Lactose tolerance in a jewish population

In order to investigate the possible effect of environment on lactose deficiency, lactose tolerance tests were performed on 32 healthy Jewish adults living in Western Canada. The results were compared with those obtained in Jewish communities in Israel. There were 20 males and 12 females, 20–47 years of age, with a mean of 27.2 years. The tests revealed that 22 (68.8%) of the subjects were lactose intolerant on the basis of a maximal blood glucose rise of less than 20 mg/100 ml above the fasting level after the lactose load. The mean maximum blood glucose rise was 4.1 mg/100 ml in the 22 lactose-intolerant subjects and 33.6 mg/100 ml in the 10 lactose-tolerant subjects. Gastrointestinal symptoms during the test were observed in 95.5% of the subjects with a low rise in blood glucose, and in 10% of those with a normal rise in blood glucose. There was no relationship between lactose tolerance and milk intake. The results suggest a high incidence of lactose intolerance among North American Jews, and are similar to findings in Jewish communities in Israel.Supported by Grant A6249, National Research Council of Canada.The author wishes to thank Dr. M. Lee for his helpful comments; and Dr. J. A. Birkbeck and Mrs. Karen M. Ulveteg for their assistance with the lactose tolerance test.     

Lactase deficiency in Singapore-born and Canadian-born Chinese

Seventy-three of 77 adult Singapore-born Chinese (95%) and 48 of 49 Canadian-born adult Chinese (98%) were demonstrated to be lactase deficient using the lactose breath hydrogen test. The similar prevalence of lactase deficiency in the Singapore- and the Canadian-born Chinese despite a larger estimated amount of daily milk ingestion in the Canadian-born Chinese (430 ml vs 157 ml) supports the concept that lactase deficiency, which is transmitted genetically, does not have an adaptable component related to the quantity of lactose ingested. When the lactose breath hydrogen test performed with a dose of 0.5 g/kg of lactose was compared with the test using a standard dose of 50 g of lactose, there was very little loss of sensitivity. In spite of the presence of lactase deficiency, only 32% of the Singapore subjects and 23% of the Canadian subjects had gastrointestinal symptoms when milk was ingested in the daily diet. Peak breath H₂ was higher in females than males, but the difference was more significant in the Canadian cohort.     

Double blind study of milk lactose intolerance.

One hundred and fifty subjects were studied in a double blind fashion to determine the relationship between lactose malabsorption and milk lactose intolerance. Each participant received 250 ml of a different type of milk on 3 consecutive days. Milk A contained no lactose, milk B had 12.5 g, and milk C contained 37.5 g of lactose. After the experiment was completed each subject was classified with a lactose tolerance test as having "sufficient" or "insufficient" lactase activity. Milk A produced no gastrointestinal symptoms in either sufficient or in insufficient persons. Milk B produced symptoms in 3.8% of sufficient and 37.1% of insufficient individuals, and Milk C induced symptoms in 7.6% of sufficient and 83.5% of insufficient subjects. These differences are very highly significant (P less than 0.0001). It is concluded that lactose-intolerant subjects are indeed milk-intolerant and that the frequency with which symptoms occur in persons with lactose malabsorption increases in direct relation to the lactose content of the milk.     

Use of the lactose-ethanol tolerance test in diabetes.

The standard lactose tolerance test involves measuring a patient's blood glucose after the ingestion of lactose. If the patient has lactase deficiency and is unable to hydrolyze lactose and absorb its monosaccharides, glucose and galactose, the blood glucose does not usually increase greater than 20 mg/100 ml. Since factors other than the absorption of glucose can cause an increase in the blood glucose of greater than 20 mg/100 ml in a diabetic, this test could be unreliable when it is performed on a diabetic. The present study was performed to determine whether the lactose-ethanol tolerance test could be used to diagnose lactoase deficiency in diabetics. This test involves measuring the blood galactase level, instead of the blood glucose, and the administration of ethyl alcohol to a subject prior to the test to delay the clearance of galactose from the circulation. The results indicate that the standard lactose tolerance test in which the blood glucose is measured is unreliable when performed on insulin-dependent diabetics, but that it can be reliable when performed on non-insulin-dependent diabetics. The lactose-ethanol tolerance test gave results in each type of diabetic which were qualitatively similar to those of nondiabetics. It was concluded that the latter test is a useful screening test for lactase deficiency in diabetics.     

