Correspondence
Lactose Intolerance
N Engl J Med 1995; 333:1358-1359November 16, 1995
- Article
To the Editor:
Suarez et al. (July 6 issue)1 found that “people who identify themselves as severely lactose-intolerant may mistakenly attribute a variety of abdominal symptoms to lactose intolerance.” The lack of information about their subjects' symptoms after ingesting 15 g of lactose makes it impossible to determine whether any of those studied were truly lactose-intolerant — that is, whether or not they experienced gastrointestinal symptoms in addition to malabsorbing lactose. Subjects who were asymptomatic after consuming the test dose of lactose would not be expected to report any differences in symptoms between milk and lactose-hydrolyzed milk.
1 ReferencesMarvin S. Medow, Ph.D.
Howard R. Sloan, M.D., Ph.D.
New York Medical College, Valhalla, NY 105951
Suarez FL ,Savaiano DA ,Levitt MD . A comparison of symptoms after the consumption of milk or lactose-hydrolyzed milk by people with self-reported severe lactose intolerance. N Engl J Med 1995;333:1-4
Full Text | Web of Science | Medline
To the Editor:
Presumably, millions of people with low levels of intestinal lactase are clearly symptomatic after drinking a glass or two of skim milk on an empty stomach. Whole milk, with its fat content, leaves the stomach more slowly than skim milk. Since the threshold for symptoms is doubled when milk or lactose is taken with a meal,1 the investigators should have tested people who became clearly symptomatic with a glass of milk taken with a standardized meal and then conducted a double-blind challenge with milk and lactose-hydrolyzed milk. There were so few symptoms with their study regimen of milk with the subjects' usual breakfasts that any effects of lactose and lactose hydrolysis were not noticeable. The breakfasts could have contained various amounts of fat, which delays gastric emptying and thereby limits the flow of lactose into the intestine, the site of the lactase enzyme.
1 ReferencesTheodore M. Bayless, M.D.
David M. Paige, M.D., M.P.H.
Marshall S. Bedine, M.D.
Johns Hopkins Hospital, Baltimore, MD 21287To the Editor:
The addition of aspartame to increase the sweetness of the nonhydrolyzed milk is a matter of concern. I have encountered nausea, bloating, abdominal pain, flatus, and diarrhea (at times bloody) in scores of people with unequivocal reactions to products containing aspartame.1,2 These features were reproducible on rechallenge in the majority. Such intolerance often complicated the diagnosis among patients with various gastrointestinal disorders, including lactose intolerance and diabetic neuropathy.2
2 ReferencesH.J. Roberts, M.D.
Palm Beach Institute for Medical Research, West Palm Beach, FL 33407To the Editor:
Allergy to milk was not mentioned as a cause of milk intolerance. Patients with milk allergy may tolerate milk protein and lactose after their allergies subside.
David L. Morris, M.D.
Allergy Associates of La Crosse, La Crosse, WI 54602-2408To the Editor:
The study by Suarez et al. was well designed and well reported. Unfortunately, the families in my practice are more apt to read the capsule summary that Dr. Levitt, one of the authors, gave to the media: “The final result is, there is virtually nobody out there who cannot tolerate a glass of milk a day.”1 Neither this statement nor the Associated Press article in which it was included makes it clear that the conclusions apply only to the group of adults who were studied. Lactose intolerance is a condition that generally begins in childhood, and it is not unreasonable to suspect that a child will be affected by a much smaller volume of milk than an adult more than twice his or her size. In addition, that child is much more likely to be served a full eight fluid ounces of milk in a carton at school or day care, not to mention milk on cereal for breakfast, a glass of milk at supper, and the occasional ice cream for dessert.
As a pediatrician, I work hard to persuade some of the parents in my practice that their children need less milk, not contrast studies or endoscopy. Dr. Levitt may well have erased all of my effort with one ill-considered sound bite.
1 ReferencesDiane Lind Fenster, M.D.
1625 Patton St., Green Bay, WI 54301Author/Editor Response
The authors reply:
To the Editor: Our goal was to carry out a double-blind, randomized investigation of the symptomatic responses to the daily ingestion of a cup of milk by subjects self-identified as being severely lactose-intolerant. Medow and Sloan suggest that only those who had symptoms after the initial testing with 15 g of lactose should have been included in the double-blind study. The sole purpose of the initial testing with 15 g of lactose was to determine the frequency of lactose malabsorption in this self-diagnosed group of subjects. Since this lactose load was provided in nonblinded fashion, analysis of associated symptoms would have provided little useful information.
We agree with Bayless et al. that symptoms resulting from lactose malabsorption may be influenced by foods eaten in conjunction with lactose. We evaluated the symptomatic response to milk drunk in the usual fashion with a meal. The results suggest that a cup of milk drunk with breakfast resulted in negligible symptoms in a group of subjects who had previously believed that ingesting this quantity of milk would result in severe symptoms.
As indicated by Morris, symptoms following the ingestion of milk could be the result of allergy to milk proteins or lactose intolerance. In adults, milk allergy is thought to be very rare relative to the high frequency of lactose malabsorption. Although our trial was designed to study symptoms resulting from lactose ingestion, the absence of appreciable symptoms with either conventional or lactose-hydrolyzed milk suggests that we were not dealing with milk allergy masquerading as lactose intolerance.
We agree with Fenster that our findings in adults cannot necessarily be extrapolated to children. Symptoms of lactose intolerance are more likely to occur as the dose of lactose is increased. Given the lower weight of children, they could experience symptoms after drinking an amount of milk that is tolerated by adults. In discussions with the media, we consistently attempted to limit our conclusions precisely to who and what were studied — that is, adults ingesting a cup of milk daily with breakfast.
Roberts suggests that our results could have been confounded by symptoms resulting from the aspartame used to sweeten the conventional milk. We specifically excluded subjects who had known problems with aspartame. More important, symptoms resulting from aspartame should have enhanced the response to the conventional milk containing lactose, thus artifactually increasing rather than obscuring lactose-induced symptoms. Our finding of similar symptoms with conventional and lactose-hydrolyzed milk suggests that neither lactose nor aspartame caused appreciable symptoms.
Fabrizis L. Suarez, M.D.
Dennis A. Savaiano, Ph.D.
University of Minnesota, St. Paul, St. Paul, MN 55455Michael D. Levitt, M.D.
Veterans Affairs Medical Center, Minneapolis, MN 55417- Citing Articles (1)
Citing Articles
1
Veronica Ojetti, Rossella Mura, Maria Assunta Zocco, Paola Cesaro, Ercole Masi, Antonietta La Mazza, Giovanni Cammarota, Giovanni Gasbarrini, Antonio Gasbarrini. (2008) Quick Test: A New Test for the Diagnosis of Duodenal Hypolactasia. Digestive Diseases and Sciences 53:6, 1589-1592
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