using lactase or lactose-hydrolyzed milk; however, sample sizes and the reporting of symptoms were so variable in reported studies that making firm recommendations is difficult. The use of prebiotics (a nondigestible food component, usually a carbohydrate, which benefits the recipient by promoting intestinal colonization by beneficial bacteria) and probiotics in dietary supplements and foods including yogurt is a popular intervention for individuals with lactose intolerance, but further studies are needed to document the efficacy of such products in reducing symptoms. Calcium intake from low-lactose dairy products, nondairy products, and nutritional supplements is an alternative management strategy in individuals with lactose intolerance, but few data are available on the effect of such interventions on individual outcomes, including bone mineral content and fractures.

It will be important to determine whether testing for lactose malabsorption will change the behavior of individuals who avoid dairy products, many of whom may not have lactose intolerance. Future research should employ standardized interventions, blinded controls, and reporting of improvement of symptoms in a consistent, validated fashion to compare the efficacy of these dietary management strategies in obtaining clinically meaningful health outcomes.

Once effective interventions have been identified, behavioral and culturally sensitive approaches to convince people to adopt recommended dietary changes should be developed and tested. Clearly, the perception of symptoms in individuals with lactose intolerance may be highly subjective and very susceptible to a number of psychological and cultural factors. Thus, various strategies may result in very different behavioral changes, and their effectiveness should be compared rigorously.

Additional work needs to be done to improve the management of patients with irritable bowel syndrome and a hypersensitive colon who also may have lactose intolerance.

Report From the LI Conference, part 27

Part 27. Hey, I sat there for a day and a half. Think how I feel.

Anyway, this was the last presentation.

Psychological Impacts: Strategies Effective in Managing Individuals Diagnosed With Lactose Intolerance
Janet E. Taylor, M.D., M.P.H.
Psychiatrist
Private Practice

Dr. Taylor wrote that "Undiagnosed individuals with gastrointestinal complaints may present with somatization preoccupation." How many of you out there know what somatization preoccupation is? If you do, you were one up on me. I had to look it up.

Somatization disorder refers to the preoccupation with multiple physical complaints suggestive of a somatic disease for which a clear physical etiology and an adequate medical explanation cannot be found.

In shorter words, you're sick with a real physical, as opposed to psychological, disease but no one can tell you what you have. Lactose intolerance should be easily diagnosed, but often isn't. And many people have a range of gastronintestinal disorders that may overlap with or be confused with or be suffered in addition to LI. I also have irritable bowel syndrome, and needed to find a treatment for that before my intestinal complaints could be brought under control.

Disorders that aren't quickly and properly identified lead to long-term distress of many kinds. More suffering, more sick days, more disruption. The psychological complaints that you didn't have in the beginning, like depression or anxiety, can result from not having the physical side go untreated.

Physicians have to become more aware of these psychological issues and look for signs of them and learn how to treat them as well as the physical illnesses.

There's more.

Here's a real problem that is almost never talked about when health is being debated. As many as 30% of adults in this country are functionally illiterate. They read at a fourth grade level or less. They may not know basic terms like "serving" or "calcium." They're probably not reading blogs, much less books or medical journals. The nutrition information on a package is probably confounding. The list of ingredients may not be understandable. They may not go regularly to doctors and if they do they're probably more concerned about other, urgent, health care needs.

I'm addressing this blog to a literate, probably well-educated population. That turns out to be only part of what needs to be done. All of the people in the U.S - and elsewhere - need the best health and the best information to achieve it, not just 70%. If you have any ideas on how that might be possible, please let me know.

Report From the LI Conference, part 26

We're back to another round of lactose intolerance influences people to not have dairy which lowers their calcium intake which has long term effects. The difference here is that Dr. Johnson looked at people's feelings as well as their behaviors.

Behavioral Factors Related to Lactose Intolerance and Bone Consequences
Susan L. Johnson, Ph.D.
Associate Professor
Department of Pediatrics
Section of Nutrition
University of Colorado Denver
Anschutz Medical Center

Most Important Problems Encountered With Having Lactose Intolerance

1 Not able to eat certain foods that you like

2 Worry about embarrassment at social events because of lactose intolerance

3 Limit your physical activity because of lactose intolerance

4 Concern about not getting enough calcium

5 Concern about developing osteoporosis or other bone diseases

6 Limit activities that take you away from available restrooms

The perceived inability to eat certain foods goes directly to milk drinking. Some people avoid all dairy products because of LI. But realistically, people don't stop eating their favorite foods like cheese, especially on pizza, and ice cream even if they are LI. That's probably why lactose-free ice cream never breaks through in the market.

One thing that's not known and would be helpful is whether adult perceptions of foods that "can't" be eaten because of LI affects the views of their children. Some children, especially Hispanic girls, were more likely than others to think of themselves as LI and so avoid dairy. If milk can be added to breakfasts, however, it's more likely to be drunk.

Report From the LI Conference, part 25

Another member of the thundering herd from Minnesota gave one last presentation that combed through the medical literature pertaining to this question.

Evidence-based Practice Center Presentation IV: Effective Strategies for the Management of Individuals With Diagnosed Lactose Intolerance
Aasma Shaukat, M.D., M.P.H.
Investigator
Minneapolis Veterans Affairs Medical Center
Division of Gastroenterology
Department of Medicine
University of Minnesota

The literature burped up a grand total of 37 studies for managing lactose intolerance. Almost all of them showed nothing of interest or were based on such small and bad samples that they added up to nothing.

The limp conclusion: using lactose-reduced milk reduced symptoms in the lactose intolerant.

Report From the LI Conference, part 24

A lot of good stuff in the next presentation, so let's jump right in.

Treatment Recommendations in Children
Catherine M. Gordon, M.D., M.Sc.
Director
Children's Hospital Bone Health Program
Adolescent/Young Adult Medicine and Endocrinology
Children's Hospital Boston
Associate Professor of Pediatrics
Harvard Medical School

A big question that I haven't seen answered before is whether avoiding dairy - and not making the effort to replace the calcium that would be found in a dairy heavy diet - really makes a difference to health.

There are a few studies which say that not having dairy hurts your bones. And generally speaking, we can say that people who know they are lactose intolerant (LI) have less dairy - if any at all - than people who don't consider themselves to be LI. Vertebral fractures are higher in people with LI. Bone mineral density is lower, and the more severe the symptoms reported the lower the density became. This started to be true even in a population of girls aged from 10 to 13. If children aren't having dairy, they are highly unlikely to do so later in life.

How to get more dairy into your diet if you have LI? Here are several suggestions.

1. Consume small amounts of lactose-containing foods.

2. Chronic/repeated intake of lactose-containing foods allows colonic bacteria to adapt and more efficiently metabolize lactose.

3. Co-ingest lactose-containing foods with a meal.

4. Consider the form of the lactose-containing food. Hard cheeses, chocolate, higher fat milks, and ice cream are well tolerated.

5. Eat live culture yogurt.

6. Utilize commercially available lactose digestive aids.

7. Modify behaviors and perceptions from past experiences to learn that dairy/lactose-containing foods can be easily incorporated into the diet.

8. Consider the consumption of calcium-fortified foods.

The idea behind having more dairy is getting the calcium it provides. If you don't want dairy in your diet, calcium supplements are a useful source. Just be sure not to take more than 500 mg of calcium in any individual dose. Some people get constipation from calcium supplements. Before quitting them, try increasing the amount of fiber and water in your diet to see if that counteracts the constipation.

Children can take any of several varieties of supplements, including the common calcium carbonate (which is more likely to be found in chewable form), calcium citrate, and calcium glubionate.

Report From the LI Conference, part 23

The next presentation gives a useful follow-up to yesterday's post about the power of probiotics.

Treatment Recommendations in Adults With Diagnosed Lactose Intolerance
Jeanette N. Keith, M.D.
Associate Professor
Department of Nutrition Sciences
Department of Medicine
The University of Alabama at Birmingham

Probiotics can be helpful but people shouldn't expect to have them work instantly. In fact, any new dietary plan takes times to be effective.

In practice, we explain that just as it takes about 21 days to learn a new behavior, adaptation of the gut to a lactose-containing diet generally requires 3 weeks of consistent dietary change to achieve full tolerance.

As a nutritionist, rather than a research scientist, Dr. Keith had some crucial points that all practicing doctors should remember.

Patients like specifics rather than generalizations. That's the toughest thing for me to do, since I don't know you, don't know your medical history, don't know your symptoms, don't know all the little details that make up a life. Most of my advice here is generalized squared.

Doctors should do better, but too often they don't. A probiotic, for example, isn't a magic pill. Bacteria take time to multiply and drive out competing strains. If a doctor tells you to try them but nothing more, what do you do if you don't see improvement in three days? Or even a week? Many people would toss the probiotic and curse the doctor for making them spend unnecessary money. I'd much rather come out of a doctor's office knowing that I might have to wait for three possibly agonizing weeks for that wonderful symptom relief, even if I went in wanting that bit of magic.

Lactose intolerance is not a disease, despite what far too many people - and patients - think. The symptoms are all too real, though. Doctors need to understand what to ask about how people really eat, what tips to give, and how to steer individuals in the right direction.

The most effective dietary intervention for lactose intolerance is the one personalized to meet the needs of the individual affected by symptomatic lactose ingestion.

When you see your doctor, you need the best advice for you. Personally. I hope doctors are reading this.

Report From the LI Conference, part 22

First prebiotics and then, logically, probiotics. It's like scientists were methodical or something.

Strategies for Managing Individuals With Diagnosed Lactose Intolerance: Probiotics
Mary Ellen Sanders, Ph.D.
Consultant
Dairy and Food Culture Technologies
Executive Director
International Scientific Association for Probiotics and Prebiotics
Centennial, Colorado

As I also reported yesterday, probiotics are bacteria or other organisms that produce beneficial effects. More specifically, getting bacteria that can digest lactose (by making their own lactase) into the large intestine means that they can reduced or eliminate symptoms by digesting the lactose that reaches them before it can ferment and give off gas.

The evidence, as usual, is small and mixed. You need to read the presentation summary carefully to realize that what it means to you isn't the same as what it means to scientists. Researchers may get excited by knowing that certain bacteria give better results in breath hydrogen tests, because that may point the way to better delivery mechanisms or knowledge of when and how to take them.