Lactose tolerance in a Slavic population

In order to gather data on the frequency of primary lactase deficiency in various population groups, lactose tolerance tests were performed on 38 healthy adults of Slavic origin who had recently left Eastern Europe and are presently living in Western Canada. Twenty-one of the subjects were born in Poland and 17 in Czechoslovakia. There were 16 males and 22 females, aged 17–65 years, with a mean of 29.8 years. The tests revealed that 9 (23.9%) of the 38 subjects were lactose intolerant on the basis of both criteria, showing a maximum rise in blood glucose of less than 20 mg/100 ml above the fasting blood glucose level after ingesting 50 g of lactose, and experiencing gastrointestinal symptoms during the test. The mean maximum rise in blood glucose was 39.1 mg/100 ml in the 29 lactose tolerant subjects and 7.3 mg/100 ml in the 9 lactose intolerant subjects. Gastrointestinal symptoms during the test were observed in all 9 subjects with a low rise in blood glucose, and no symptoms were produced in any of the 29 subjects with a significant rise in blood glucose (> 20 mg/100 ml). Most of the subjects consumed 1 cup of milk per day. In addition, they were irregularly consuming lactose-containing products such as ice cream, chocolate drinks, etc. The results suggest a relatively low frequency of lactose intolerance among Eastern Europeans of Slavic origin, and in this respect, they resemble Northern Europeans.Supported by grants from the National Research Council of Canada (A6249), and from the Committee on Research of The University of British Columbia (26–9682).The author wishes to thank Dr. J. A. Birkbeck for his assistance.     

A New Type of Low-Lactose Milk

By ultrafiltration of skim milk a new low-lactose milk powder was developed whose lactose content was reduced by 86%. The lactose was replaced by malto-dextrin. In contrast to lactose-hydrolyzed milk powder, no protein-destroying processes (Mail-lard reactions) could be demonstrated during production or after storage at standard conditions. Tolerance of the new low-lactose milk versus regular skim milk was tested in 35 well-nourished, adult Latin Americans with lactose malabsorption. The ingestion of 500 ml of the low-lactose milk gave rise to significantly (p < 0.05) fewer symptoms than regular skim milk. After the intake of 250 ml there was a tendency to fewer symptoms after the low-lactose milk, although the difference was not significant (0.05 < p < 0.1). The new milk may be of potential usefulness in the treatment of protein calorie malnutrition in the developing countries, where lactose malabsorption is highly prevalent.     

Changes in plasma free fatty acid concentration following oral lactose tolerance tests as a test for lactose absorption in infants and children

Changes in blood glucose and plasma free fatty acid (FFA) following oral lactose tolerance tests (LTT) were measured in three groups of children. In three out of seventeen infants with secondary lactose intolerance, only a small increase (less than 25 mg/100 ml) in glucose was found, but a normal decline (more than 50% of fasting value) in FFA concentration occurred. Resumption of milk feeding proved that they were not intolerant to lactose. Six infants (37%) without lactose intolerance who were on a normal lactose-containing diet showed only small increases in glucose; five of them showed a normal decline in plasma FFA. Nine out of thirteen children with no symptoms following oral LTT failed to show an increase in blood glucose, while in only one there was a decline of less than 50% in FFA concentration. Our results suggest that measurement of plasma FFA following oral LTT may be a more reliable test for cleavage and absorption of lactose than LTT alone, but for the final evaluation of this test a study of larger groups is obviously needed.     

Calcium absorption from milk in lactase-deficient and lactase-sufficient adults

To determine whether lactose influences the absorption of calcium, the uptake of calcium from lactose-hydrolyzed milk and from unhydrolyzed milk was measured in 20 adults: 10 were lactase-deficient and 10 were lactase-sufficient as defined by breath hydrogen test, plasma glucose determination after oral lactose dose, and presence or absence of symptoms after lactose ingestion. On different days, each subject received either lactose-hydrolyzed or unhydrolyzed milk. Calcium absorption was measured by a double-isotope technique. In the lactase-deficient group, the mean absorptions were 33.5% from hydrolyzed milk and 36.2% from the same volume of unhydrolyzed milk (P greater than 0.30). In the lactase-sufficient group, mean absorptions were 24.2% from hydrolyzed milk and 25.7% from unhydrolyzed milk. The mean calcium absorption from both lactose-hydrolyzed milk and unhydrolyzed milk was significantly greater (P less than 0.01) in the lactase-deficient group compared to the lactase-sufficient group, presumably reflecting lower dietary calcium intake in the former. These data indicate that, in lactase-deficient subjects, malabsorption of lactose does not affect calcium absorption.     

Manifestation and occurrence of selective adult-type lactose malabsorption in Finnish teenagers

In 1969–1970, a simple random sample of 129 Finnish school-aged children was examined to study selective adult-type lactose malabsorption (SLM) in this age category. SLM was found in 8 children. All subjects were reexamined 5 years later. SLM was reconfirmed in these 8 persons and found in 3 additional subjects who had normal lactose absorption in the first examination. The prevalence of SLM was 9.3%, being 8.5% in the age category 12–15 years and 9.9% in that 16–20 years. