Lactose malabsorptionfrom yogurt, pasteurized yogurt, sweet acidophilusmilk, and cultured milk in lactase-deficientindividuals15

Lactose malabsorption from yog u rt, pasteurized yogurt, sweet acidophilus milk, and cultured milk in lactase-deficient individuals15 Dennis

A Savaiano,

Michael

D Levitt,

P/iD,

Abdeihak

AbouElAnouar,

DAG,

David

E Smith,

PhD,

and

MD

KEY WORDS baci//us acidophi/us,

Lactose cultured

malabsorption, milk

Infroduction The use of yogurt, cultured milk, and other fermented dairy products is common in areas ofthe world where lactase deficiency is prevalent (1). We have recently demonstrated that subjects who are lactase deficient more effectively digest and absorb lactose ingested in yogurt as compared to lactose in milk (2). This enhanced digestion of lactose in yogurt is apparently a result of the inherent 8-galactosidase activity in yogurt. We have measured sufficient B-galactosidase activity in the duodenum of lactase-deficient subjects after yogurt ingestion to account for the enhanced lactose digestion (2). The microorganisms used to ferment or enrich dairy products other than yogurt also contain a B-galactosidase or phospho-B-galactosidase (3). Therefore, it is possible that other fermented or microbial containing The American .Journa/ ofC’/inical Nutrition 40: DECEMBER 1984 American Society for Clinical Nutrition

©

lactase-deficiency,

breath

hydrogen,

yogurt,

Lacto-

dairy products in addition to yogurt may also selectively autodigest lactose. Herein we evaluate the digestion and absorption of lactose from three of these products: pasteurI

From

the Departments

ofFood

Science

and

Nutri-

tion and Medicine, University of Minnesota and the Research Service, Veterans Administration Medical Center, St Paul and Minneapolis, MN. 2 Supported in part by the University of Minnesota Agricultural Experiment Station, the Veterans Administration, the National Institutes of Health (5 RO1 AM 1 3309- 1 5), Marschall Products, Miles Lab Inc, Madison, WI and the North Carolina State University Dairy Foundation. 3 University of Minnesota Agricultural Experiment Station, journal article no 13,925. 4 Presented in part at the 44th Annual Meeting of the Institute of Food Technologist held in Anaheim, CAJune 10-13, 1984. 5 Address reprint requests to: Dennis A Savaiano, PhD, Department of Food Science and Nutrition, University of Minnesota, St Paul, MN 55108. Received April 30, 1984. Accepted for publication July 17, 1984. 1984,

pp 12 19-1223.

Printed

in USA

1219

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ABSTRACT The use offermented dairy foods is common in areas ofthe world where lactase deficiency is prevalent. Recently, we have shown that the digestion of lactose from yogurt is enhanced as compared to that from milk. This enhanced digestion is apparently due to inherent B-galactosidase in yogurt which is active in the gastrointestinal tract after consumption of the yogurt. Furthermore, yogurt is well tolerated by lactase-deficient subjects resulting in little or no gastrointestinal distress. Since other fermented and microbial-containing dairy foods are consumed worldwide and may also contain some “lactase” activity, we chose to evaluate the digestion oflactose from three ofthese products: pasteurized yogurt, cultured milk (buttermilk), and sweet acidophilus milk. Breath hydrogen techniques were used to evaluate lactose malabsorption in nine lactase-deficient subjects. The studies demonstrated that yogurt is unique among the products tested in enhancing the digestion of lactose. Furthermore, pasteurization of yogurt eliminated the enhanced digestion of lactose, reduced the inherent lactase activity of the yogurt by 10-fold and reduced cell counts by 100-fold. Interestingly, eight of nine subjects fed cultured milk experienced gastrointestinal distress, whereas all subjects fed pasteurized yogurt were symptom free, even though the amount of malabsorbed lactose was similar. Am J C/in Nutr 1984:40: 12 19-1223.