What's of far more importance to you here and now is that any of the probiotics will give symptom relief. Streptococcus thermophilus (ST) and Lactobacillus bulgaricus (LB) are the types found in yogurt, but you have to ensure that you get yogurt with the National Yogurt Association LAC seal that indicates that "live and active" cultures will be in the finished product. Other types are used in probiotic capsules, including Bifidobacterium and Lactobacillus acidophilus. Those should work, but the evidence is sketchier.

Report From the LI Conference, part 21

We're in the final stretch of the conference, the Tuesday morning presentations, all of which were devoted to addressing the question "What Strategies Are Effective in Managing Individuals With Diagnosed Lactose Intolerance?"

To be honest, we didn't get much of an answer from the first presenter, although he covered some issues I wasn't familiar with, issues that touch on the answer tangentially.

Prebiotics and Lactose Intolerance
David S. Newburg, Ph.D.
Associate Professor of Pediatrics
Harvard Medical School
Director
Program in Glycobiology, Pediatric Gastroenterology and Nutrition
Massachusetts General Hospital

Prebiotics are any food component that promotes beneficial bacterial growth. I've covered them before, in Prebiotics and Probiotics, where I quoted a fuller definition:

Prebiotics ("before life") are nondigestible or fiber components of foods, usually complex carbohydrates that beneficially affect the host by stimulating the growth of intestinal bacteria. Certain bacteria prefer a particular prebiotic to use as a source of energy.

Lactose itself can be considered a prebiotic, because the changes in the bacteria that live in your colon from the types that ferment lactose and produce gas to the types that digest lactose and are symptom-free is certainly a beneficial change. If you read me regularly you know that the change usually requires both time and persistence. By having dairy in your diet regularly you can promote the beneficial bacteria. Or you can try taking probiotics - foods or medications that contain the good bacteria - and have them colonize your large intestine.

Why do you need to spend so much time on this? Dr. Newburg said that just introducing a new species of bacteria doesn't make a lasting change. Unless you keep reinforcing the switchover by constant application, your bacteria, known as your intestinal flora, go back to the way they were in a few days or weeks.

Report from the LI Conference, part 20: Question 3 Summary

The NIH LI Conference draft report summaries the presentations from Szilagyi and Savaiano and Levitt to answer question 3.

What amount of daily lactose intake is tolerable in subjects with diagnosed lactose intolerance?

Among individuals appropriately diagnosed with lactose intolerance, differences in a variety of factors—including lactase activity, gastric emptying rates, fecal bacterial metabolites, colonic mucosal absorptive capacity, and intestinal transit time—can greatly influence their susceptibility to develop intolerance symptoms following the ingestion of foods and beverages containing lactose. Individuals differ in the intensity of symptoms of lactose intolerance due to differences in abdominal pain perception and psychological impact of pain and social discomfort. Determining the amounts of lactose that can be tolerated is an important step in developing evidenced-based dietary recommendations that meet the needs of the individual.

High-quality evidence to address the question is limited as documented by the 28 studies summarized in the systematic evidence review. Studies were variable in terms of the definitions of lactose intolerance, study population selection criteria, how lactose was administered, and the type of assessment methods. The lack of validated measures made quantifying the severity of symptoms difficult to interpret. The majority of studies used a single dose of lactose without food and evaluated short-term responses. Efforts often were not made to mask the taste difference between lactose-free milk and milk containing lactose.

To assess tolerability, only a handful of studies tested the subjects in a double-blinded fashion with increasing amounts of lactose administered throughout the day to determine the daily tolerable load of lactose. Furthermore, the majority of studies examined small numbers of subjects, and no data were reported on the relationships of age, sex, or race/ethnicity. No studies focused exclusively on children; two studies examined adolescents exclusively; and two others included both children and adolescents. Only two studies were conducted on pregnant women; none focused on lactating women.

In the majority of available studies, subjects were classified as malabsorbers or absorbers based on breath hydrogen measurements or a blood glucose test, and symptoms of lactose intolerance were not always required for study entry. A blinded control was rarely employed to define lactose intolerance at study entry; thus it is probable that some individuals would have reported symptoms following ingestion of lactose-free solutions. The majority of studies investigated individuals with proven lactose malabsorption, not diagnosed lactose intolerance. As a result, only recommendations for individuals with proven lactose malabsorption and perceived lactose intolerance can be made with reasonable assurance.

The available evidence suggests that adults and adolescents who have been diagnosed with lactose malabsorption could ingest at least 12 grams of lactose when administered in a single dose (equivalent to the lactose content found in 1 cup of milk) with no or minor symptoms. Individuals with lactose malabsorption can tolerate larger amounts of lactose if ingested with meals and distributed throughout the day. However, 50 grams of lactose (equivalent to the lactose content found in 1 quart of milk) usually induces symptoms in those adults with lactose malabsorption when administered as a single dose without meals. For women with lactose malabsorption, tolerance to dietary lactose may improve during pregnancy but then worsen after delivery. Some data suggest that the routine ingestion of lactose increases the amount of lactose that is tolerable in both adults and adolescents. There is no scientific evidence to identify the tolerable dose of lactose for children with lactose malabsorption.

