Bovine Milk Protein-Induced Intestinal Malabsorption of Lactose and Fat in Infants

Vol. 54, No.1 Printed in U.S.A.

GASTROENTEROLOGY

Copyright

© 1967 by The Williams

& Wilkins Co.

BOVINE ~IILK PROTEIN-INDUCED INTESTINAL MALABSORPTION OF LACTOSE AND FAT IN INFANTS HSI-YEN LIU,

M.D., M. U.

TSAO,

PH.D., B.

MOOHE,

B.A.,

AND

Z.

GIDAY

Department of Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan

set varying from birth to 6 weeks of age. Familial tendency was present in each case: at least one parent plus a sibling had similar histories of milk-induced bloating, diarrhea, and weight loss. Oral lactose tolerance curves obtained on admission were all flat by our standards (fig. 1). Dietary exclusion of cow's rriilk was followed in all by dramatic symptoma tic relief. One to 7 months following milk withdrawal, when the patients were asymptomatic, in robust health, and gaining weight steadily, each was admitted to the University of Michigan Clinical Research Unit and fed our "base line formula" 16 (table 1). This was designed to approximate cow's milk in caloric content as well as fat, protein, and carbohydrate composition. But, more importantly, (1) it provided a nonbovine source of protein; (2) its carbohydrate was solely dextrose; and (3) the formula was so constructed that lactose could be substituted for dextrose, gram for gram, at will. The carbohydrate content of this formula lies between that of human and cow's milk, being 6.3%. Initially, all infants were fed the dextrose-containing base line formula ad libitum, supplemented with calcium (dicalcium phosphate, 0.5 g, b.i.d.) and water-miscible multivitamins in standard doses (Zymadrops, 0.6 cc, q.d.). Oral lactose tolerance curves and 72-hr fecal fat determinations were obtained during three parallel test periods: (1) when the patients were fed the dextrose-containing base line formula; (2) when they were fed the lactosecontaining base line formula; and (3) when they were fed cow's milk proteins in one of two ways: (a) as whole cow's milk (WCM) , replacing the base line formula feedings; or (b) as added doses of bovine proteins while the patients were fed the dextrose-containing base line formula. The protein additives consisted of the following, one at a time: bovine serum albumin, bovine serum globulin, ,8-lactoglobulin (,8-LG), a-lactalbumin, (Nutritional Biochemical Corporation, Cleveland, Ohio) or

Since the original descriptions by Durand 1 and Holzel et a1. 2 of infants with intestinal malabsorption of lactose, the pathogenetic role of the unhydrolyzed, unabsorbed disaccharide in producing osmotic diarrhea has come to be widely3-S accepted. The therapeutic efficacy of dietary exclusion of lactose-containing foods has led some 9 to postulate a specific deleterious effect of lactose upon the intestinal mucosa, resulting in malabsorption not only of lactose, but, often, also of fat. 3, 4, 10-15 The present study was designed to determine in 4 such infants (1) whether or not oral lactose per se was capable of producing intestinal malabsorption of lactose and fat, and if not (2) whether fed bovine milk proteins could.

Methods The clinical material included 4 full term infants, 1 ~egro and 3 Caucasians, 1 boy and 3 girls, ages 6, 212, 3, and 9 months respectively, who presented with vomiting, massive acid diarrhea, marked electrolyte and water depletion, and failure to gain weight while drinking cow's milk formulae, with onReceived May 1, 1967. Accepted September 8,1967. Address requests for reprints to: Dr. Hsi-Yen Liu, Department of Pediatrics, University of Michigan Medical Center, Kresge 2, R6036, Ann Arbor, Michigan 48104. A preliminary report of the data contained herein was presented at the annual meeting of the Midwest Society for Pediatric Research, Chicago, Illinois, November 1, 1966. This investigation was supported in part by ResearCH Grant AM-08494 from the National Institutes of Health, H. H. Rackham Research Grant 604, and Public Health Service Research Grant 5 MOI-FR-42-04 from the Division of Research Facilities and Resources. 27

28

Vol. 54, No.1

LIU ET AL. TABLE

1. Base line formula

1. Content

Lamb a Corn oilb Carbohydrate-dextrose' or lactose d Water 2. Calories 19.6 cal per oz of formula 41% from fat 39% from carbohydrate 20% from protein 3. Carbohydrate composition Dextrose or lactose = 6.3% (Lactose composition of WCM = 4.8%) Gerber's strained lamb. lVlazola corn oi!. 'uSP 10% D-glucose for intravenous use (Baxter Laboratory, :Viorton Grove, II!.). d USP !'i-lactose, reagent grade (Nutritional Biochemical Corporation, Cleveland, Ohio). a

c

Pet skim milk powder, each in quantities contained in 100 to 200 ml of skim milk.'7 Consecutive feeding test periods were separated by intervals of 1 week to 3 months. All tests were performed when the patients were free of medication, fever, infection, or gastrointestinal symptoms. Oral lactose tolerance tests were done with 10% f3-lactose loads of 2 g per kg of body wt, following a 6- to 8-hr fast. Venous samples were obtained before and after the loading at 3D-min intervals for 2Y2 hr, during which the patients were recumbent and asleep without sedation.' • All bloods were immediately pipetted, placed on ice, deproteinated, and analyzed in duplicate for glucose and total reducing substances, using the glucose oxidase's (Worthington Biochemical Corporation, Freehold, New Jersey) and Nelson Somogyi' • methods respectively. Consecutive tests were performed at intervals of at least 3 days. Fat balance was conducted with quantitative analyses of all intake and stools during the balance period marked by carmine red. Daily fat intake varied between 36 and 64.4 g with a single exception of 29 g in 1 infant at 4 months of age. Daily carbohydrate intake varied between 45 and 104.63 g. Fecal fat analyses were carried out in triplicate using the method of van de Kamer.'" Stool weights were measured before and after oven evaporation. "Wet weight" refers to weight before drying. Stool pH was determined by means of a pH meter (Beckman Zeromatic). All fecal

analyses were done in the Clinical Research Unit Laboratory under the direction of Dr. Joseph P. Chandler. All food quantitations were made in the Clinical Research Unit Metabolic Kitchen.

Results

Oral lactose tolerance tests (fig· 1). While the patients were drinking cow's milk formulae on admission, maximal rise of their plasma glucose from fasting to peak after lactose loading ranged from 15 to 35 mg per 100 ml. During remission, 2 to 7 months following cow's milk withdrawal, while they were drinking dextrose-containing base line formula, the maximal rise of plasma glucose ranged between 60 and 96 mg per 100 ml and, while they were drinking lactose-containing base line formula, the maximal rise of plasma glucose for each was in the same range as that found with dextrose formula feeding. When milk proteins were fed prior to the tolerance tests in the following manners: (1) WCM-as regular feedings for 7 days before the test in case 1, (2) skim milk powder in a single lO-g dose orally, 6 hr prior to the tolerance test in cases 2 and 3, and (3) skim milk powder in daily 20-g doses added to dextrose-containing base line formula feedings for 8 days before the tolerance test in case 4, the post-lactose loading maximal plasma glucose rise fell to levels of 26 to 51 mg per 100 ml, representing a statistically significant (see legend of fig. 1) drop in each case (P < 0.01). Fecal water loss (table 2). During remission, 2 to 7 months following cow's milk withdrawal, while fed either dextroseor lactose-containing base line formula, wet wt of stools ranged between 31 and 63.3 g per 24 hr, with no statistical difference between dextrose or lactose feedings. Stool pHs were all >7.0. During the milk protein feeding period (as WCM or lactose-containing base line formula plus f3-LG) , there was a 2- to 4-fold increase in the daily wet wt of stools with pH ranging from 4.5 to 6.0. Daily carbohydrate intake in each case (table 2) clearly did not account for the observed change in fecal

January 1968

29

INTESTINAL MALABSORPTION IN INFANTS

ORAL LACTOSE TOLERANCE 100 90

Control Ronge = 60 -104

80

~it 0:0 70 ., E en0...,

<.> 0 .=!., 60

C>(l.