1220

SAVAIANO

ized yogurt, cultured milk (buttermilk), and sweet acidophilus milk, as well as from yogurt and milk. Our studies demonstrate that yogurt is unique among the products tested in enhancing the digestion of lactose in lactase-deficient subjects. Furthermore, pasteurization of yogurt eliminates the enhanced digestion of lactose presumably due to the reduction in the B-galactosidase activity in yogurt. Methods

ET

AL

All dairy products were formulated and processed in our dairy pilot plant from a single source of milk (University of Minnesota dairy herd). Fresh milk was pasteurized at 82#{176}C for 30 mm and homogenized at 2500 psi of pressure. A portion of the homogenized, pasteurized milk was inoculated with LBST yogurt starter culture (Marschall Products, Madison, WI) after Results the addition of 2% (by weight) nonfat dry milk. The inoculated, enriched milk was incubated at 37C until Figure 1 shows the mean breath hydrogen the pH reached 4.6 (approximately 1 1 h) and quickly cooled to 10 to l6C. The final pH ofthe yogurt ranged curves for the nine subjects for each of the from 4.3 to 4.5. One half of the batch of yogurt was five ingested dairy products. Peak changes pasteurized at 6YC for 30 mm. Another portion of the in breath hydrogen occurred 3 to 6 h posthomogenized, pasteurized milk was cooled to 22#{176}C, ingestion and ranged from a high of4O ppm inoculated with FRI buttermilk/sour cream starter culture (Marschall Products, Madison, WI) and incubated for milk and sweet acidophilus milk to a low until the pH reached 4.8 (approximately 16 h). The of 14 ppm for yogurt. All breath hydrogen cultured milk was quickly cooled to 10 to 16#{176}C. A final values were falling to near fasting levels at portion of the homogenized, pasteurized milk was the end of the 8-h collection period. cooled to 7#{176}C and inoculated with Lactohaccillus aciThe breath hydrogen values from 1 to 8 h dophilus, NCFM strain (GP Gunlock Co. Cincinnati, OH). All products were stored at 4#{176}C. The lactose postingestion were summed for each mdicontent of each was measured using a commercial vidual subject in order to estimate the total technique (Boehringer-Mannheim Biochemicals, Indihydrogen excretion resulting from the dairy anapolis, IN). All products were ingested within 10 days product meals (Fig 2). One-third to one-fifth oftheir formulation. The lactose content ofthe products was also measured at the end of 10 days and had not less hydrogen resulted from yogurt feeding changed. than from the other test meals. This differThe study group consisted of nine healthy subjects ence is significant at the p < 0.05 level when (20 to 28 yr of age) who were identified as lactase comparing acidophilus milk, milk, and culdeficient on the basis of a rise in breath hydrogen tured milk with yogurt and nearly significant concentration to over 20 parts per million (ppm) after ingestion of milk containing 20 g oflactose. End-alveowhen comparing pasteurized yogurt with yolar breath samples were obtained in the fasting state gurt (p < 0.08) using the Bonferroni method and hourly for 8 h after ingestion of the following test for correcting p values when performing meals: 410 g of milk, 420 g of sweet acidophilus milk, multiple paired I tests (4). Peak breath hy465 g of cultured milk (buttermilk), 500 g of yogurt, drogen excretion correlated well with the and 500 g of pasteurized yogurt. Each test meal contamed 20 g oflactose. Subjects were randomly fed each area under the breath hydrogen curve (r = of the coded meals on a blind basis (the subjects were 0.99, Fig 2) and was inversely correlated with not informed of the identity of each product but no the time since ingestion (r = 0.81). attempt was made to mask the flavor or texture). All Table 1 shows the percentage lactose, cell subjects gave informed consent and the project was approved by the Committee on the Use of Human counts, and lactase activity of each product. Subjects in Research of the University of Minnesota. The lactose content of the products were End-alveolar breath samples were obtained by haysimilar to other reported values (1, 5-i). ing the subject expire end-alveolar air into syringes Pasteurization of the yogurt reduced cell fitted with stopcocks. The samples were analyzed for hydrogen concentration with a Microlyzer model I2 counts by approximately 100-fold and lac-