We stress the importance of additional scientific investigations to provide evidence-based and culturally sensitive recommendations about the amount of daily lactose intake that can be tolerated by lactose-intolerant individuals, with special emphasis on pediatric and adolescent populations and pregnant and lactating women.

Report from the LI Conference, part 19

This presentation and the next one are going to infuriate everyone. They're so connected that I'm going to vary from the way I've been handling these posts and put the two of them together.

Dosing, Symptoms, and Tolerable Doses of Lactose
Dennis A. Savaiano, Ph.D.
Professor and Dean
College of Consumer and Family Sciences
Department of Foods and Nutrition
Purdue University

Evidence-based Practice Center Presentation III: The Tolerable Amount of Lactose Intake in Subjects With Lactose Intolerance
Michael Levitt, M.D.
Professor
Minneapolis Veterans Affairs Medical Center
Division of Gastroenterology
Department of Medicine
University of Minnesota

The titles sound innocuous enough. If you click over and read the summaries of the presentations, you'll see that in broad generalities they say very little that I haven't said before and haven't repeated what feels like a dozen times just in my reports on the NIH Conference.

Believe me, the talks that they gave weren't so bland. I'll put it into a sentence.

Nobody gets symptoms from lactose.

Ridiculous, right? Ludicrous even. This whole blog is about lactose intolerance. My books are about LI. The conference was the state-of-the-science on LI. I've received thousand of letters and emails and posts from people telling me about their LI symptoms. Both presenters are researchers who've spent entire careers writing about LI.

Something's totally nuts here. I wish I knew what.

Figures 1 and 2 from Levitt's presentation won't reproduce well here so you have to click over and look at them. They represent the findings from a series of major studies on lactose. A minus sign means that a certain dose of lactose - with other foods in Figure 1, by itself in Figure 2 - produced "no or trivial symptoms" in the test subjects. "Severe symptoms" - the kind I think I get and the kind you tell me you get - are represented by a double plus sign. Remember that an eight-ounce glass of milk has about 12 grams of lactose in it.

When you look at the charts you'll see minus signs for all doses up to and including 12 grams. Virtually no one in the entire set of experiments got symptoms from the lactose in a glass of milk. If you used milk itself or some equivalent, a dose closer to what happens in the real world when you have dairy, no one, not a soul, got symptoms from two full glasses of milk.

Their breath hydrogen goes up, the certain signal that they are lactase maldigesters. But no symptoms.

Savaiano talked about experiments in which subjects received 50 grams of lactose over the course of a day without a single one of them having any symptoms.

Look, as I've reported earlier, the testing in the medical literature is bad. The groups are small, the experiments are not blinded, the doses are not physiologic, meaning that they don't correspond to the foods or eating experiences you get in everyday life. Still. Nothing? No symptoms? Sure, forcing a test subject to drink a full 50 grams of lactose in water - at one time the standard amount of lactose used in testing - will make people sick. But that's like testing for drunkenness by forcing a jug of moonshine down your craw in a single gulp. Anybody would be affected by that. It's so bad a test that doctors stopped recommending its use decades ago.

I didn't get it then, and I don't get it today. I'm reporting what the medical journal evidence says. In the next part I'll give the summary from the draft report. But I'll put the concluding paragraph here.

We stress the importance of additional scientific investigations to provide evidence-based and culturally sensitive recommendations about the amount of daily lactose intake that can be tolerated by lactose-intolerant individuals, with special emphasis on pediatric and adolescent populations and pregnant and lactating women.

That's the biggest "we don't understand what the hell's going on, give us some funding money" you'll ever see in scientific language.

Report from the LI Conference, part 18

Back at the NIH LI Conference, the presenters were ready to tackle question 3.

What Amount of Daily Lactose Intake Is Tolerable in Subjects With Diagnosed Lactose Intolerance?

Adaptation to Lactose Intolerance
Andrew Szilagyi, M.D., FACN, FRCPC
Assistant Professor of Medicine
McGill University School of Medicine
Department of Medicine
Division of Gastroenterology
The Sir Mortimer B. Davis Jewish General Hospital

Szilagyi is pronounced something like Siz-lah-ee.

What does it mean to be adapted to LI? It all relates to the big gap between people who have undergone testing to show that they don't digest lactose and the people who report symptoms of lactose intolerance. Some people who do digest lactose report symptoms in any case. But most people with lactase malabsorption - the technical term - aren't really all that bothered by milk.

I've covered some of these already, but we went over the list again. Having certain types of bacteria in the colon mean that less lactose is fermented and less gas created. Slowing the transit time through the intestines means that whatever small amounts of lactase remain have more chance to work on the lactose.

He also cited some studies that said that pregnant women have fewer symptoms, but worse symptoms after delivery. I've received email from women who are on both sides: some say their symptoms lessen, some say that pregnancy made it worse. But the evidence from these studies is interesting.


Improved lactose digestion during pregnancy: a case of physiologic adaptation?

Obstet Gynecol. 1988 May;71(5):697-700.
Villar J, Kestler E, Castillo P, Juarez A, Menendez R, Solomons NW.