E~ 50

en co

E

<:

(l. ..,

en

0&

.~ o

40

D Case _ I -6mos. .I 2 - 2'i\! mo. f I§I Cose _ 3 - 3mos. f • Cose _ 4- 9 mos. f

rm Cose _

E 30

0

~.t

20 10 0

EM SKI t.! WCM WCt.!

SKIM MILK MILK MLIK

L

WC ~ S KI~ SKI ~

M2

D or L

FIG. 1. Maximal plasma glucose rise following oral lactose loading: M,-during initial diagnosis, while being fed bovine milk (EM, evaporated milk; SKIM, skim milk; and WCM, whole cow's milk). D or L-during remission following milk withdrawal, while being fed dextrose (D) or lactose (L) containing base line formula. Results during D or L feedings were not significantly different. Only L-associated values are represented. M,,-during bovine milk proteins refeeding. The differences between Land 1112 values were significant (P < 0.01) in each case. Controls-values (glucose oxidase method) were obtained in 24 separate oral lactose tolerance tests on 16 subjects with no clinical or laboratory sign of lactose malabsorption or diabetes mellitus. One of the subjects was an adult. The infants and children were 2 months to 14\12 years of age. Data from 9 additional unaffected pediatric subjects whose maximal plasma sugar rise exceeded 60 mg per 100 ml are not included because only the Nelson-Somogyi method was used. Statistics-standard error of our true glucose determinations, based on 965 paired analyses, was ±3.74%. The smallest difference 60 - 44 16, or a decrease observed between Land jlf 2 values was in case 4, where d of 26.7%; t > 7; P < 0.01.

=

water, which was responsible for twothirds of the increase in wet wt. Fecal fat loss (fig. 2). During remission, 2 to 7 months following cow's milk withdrawal, while the patients were fed the dextrose-containing formula, the percentage of ingested fat in their stools ranged between 0.68 and 1.7% and, while they were fed the lactose-containing formula, this figure ranged from 0.766 to 2.2%. However, when they were fed cow's milk protein in the form of WCM feedings, or ,B-LG (0.244 g daily added to dextrosecontaining formula feedings), the percent-

=

age of ingested fat in their stools rose to the range of 10.75 to 22.75%.

Serial determinations following milk protein withdrawal and refeeding (fig. 3).

Following strict dietary exclusion of cow's milk, while they were fed the dextrosecontaining base line formula, the 2 younger patients (2Y2 and 3 months in age) showed steadily progressive decrease in fecal fat along with progressive increase in their maximal plasma glucose rise following lactose loading. It was not until 2 to 3 months later before these values finally reached the normal range, concurring with

30

LlU ET AL. TABLE

2. Average daily stool wet weight a Diet

Case

Md

LC

Db

IIl-LG6+ L

WCM g/24 hr

1 2 3 4

31' (74.44)U 62 (90) 32 (60) 49.3 (104.63)

32.3 (lO4.38) 63.3 ~lOO . 31) 44 (45)

lO6.7 (88 .32) 125 (77 .34)

146 (72 . 19) 142.3 (92.62)

Wet wt = wt before oven drying. D, dextrose-containing base line formula feeding. c L, lactose-containing base line formula feeding. d M, cow's milk proteins feeding. 60.244 g daily, added to L. f Numbers outside parentheses represent wet wt of stool. g Numbers in parentheses represent dextrose or lactose ingested. a b

clinical tolerance of ingested lactose. On the other hand, the 2 older patients, first seen at 6 and 9 months respectively, took 7 to 14 months of cow's milk exclusion before their lactose tolerance maximal rise gradually returned to normal. By thi s time, neither had chemical steatorrhea or clinical intolerance of lactose feeding. When the fecal water, pH, fat, and maximal plasma glucose rise following lactose loading reached normal values and stabilized in each patient, determined by repeated measurements, lactose was substituted for dextrose in the base line formula. Essentially the same normal results found with dextrose feeding were duplicated. In the 2 younger patients, initial trial challenges using various individual milk proteins revealed quite different individual reactions to BSA, producing steatorrhea and "flattening" of the oral lactose tolerance curve in only 1 (case 2) of the 2 babies. But both of them showed marked reaction to ,B-LG,and still more to skim milk powder. Therefore, in the 2 older pa-