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hydrogen gas analyzer (Quintron Instruments, Milwaukee, WI). The percentage ofcarbon dioxide in each gas sample was determined using a Beckman Medical Gas Analyzer (model LB-Il, Beckman Instruments, Fullerton, CA). The observed hydrogen values were then corrected for atmospheric contamination ofthe alveolar air by normalization to 5.0% carbon dioxide. The Iactase activity in each product was assayed by measurement of the initial rate of galactose appearance (Boehringer-Mannheim Biochemicals) in sonicated products at 37#{176}C (2). The number of viable microorganisms (presumably lactic acid starter bacteria) were measured by plate counts ofsweet acidophilus milk, cultured milk, yogurt, and pasteurized yogurt. The dairy products were mdividually blended at low speed to insure homogeneity and plated on MRS agar adjusted to pH 6.24 using 10fold serial dilutions ofthe products prepared with sterile saline. Plates were incubated anaerobically, using BBL Gas Packs, for either 48 h at 32#{176}C (cultured milk) or 72 h at 37#{176}C (yogurts and sweet acidophilus milk).

LACTOSE

MALABSORPTION

P.Yogurt

FIG 1. Change milk, and cultured deficient subjects.

1

2

in breath hydrogen milk. Each meal

3

4

TIME

(hours)

5

Cult.Milk

6

7

(ppm) after ingestion of yogurt, pasteurized contained 20 g of lactose. Results are the

__ r77zz C2

Milk

A.Milk

wm

i

1221

YOGURT

8 yogurt, sweet acidophilus mean ± SEM for nine

milk, lactase-

_

UP,n

250

200 150 100 50 U

U

111

YOGURT FIG 2. Summation ofthe breath pasteurized yogurt, sweet acidophilus deficient subjects. TABLE 1 Percentage lactose, cell counts, and dairy products fed to lactase-deficient Dairy

*

product

Yogurt Pasteurized yogurt Cultured milk Sweet acidophilus milk Milk (pasteurized) Galactose appearance at I h.

P.YOGURT

A MILK

MILK

CULT.MILK

hydrogen produced over the 8-h study period (ppm/h) milk, milk, and cultured milk. Results are means

lactase activity subjects

±

from SEM

meals of yogurt, for nine lactase-

in the five %

No cells/g

Lactaae

lactose

product

(mg/h/g

4.0 4.0 4.3 4.8 4.9

3.0 x l0 3.4 x l0 2.8 x l0 1.1 x l0 Not measured

activity#{176} product)

0.64 0.07 0.02 0 0

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0

FROM

1222

SAVAIANO

TABLE 2 No of subject s re porting meals (n = 9) .

Milk

Diarrhea Excessive

flatulence Abdominal pain No

Sweet

sympto acidophilus . milk

ms af ter dairy

Yogurt

Pasteurized

yogurt

product Cultured . milk

1 3

3 4

0 0

0 0

2 8

1

0

0

0

4

4

5

9

9

1

symp-

toms

Discussion The results confirm that unpasteurized yogurt enhances the digestion of lactose in lactase-deficient subjects. This effect is due to the inherent lactase activity in yogurt (Table 1) which, as we have shown previously, survives gastric digestion and is active in the duodenum during the consumption of yogurt (2). However, pasteurization of yogurt destroys most of the lactase activity (Table 1). As a result, lactose malabsorption is increased when pasteurized rather than unpasteurized yogurt is fed. Feeding sweet acidophilus milk or cultured milk as compared to milk did not significantly alter the extent of digestion of lactose in lactase-deficient subjects. It is interesting that although pasteurization increased lactose malabsorption from yogurt, the nine lactase-deficient subjects uniformly reported no gastrointestinal (GI) distress symptoms after consuming pasteurized yogurt. In contrast, the consumption of