Loss of intestinal lactase activity among adults could theoretically limit milk consumption and hence dietary availability of calcium during pregnancy. The present study sought to define, using breath hydrogen (H2) production as an index of incomplete carbohydrate absorption, the prevalence during pregnancy of lactose maldigestion of 360 mL of milk (18 g of lactose), and to determine whether lactose digestion improved as pregnancy advanced. The prevalence of lactose maldigestion among 114 pregnant women tested before the 15th week of gestation was 54%. By term, 44% of those originally classified as maldigesters had become digesters. There was a significant reduction in the four-hour sum of the changes in breath H2 concentration from the period before 15 weeks (116.6 +/- 9.6 ppm) to the time after 36 weeks (54.4 +/- 7.3 ppm; P less than .01). This apparent adaptive improvement in intestinal handling of milk lactose during gestation has implications for calcium intake and absorption.

Report from the LI Conference, part 17: Question 2 Summary

The Draft Report summarized the presentations that looked at Question 2 (Weaver; Heaney; and Wilt) as follows:

2. What are the health outcomes of dairy exclusion diets?

The health outcomes of dairy exclusion diets depend on whether other sources of nutrients, such as calcium and vitamin D, occur in the diet in sufficient quantities to replace dairy products as a source of these nutrients, and to what extent other components of milk are beneficial.

Calcium is necessary for normal growth and bone development as well as subsequent maintenance of bone density. The strongest argument for promotion of dairy ingestion is the beneficial effect of calcium (and fortified vitamin D in milk) on growth and development of the skeleton. Calcium is necessary for adequate bone accretion and optimal peak bone mass, which is a major determinant of risk for osteoporosis and fragility fractures later in adult life. Evidence suggests that certain age groups, such as children and teenagers, may be at increased risk for deficient bone acquisition if their diets are deficient in calcium or vitamin D. There is weak evidence that children with diets deficient in calcium have increased fracture rates. The maximal accumulation of bone mineral, and therefore the maximal calcium requirement, occurs during puberty. Although studies indicate that young children who drink milk are likely to meet or exceed the adequate intake for calcium, teenagers, as a group, tend not to take in enough calcium to meet recommended needs. This is exacerbated by dairy avoidance in individuals who consider themselves to be lactose intolerant, regardless of whether they have undergone objective testing for lactose intolerance.

Studies have demonstrated that the presence of lactose does not necessarily affect the efficiency of calcium absorption across the intestine, and that lactase nonpersisters do not have significant impairment in calcium absorption. Thus, the limiting factor in achieving optimal peak bone mass in young individuals is the intake of calcium. Similarly, in older individuals, low calcium intake rather than deficient absorption appears to be a major factor contributing to loss of bone mass. Replacement of calcium using supplements or dairy products slows the rate of bone loss in older people, possibly as a result of an overall decrease in bone turnover. Across the age spectrum, the factor limiting adequate calcium accrual in many individuals appears to be dairy avoidance.

Dairy exclusion diets may exacerbate the risk for osteoporosis for those already at greatest risk. These include women throughout the life cycle and certain racial/ethnic groups. Low intake of dairy products may place African Americans and others at risk for deficiencies of other necessary nutrients for bone health such as vitamin D, in addition to low calcium intake. Individuals with diseases that result in decreased calcium absorption due to intestinal inflammation (inflammatory bowel disease) or that require the use of corticosteroids (which in themselves directly reduce bone mass) have increased risk of osteoporosis.

Dairy exclusion diets may decrease gastrointestinal symptoms (bloating, cramps, flatus, and diarrhea) in symptomatic individuals who have lactose malabsorption or lactose intolerance. The degree of relief is likely related to the level of expression of lactase and the quantity of lactose ingested. People who remain symptomatic on a dairy exclusion diet may have other causes for their gastrointestinal symptoms, such as irritable bowel syndrome, celiac disease, inflammatory bowel disease, or small bowel bacterial overgrowth.

Dairy exclusion diets may affect other health outcomes. In several studies, individuals taking calcium supplements or increased dairy intake have decreased blood pressure. Calcium supplementation has been suggested to improve cardiac and vascular smooth muscle contractility; however, additional research is needed to clarify whether this has a significant impact on cardiovascular risk. Calcium ingestion has been associated with decreased risk of development of adenomatous colon polyps; it is not known whether this translates into decreased rates of colon cancer. One area of recent interest is the effect of lactose ingestion on colonic bacterial populations, as this may increase production of fatty acids such as butyrate, which may promote mucosal growth and reduce inflammation.

Report from the LI Conference, part 16

You want embarrassing?

Say you have a major federal agency, one that has responsibilities for a major, crucial, fraction of the nation's wellbeing. Call it, say, the National Institutes of Health. Make them responsible for the program of a major scientific get-together, say the state-of-the-science conference on Lactose Intolerance. And give that agency the very simple, basic responsibility of making the individual segments of that conference program accessible on the Internet, say, by posting links to each presentation and abstract. You do that, as everyone who has any knowledge of the Internet knows, by taking the URL and adding a # plus the name of an internal link.