FECAL FAT

25

20

Vul. 54, No.1

C=:J

Cose * I - 6mos. , Cose *2 - 2'hmo. ~ ~ Cose *3 - 3 mos. ~ ~

E

~

15

IlIlIlIIIIIlII Cose

*4

- 9mos. ~

'0

.,co

~

II>

E

10

o

WC,", p-lG p-lG WC,", D

L

M

FIG. 2. Fecal fat during the feeding of dextrose-containing base line formula (D); lactose-containing base line formula (L); and bovine milk proteins (M) in the form of whole cow's milk (WGM) or ,B-lactoglobulin (,B-LG), 0.244 g daily, added to D. Difference between Land M values was significant (P < 0.01), but difference between D and L values was not.

INTESTINAL MALABSORPTION IN INFANTS

FECAL FAT

24

Case "" 1- 6 mos. d' Case "" 2- 2 V2 mOs. ? 3- 3 mos. ~ Case Case # 4- 9 mos. ~

20

'u;8

0--0

"*'

16

.!:

~

...

12

'"

8

.!:

)«

4

WCM

WCM

~

~

31

M I

I

I

0

0

.-.. '" .,.

I

I

I

I

I

I

.0

.I

f

./

.I

0

L. '

0---"-'"

i

./

_ 100

.. )«

Control range • 60 -104

D::E 80 ~

0 ...

U o

.E! ..

(!)D..

60

00

EI-

..

",

.!'!c

D&

40

0.;

E 'iCE

00

~~

~

LACTOSE TOLERANCE

20 0

I

0

2

I

4

I

I

6

I

I

8

I

I

10

I

I

12

1I

14

I

16

Intervol From Lost Milk -Ingestion (month)

FIG. 3. Serial fecal fat and oral lactose tolerance test results following (1) bovine milk withdrawal (M), (2) substitution of lactose (L) for dextrose (D) in the base line formula, and (3) subsequent refeeding of bovine milk proteins. All values between M and L were those obtained during the feeding of D-containing base line formula. In the lower graph, D and L values were statistically the same and not separately indicated. Following milk withdrawal, fecal fat progressively decreased as postlactose load plasma glucose maximal rise gradually increased, but both promptly reversed upon refeeding of certain bovine milk proteins. (See text for keys to all symbols.) While case 2 reacted to BSA feeding, case 3 did not.

tients, who came later, only mixed milk proteins contained in skim milk powder or in the form of WCM were used for challenges. Statistically significant steatorrhea and flattening of the oral lactose tolerance curve promptly resulted in all (P < 0.01), accompanied by the reappearance of acid, watery stools. Clinical response. During remission following cow's mjlk withdrawal, all 4 babies had sanguine disposition; excellent appetite; zero to three small, formed, alkaline stools daily; freedom from gastrointestinal symptoms and signs; enhanced energy in motor and social responses; and sustained, normal to accelerated rate of weight and height increments. Ingestion of lac-

tose without bovine milk proteins produced loose, acid stools and bloating only during the early phase of recovery, but no symptom or sign once remission was established. The feeding of milk proteins without lactose, on the other hand, led to development of inconsolable crankiness; anorexia; episodic vomiting; colicky abdominal cramps; mild abdominal distention; some flatulence; frequent, bulky, foul, mucus-laden, loose to mushy, alkaline to acid stools; marked lassitude and sleepiness; occasional prostration; and cessation of weight gain or rapid weight loss. When bovine milk proteins were fed with lactose, there was more obvious increase in abdominal distention and pains;

32

LIU ET AL.