AL

cultured milk resulted in almost uniform GI distress despite a similar extent of lactose malabsorption. This apparent contradiction indicates that other factors in addition to lactose digestion are involved in creating or preventing GI distress during the consumption of dairy products by lactase-deficient subjects. Such factors might include the physical state of the products, the products’ effect on stomach emptying, organic compounds produced by the dairy microbes which may interact in the intestine, and the composition of the gases produced during fermentation. The anaerobic fermentation of carbohydrate results in the production of carbon dioxide, methane, and hydrogen. The ratio ofgases produced is dependent on a complex mixture of factors including microorganisms and substrates present, temperature, reaction time, and pH. While hydrogen and methane are relatively water insoluble (50 ml/ 100 ml water at 37#{176}C) and hence more rapidly cleared. It is possible that symptoms are due to the rate at which total gas is produced compared to the rate of clearance via the circulation and lungs. Differences in the mix ofgas produced (eg, more methane, less hydrogen) with different milk products could explain the disparity between perceived symptoms and breath hydrogen concentrations. However, it should be stressed that the flavor and texture of the various meals were not modified. It is also possible that these sensory attributes somehow influenced the reporting of the symptoms, all of which were subjective. It would be of interest to study symptoms after gastric administration of the test meals. Improved lactose digestion from sweet acidophilus milk has been both reported (8) and refuted (9, 10). However, earlier studies either failed to characterize the product under study (10), were long-term feeding studies that reported GI distress but no estimate of lactose malabsorption (9) or collected breath hydrogen samples only for 3 or 4 h (8) (an insufficient period to assess either the duration or extent of malabsorption). Our results clearly demonstrate that lactose from sweet acidophilus milk is not better absorbed than lactose from milk. Furthermore, both

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tase activity by approximately 10-fold. Only yogurt contained appreciable lactase activity. However, trace amounts oflactase activity were found in the cultured milk and pasteurized yogurt. The sweet acidophilus milk contained approximately l0 cells per g but no measurable lactase activity. The number of subjects reporting gastrointestinal symptoms including diarrhea, excessive flatulence, and pain are shown in Table 2. No symptoms were reported when yogurt or pasteurized yogurt were fed, whereas eight of the nine subjects reported symptoms when cultured milk was fed. Four and five of the nine subjects, respectively, reported symptoms when milk and sweet acidophilus milk were fed.

ET

LACTOSE

MALABSORPTION

3.

4. 5. 6.

7.

8.

9.

References 10. 1. Tamine AY, Deeth HC. Yogurt: technology biochemistry. J Food Prot 1980:43:12,939-77. 2. Kolars JC, Levitt MD, Aouji M, Savaiano

and DA.

YOGURT

I223

Yogurt: an autodigesting source of lactose. N Engi J Med 1984:310:1-3. McKay LL. Regulation of lactose metabolism in dairy streptococci. In: Davies R, ed. Developments in food microbiology. Vol 1. Essex, England: Applied Science Pub Ltd. 1982. Miller RG. Simultaneous statistical inference. New York, NY: Springer-Verlag Inc. 1981. Deeth HC, Tamine AY. Yogurt: nutritive and therapeutic aspects. J Food Prot 198 1 ;44:78-86. Gilliland SE, Kim HS. Influence ofyogurt containing live starter culture on lactose utilization in humans. An Sci Res Rep OkIa Agric Exp St l983;xx:l 13-16. Alm Ll. Effect offermentation on lactose, glucose, and galactose content in milk and suitability of fermented milk products for lactose intolerant individuals. J Dairy Sci 1982;65:346-52. Gilliland SE, Kim HS. Influence of Lactobacillus acidophilusadded to milk on lactose malabsorption in humans. An Sci Res Rep OkIa Exp St 198 1;xx:263-9. Newcomer AD, Park HS, O’Brien PC, McGill DB. Response ofpatients with irritable bowel syndrome and lactase deficiency using unfermented acidophilus milk. Am J Clin Nutr l983;38:257-63. Payne DL, Welsh JD, Manion CV, Tsegaye A, Herd LD. Effectiveness of milk products in dietary management of lactose malabsorption. Am J Clin Nutr 198l;34:27l 1-15.

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sweet acidophilus milk and milk caused GI distress in approximately one-half of the subjects under study. Cultured milk is typically fermented with Streptococcus lactis or Streptococcus cremoris and Slactis sub sp diacetylactis. These microbes have a phospho-B-galactosidase which can only use phosphorylated lactose as a substrate (3). This phosphorylation requires a functional permeability system (intact cell membrane) (3). Our results suggest that either there is insufficient phospho-Bgalactosidase activity in cultured milk to significantly enhance lactose digestion or more likely, the cell membrane phosphorylation system is disrupted during digestion. Disruption of cell membranes by sonication resulted in trace lactase activity in cultured milk (Table 1). U

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