So the URL for a link to, say, Evidence-based Practice Center Presentation II:
The Bone Health Outcomes of Dairy-Exclusion Diets by Timothy J. Wilt would read something like this:

http:// consensus.nih.gov/2010/lactoseabstracts.htm #Wilt

Simple enough.

Unless, that is, said Timothy J. Wilt, M.D., M.P.H. is the author of two different presentations. In which case, a URL that reads:

http:// consensus.nih.gov/2010/lactoseabstracts.htm #Wilt

takes you to the first of the two. And never the second. So I can't give you a direct link to the abstract of Evidence-based Practice Center Presentation II:
The Bone Health Outcomes of Dairy-Exclusion Diets because the boneheads at the NIH didn't think to make the link read #Wilt2.

Programming, even HTML-markup, is all details. Mistakes and typos are all too easy to make. But somebody has to click on all the links to make sure they work!

Anyway, for all the info about Dr. Wilt and his co-authors, see the entry I posted about part I of their multi-part presentation.

This particular presentation looked again at actual consumption of nutrients among those who had dairy and those who didn't. What happens with those who don't eat or drink dairy? They don't get enough calcium.

Vegan children consumed only 47% of the RDA for calcium. Vegan women got even less, a mere 30%.

The numbers were extremely similar for LI children (45%) and LI women (37%). LI, lactose intolerance, is being defined here as anyone who claimed symptoms from dairy. Those who tested as having a lactase deficiency, technically a somewhat different group, had a somewhat but not terribly different pattern, 44% for children, 50% for women. (Why no results for men? Apparently none of the 52 studies they summarized looked specifically at males apart from other groups.)

Does this lack of calcium make any real different for bones? The evidence there was thoroughly mixed. Some studies found no differences at all, but many did show increases for bone problems of all sorts for people who avoided dairy.

Report from the LI Conference, part 15

Scientists are nothing is not methodical. After examining the consequences of dairy avoidance in children, you couldn't have found a sports book in all Las Vegas that would be willing to take money against what the next panel would be.

Consequences of Excluding Dairy or of Avoiding Milk in Adults
Robert P. Heaney, M.D., FACP, FACN
John A. Creighton University Professor
Osteoporosis Research Center
Professor of Medicine
School of Medicine
Creighton University

To no one's surprise, Dr. Heaney found that adults who think they have lactose intolerance tend to avoid dairy. And in fact, studies have found anywhere from 33% to 80% lower calcium intake in lactose intolerant populations.

Part of his talk did differ from expectations. In what should also be to no one's surprise, taking a properly close look at the nuances give a picture of reality at odds with conventional wisdom.

But it is an oversimplification to focus exclusively on single nutrients, even calcium. Nutrients are not drugs, and they do not act in a vacuum. Rather, like the instruments in a symphony orchestra, they produce their effects in concert with one another. A striking example of this mutual dependence is seen in the interaction of calcium and protein in the diet. Until recently, high protein intakes were considered to be potentially harmful for bone because of their effect on urinary calcium excretion. Increased calciuria was clearly demonstrated for protein and for pure amino acids, whether taken orally or intravenously. However, when protein was fed as a food, strangely there was no effect on calcium balance. More recently, it has become clear that calcium and protein, rather than antagonists, are actually synergistic in their skeletal effects. In postmenopausal women with low protein intakes, increasing calcium intake can slow bone loss, but not much more. By contrast, with high protein intakes, added calcium leads to actual bone gain. This is an important consideration in our context because individuals with low dairy intakes are missing not only the calcium but also a rich source of dietary protein, which is as necessary for bone rebuilding as is the calcium that is the more obvious component of bony material.

In brief, dairy supplies a broad spectrum of nutrients that work together better than gaining them individually or from foods less gifted. Even calcium-fortified orange juice isn't anywhere as good a source as dairy.

And here's a tidbit that will infuriate those who cherry-pick the medical journals for anti-milk reports.

While the focus of this session is predominantly on skeletal effects, it should be stressed that inadequate dairy intake has multiple other consequences as well, including increased risk of metabolic syndrome, hypertension, preeclampsia, obesity, and certain forms of cancer, particularly colon cancer. Thus milk avoidance is, for most adults, a risky behavior.

Reality is a harsh mistress.

Report from the LI Conference, part 14

For the next three posts, we'll be in Section 2 of NIH state-of-the-state presentations on Lactose Intolerance.

What are the health outcomes of dairy exclusion diets?

Consequences of Excluding Dairy, Milk Avoiders, Calcium Requirements in Children
Connie M. Weaver, Ph.D.
Distinct Professor and Head
College of Consumer and Family Sciences
Department of Foods and Nutrition
Purdue University

Although it is perfectly true that a totally adequate intake of nutrients can be achieved without consuming any dairy products, the reality is that Americans as a whole don't follow anything like that diet. They don't come close to getting sufficient nutrients even with dairy. The numbers are scary.

The role of milk products in meeting three nutrients for various age groups is illustrated in Table 1.