Vol. 54, No.1

ing mucosa,9 or an osmotic induction of hyperperistalsis. 3, 7, 12, 14 This concept of the pathogenetic mechanism necessitates xx an existing defect in the hydrolysis and absorption of lactose, attributable, in most x cases, to intestinal lactase deficiency. Disf3 Z quieting, however, are the accumulating '" fX data 23 -25 showing lack of consistent cor~ '"w g relation between intestinal lactase activity ~ and clinical milk intolerance. In the pres~ 0 m ent series, 3 of the 4 babies also had flat oral glucose-galactose tolerance curves (11 to 43 44 '=O--=A":::GE:-:(""'mo-n"'-th'"")-~28 mg per 100 ml maximal rise of plasma glucose) on admission, accompanied by acid • ADMISSIQN (Before Fl ) diarrhea after loading; all showed normal X LATEST (After ~) gluco~e tolerance curves during remission; AGE (month) 28 and, III the 3 infants tested, milk protein FIG. 4. Body length and weight before (.) feedings led to 26.4 to 65.6% depression of and after (X) milk withdrawal (ll). Based on the maximal plasma glucose rise following percentile chart of infant physical measurements oral glucose loads, down to the abnormal constructed by Harold C. Stuart, Department of range (31 mg per 100 ml) in one. That Maternal and Child Health, Harvard School of ~onosaccharide absorption can be similarly, Public Health. Values for the single male infant were adapted to conform in percentile values for If to a less extent, affected by milk protein feeding provides for the possibility of paboys. tients having milk-induced signs of carboflatulence; water content, volume, acidity, hydrate malabsorption without biochemiand explosiveness of stools; and systemic cal evidence of lactase deficiency, casting further doubts upon the exclusive claim of signs of water and electrolyte deficit. Height and weight gain (jig. 4). Before this disaccharidase lack as the prime bovine milk withdrawal, only 1 of the 4 in- cause of milk intolerance. Indeed, Lubos fants studied showed marked statural et al,24 have seriously questioned the role stunting (below the 3rd percentile for the of milk sugar in the production of milk-inappropriate age and sex), while all 4 suf- duced gastrointestinal symptomatology. fered distinct failure to gain weight Kern et aJ.12 and Burke et aJ.15 did con(around the 3rd percentile). Following sider the etiological· role of milk proteins bovine milk withdrawal, at their latest in the genesis of lactose and fat malabsorpmeasurements, both the heights and the tion, only to reject the notion after experiweights of all 4 babies were found be- mental data seemingly excluded the possibility. Kern et aJ.12 produced, in an adult tween the 25th and the 75th percentile. following small bowel resection, more steatorrhea while feeding her lactose than Discussion when she was fed casein and lactalbumin. In the past year, the subject of intestinal The apparent relative innocuousness of malabsorption of disaccharides has been these two milk proteins in this case may 5 extensively reviewed. , 7, 8, 21, 22 The assohave been a function of the patient's speciation of lactose malabsorption with steatorrhea in milk-intolerant patients has cific insensitivity to them,26, 27 a dose-rebeen noted by a number of authors.3, 4, 10-15 sponse phenomenon, or the inability of cerTo date, the most prevalent explanation tain variables to alter detectably a gross for the widespread malabsorption of nu- malabsorption secondary to massive loss of trients in these cases incriminates the un- absorbing surface. Burke et al.,15 in their absorbed lactose as the agent producing report of 13 infants with lactose malabeither. a "toxic" effect upon the absorb- sorption, cited 4 patients in whom the 100