Most food guidance patterns recommend 3 cups of low-fat dairy products daily. The table contrasts the proportion of individuals meeting the dairy recommendations with those receiving less than one serving of dairy products as assessed from data from the 1999–2004 National Health and Nutrition Examination Survey (NHANES). The best and most economical source of the limiting nutrients is dairy. Supplements typically do not fill the gap of all these nutrients for those who do not consume recommended intakes of dairy products. Using NHANES 2001–2002 data, Gao et al. determined that it is impossible to meet calcium recommendations while meeting other nutrient recommendations with a dairy-free diet within the current U.S. dietary pattern. Using the 1999–2004 NHANES data, Nicklas et al. determined that < 3% of the U.S. population met potassium recommendations and 55% did not even meet their Estimated Average Requirements for magnesium.

Bone mass growth comes during adolescence, with 95% of adult peak occurring by age 16. Getting proper nutrients in childhood in critical. Dairy drinkers have a real advantage in driving those numbers up to and past the critical requirements. Here's a table of what the bone-related nutrient requirements are for those under 18.

Report from the LI Conference, part 13a: Question 1 Summary

The Draft Report summarized the presentations that looked at Question 1 (Tishkoff; Wooten; Wood; and Wilt) as follows:

1. What Is the Prevalence of Lactose Intolerance, and How Does This Prevalence Differ by Race, Ethnicity, and Age?

The prevalence of lactose intolerance is difficult to discern because studies have varied in their interpretation of what constitutes this condition. To estimate accurately the prevalence of lactose intolerance, one first must define lactose intolerance to permit the identification of those individuals with the condition and the exclusion of those without the condition. By applying this definition to a representative population sample, one can then estimate the prevalence in the general population and assess how this prevalence differs by age and race/ethnicity. We define lactose intolerance as the onset of gastrointestinal symptoms following a blinded, single-dose challenge of ingested lactose by an individual with lactose malabsorption, which are not observed when the person ingests an indistinguishable placebo. Although lactose malabsorption and lactase nonpersistence can be easily identified, they are not equivalent to lactose intolerance.


The prevalence of lactose intolerance in the United States cannot be estimated, despite a systematic evidence review that identified 54 articles, including 15 studies in the United States with a total of 4,817 participants. None of the studies used this definition or evaluated a representative sample of the U.S. population. Seven studies that assessed self-reported lactose intolerance provide limited insight because the self-diagnoses were not confirmed by testing for lactose malabsorption, and the symptoms seen in true lactose intolerance may result from several other conditions such as irritable bowel syndrome. Nine studies evaluated only the genetic predisposition to lower than expected levels of lactase in adults (lactase nonpersistence) without assessing lactose malabsorption or intolerance directly. Five studies reported decreased intestinal tissue lactase activity, and 31 studies addressed lactose malabsorption directly (as evidenced by a positive hydrogen breath test after ingestion of lactose).


Although these studies shed some light on the epidemiology of lactose intolerance (discussed below), they cannot be used to estimate the prevalence of lactose intolerance. Many individuals who have the biologic underpinnings for lactose malabsorption (low lactase levels or a genetic profile associated with low lactase) or who have demonstrated lactose malabsorption do not experience the onset of or an increase in the severity of gastrointestinal symptoms following a blinded lactose challenge. Complicating this further, evidence demonstrates that many who self report lactose intolerance show no evidence of lactose malabsorption. Thus, the cause of their gastrointestinal symptoms is unlikely to be related to lactose.


Despite the limitations in the available studies discussed above, several trends are noteworthy across the studies regarding lactose intolerance, lactose malabsorption, lactase nonpersistence, age, and race/ethnicity. First, lactose intolerance determined by self-report or nonblinded lactose challenge is less frequent across all ethnic groups than is lactose malabsorption determined by breath hydrogen tests or lactase nonpersistence determined by biopsy or genetic testing. Second, lactose intolerance, lactose malabsorption, and lactase nonpersistence vary across racial and ethnic groups with the lowest reported occurrence in European Americans and higher although variable occurrence in African Americans, Hispanic Americans, Asian Americans, and Native Americans. The systematic evidence review notes that the racial and ethnic variability in lactose intolerance following nonblinded lactose challenge was not as extreme as that reported in lactose malabsorption and lactase nonpersistence. Third, lactose intolerance with nonblinded lactose challenge and lactose malabsorption was low in young children, but increased with age. In children younger than 6 years, lactose malabsorption was low in all the studies and peaked between ages 10 and 16 years. Little evidence suggests that lactose intolerance increases in older persons. These trends need to be verified by representative population studies using the case definition of lactose intolerance

Report from the LI Conference, part 13

Take a deep breath. You're about to be socked with the longest title and longest list of authors of the whole conference.

Evidence-based Practice Center (EPC) Presentation I: Methods of Systematic Review and the Prevalence of Lactose Intolerance and Differences by Race, Ethnicity, and Age
Timothy J. Wilt, M.D., M.P.H.
Codirector, Minnesota Evidence-based Practice Center
Core Investigator, Minneapolis Veterans Affairs Center for Chronic Disease Outcomes Research
Professor of Medicine
University of Minnesota School of Medicine

Want the full list of co-authors? Here. Timothy J. Wilt, M.D., M.P.H.; Aasma Shaukat, M.D., M.P.H.; Tatyana Shamliyan, M.D., M.S.; Brent C. Taylor, Ph.D., M.P.H.; Roderick MacDonald, M.S.; James Tacklind; Indulis Rutks; Sarah Jane Schwarzenberg, M.D.; Robert L. Kane, M.D.; Michael Levitt, M.D.