LU ~

LENGTH

January 1968

INTESTINAL MALABSORPTION IN INFANTS

pathogenetic significance of cow's milk proteins was discredited on the basis of unconvincing results from intradermal and serum precipitin tests against milk antigens. In view of the work of Heiner,28 Gerrard et al.,29 Goldman et al.,so and Lubos et al.,24 one might question the expectation of necessarily finding antibodies against food antigens in skin-fixed or circulating sites. Hence, the failure to demonstrate circulating antibodies or reagins against milk antigens need not exclude their role in the production of gastrointestinal pathology. In fact, there is ample documentation of the role of bovine milk proteins in the pathogenesis of steatorrhea. 31 - 34 To our knowledge, the present study is the first to demonstrate the adverse effect of ingested milk proteins on the absorption not only of fat but also of lactose in certain susceptible patients. Furthermore, it seems to point to milk proteins and not sugar as the pathogenetic constituent of cow's milk when the latter produces intestinal malabsorption in "sensitive" subjects. Of particular interest is the capability of such ubiquitous dietary proteins as bovine milk proteins and gliadin, even in small quantities, to alter a major physiological function within hours of ingestion in certain apparently healthy subjects. This raises a question as to the definition of socalled "control values" in intact biological systems, where the limits of potential variables controlling such values have yet to be defined. The exact mechanism by which bovine proteins induce intestinal malabsorption cannot be deduced from data presented in this study. Its elucidation promises to be exciting. Summary

A nonbovine, dextrose-containing formula was fed to 4 babies with lactose malabsorption in remission. Substitution of lactose for dextrose in the formula did not produce steatorrhea, flattening of the oral lactose tolerance curves, or acid, watery stools, but the prior feeding of selected bovine milk proteins, skim milk, or whole

33

cow's milk did. Thus, it would seem that in certain human subjects, at least, it is the proteins, and not the carbohydrate, in cow's milk that can precipitate intestinal mala bsorption. REFERENCES 1. Durand, P. 1958. Lattosuria idiopatica in una

paziente con diarrea cronica ed acidosi. Minerva Pediat. 10: 706-711. 2. Holzel, A., V. Schwarz, and K. W. Sutcliffe. 1959. Defective lactose absorption causing malnutrition in infancy. Lancet 1: 1126-1128. 3. Weijers, H. A., J. H. van de Kamer, W. K. Dicke, and J. Ijsseling. 1961. Diarrhoea caused by deficiency of sugar splitting enzymes. I. Acta Paediat. (Stockholm) 50: 55-71. 4. Sunshine, P., and N. Kretchmer. 1964. Studies

of small intestine during development. III. Infantile diarrhea associated with intolerance to disaccharides. Pediatrics 34: 38-50. 5. Prader, A., and S. Auricchio. 1965. Defects of intestinal disaccharide absorption. Ann. Rev. Med. 16: 345-358. 6. Crane, R. K. 1966. Enzymes and malabsorption: a concept of brush border membrane disease. Gastroenterology 50: 254-262. 7. Townley, R. R. W. 1966. Disaccharidase deficiency in infancy and childhood. Pediatrics 38: 127-141. 8. Cornblath, M., and R. Schwartz. 1966. Dis-

9. 10.

11.

12.

13.

14. 15.

orders of carbohydrate metabolism in infancy, p. 258. W. B. Saunders Company, Philadelphia. Holzel, A., T. Mereu, and M. L. Thomson. 1962. Severe lactose intolerance in infancy. Lancet 2: 1346-i348. Thornton, A. A., J. H. Burkinshaw, and E. Kawerau. 1962. Chronic diarrhea relieved by lactose-free diet. Proc. Roy. Soc. Med. 55: 979-981. Cozzetto, F. J. 1963. Intestinal lactase deficiency in a patient with cystic fibrosis. Pediatrics 32: 228-233. Kern, F., Jr., J. E. Struthers, Jr., and W. L. Attwood. 1963. Lactose intolerance as a cause of steatorrhea in an adult. Gastroenterology 45: 477-487. Lifshitz, F., and G. H. Holman. 1964. Disaccharidase deficiencies with steatorrhea. J. Pediat. 64: 34-44. Lifshitz, F. 1966. Congenital lactase deficiency. J. Pediat. 69: 229-237. Burke, V., K. R. Kerry, and C. M. Anderson. 1965. The relationship of dietary lactose to

34

16. 17. IS.

19. 20.

21.

22.

23.

24.

25.

LIU ET AL. refractory diarrhoea in infancy. Aust. Paediat. J. 1: 147-160. Liu, H. Y., and M. U. Tsao. A case of intestinal and renal malabsorption of monosaccharides. Amer. J. Dis. Child. In press. Cole, W. Q., and S. C. Dees. 1963. Allergenic properties of milk and milk proteins. J. Pediat. 63: 256-263. Keston, A. S. 1956. Specific colorimetric enzymatic reagents for glucose, p. 31c. In Abstracts, 129th Meeting of the American Chemical Society. Nelson, N. 1944. A photometric adaptation of the Somogyi method for the determination of glucose. J. BioI. Chem. 153: 375-380. van de Kamer, J. H. 1953. Quantitative determination of the saturated and unsaturated higher fatty acids in fecal fat. Scand. J. Clin. Lab. Invest. 5: 30-36. Haemmerli, U. P., H. Kistler, R. Ammann, T. Marthaler, G. Semenza, S. Auricchio, and A. Prader. 1965. Acquired milk intolerance in the adult caused by lactose malabsorption due to a selective deficiency of intestinal lactase activity. Amer. J. Med. 38: 7-30. Littman, A., and J. B. Hammond. 1965. Diarrhea in adults caused by deficiency in intestinal disaccharidases. Gastroenterology 48: 237-249. Dunphy, J. V., A. Littman, J. B. Hammond, G. Forstner, A. Dahlqvist, R. K. Crane. 1965. Intestinal lactase deficit in adults. Gastroenterology 49: 12-21. Lubos, M. C., J. W. Gerrard, and D. J. Buchan. 1967. Disaccharidase activities in milk-sensitive and celiac patients. J. Pediat. 70: 325-331. Newcomer, A. D., and D. B. McGill. 1966. Lactose tolerance test in adults with nor-

26.

27.

2S.

29.

30.

31. 32.

33.

34.

Vol. 54, No.1

mal lactase activity. Gastroenterology 50: 340-346. Goldman, A. S., D. W. Anderson, Jr., W. A. Sellers, S. Saperstein, W. T. Kniker, and S. R. Halpern. 1963. Milk allergy. 1. Oral challenge with milk and isolated milk proteins in allergic children. Pediatrics 32: 425-443. Heiner, D. C. 1963. Comments, p. 130. In S. S. Gellis [ed.], Year book of pediatrics, 19631964 series. Year Book Publishers, Inc., Chicago. Heiner, D. C. 1963. Comments, p. 133. In S. S. Gellis [ed.], Year book of pediatrics. 1963-1964 series. Year Book Publishers, Inc., Chicago. Gerrard, J. \V., D. C. Heiner, E. J. Ives, and L. W. Hardy. 1963. Milk allergy: recognition, natural history, and managemem. Clin. Pediat. (Philadelphia) 2: 634-641. Goldman, A. S., W. A. Sellers, S. R. Halpern, D. W. Anderson, Jr., T. E. Furlow, and C. H. Johnson, Jr. 1963. Milk allergy. II. Skin testing of allergic and normal children with purified milk proteins. Pediatrics 32: 572-579. Davidson, M. 1955. The celiac syndrome Pediatrics 21: 50S-511. Lamy, M., J. Frezal, and J. Rey. 1963. Le-; steatorrhees par troubles de l'absorptioll intestinale, p. 74. In Reports of the 2!l1 L Meeting of L'Association de Pedia!res d( Langue Francaise, Vol. 1. FKlstrom, S. P., J. Winberg, and H. J. Andersen. 1965. Cow's milk induced mabbwrption as a precursor of gluten intolerance. Acta Paediat. Scand. 54: 101-115. Davidson, M., R. C. Burstine, M. M. Kugler, and C. H. Bauer. 1965. Malabsorption defect induced by ingestion of beta lactoglobulin. J. Pediat. 66: 545-554.