They didn't all get up on stage at once, or the auditorium would have become unbalanced and slid into the Potomac. In preparation for the conference, a team of experts combed through all the literature, hundreds, maybe thousands, of studies, to collect every one that looked at various populations. They then did a review of all the applicable studies to see what conclusions could be drawn from everything that had been written on the subject.

Some people say that only double-blinded studies (studies in which neither the testers nor the testees known what exactly what is in the test products) are suitable for drawing serious scientific conclusions. All right, me. I've said it.

Here's the problem. There aren't any. None.

Okay, so this isn't a cancer drug that will decide life or death. Maybe we can go with blinded studies, i.e., those in which just the test subject doesn't know whether there's lactose in the drink or not.

None.

What? That can't possibly be? Nobody has ever bothered to blind-test lactose versus a placebo? The Coke/Pepsi challenge was more rigorous than that.

But the disheartening results give the bad news in so many words.

A total of 54 articles met inclusion criteria, including 15 articles from the United States. Studies did not directly assess LI in a blinded lactose challenge but instead assessed unblinded subjective LI symptoms, an inability to fully absorb lactose (LM), or lactase nonpersistence. The data available tended to be from highly selected populations and were likely not representative of the overall U.S. population. We report results according to the following conditions: LI, LM, or lactase nonpersistence. Within these conditions, we further describe findings according to assessment method and populations studied.

Man, that's ugly.

The truth is that scientists got all hot and bothered about LI when they first started looking around the world and finding it everywhere. Most of those studies took place back in the 1970s. Once they found that lactose malabsorption was common and traced the route that lactase persistence took that made most people in northern Europe milk drinkers, they stopped caring. LI isn't really a medical problem, so the medical community has never been terribly interested in studying all the effects. We just don't get sick enough to make us worth their attention.

Is that good news or bad news?

Report from the LI Conference, part 12

Back from a short lunch we plunged directly into more presentations.

Aging: Lactose Intolerance and Calcium Absorption in the Elderly
Richard J. Wood, Ph.D.
Associate Professor
Department of Nutrition
School of Public Health & Health Sciences
University of Massachusetts

We're a nation of just over 300,000,000 people. We're also an aging nation. People are living longer than ever before, and the demographic bulge caused by the vastly increased birthrates that represent the baby boomer generation is moving to the older segment of the population. The first boomers are turning 64 this year. By the year 2030 there will be an estimated increase of 33 million people in the 65 and over age bracket, making a total of 25% of Americans. You can't blame the boomers entirely. The oldest will be only 84 that year but a full 5% of the population will be 85 or over then.

What happens to humans as they become older, an older population than ever before? Specifically, what do we know about the elderly and LI? As will be a woefully recurring theme, the answer is "next to nothing."

Although many studies have characterized the prevalence of lactose maldigestion and symptoms of lactose intolerance in various adult populations, there is surprisingly little information concerning this condition in the elderly, especially in the very old (>80 years). What little evidence is available indicates that the prevalence of lactose maldigestion may increase with age in adults, but that symptoms of lactose intolerance do not increase with age.

Little evidence means little evidence. Apparently fewer than a hundred elderly in total have ever been investigated in LI studies.

And those meager results are big time compared to the number of elderly patients tested to see whether lactose malabsorption affects calcium absorption. We just don't know. The possible good news is that tests on younger patients don't show any difference. Keep on having calcium in whatever form you like.

Report from the LI Conference, part 11 [Lunch]

Bethesda, MD, was still recovering from the giant snowstorms of the previous weeks, with sidestreets lined with cars that nobody had bothered digging out from the packed snow thrown up by the plows. That Monday of the conference was chill and rainy and thoroughly miserable (as I found later that day, when I missed a shuttle bus back to my hotel by moments and waited 25 minutes for the next one to arrive, having only a sport coat to break the cold). The good news is that the NI thoughtfully held the conference in a building containing a major cafeteria. The bad news - or at least the comical news - occurred just as the entire conference descended on the cafeteria only to find that the last tray had been scarfed by the NIH's normal inhabitants. The distinguished group balancing plates, soup bowls, bottles, and silverware on top of briefcases, purses, and coats looked more like extras from a Laurel and Hardy movie.

I managed to snag the last seat at a crowded table of the large Lactaid contingent plus Alan Kligerman. We had a mutual admirefest (I have fans, who knew?) and the conversation was lively, if heavy on shoptalk.

Since none of the questions I asked in any of the discussion periods had been answered (nobody has any idea of the duration, rate, or variation of the time it takes to lose lactase production, e.g.) I thought I'd try a more practical question given the expertise I had on hand.

I've been asked multiple times why no lactose-free powdered milk is available to consumers. Alan said that it simply doesn't work. When lactose-free milk is dried, the result is brown, smelly, and bad-tasting.

What likes heat? Chocolate. All the Lactaid people agreed that the chocolate milk Alan had created was one of their best-tasting products, because chocolate loves heat.

So next time you each for a lactose-free carton of milk, try the chocolate. It has approval from on high.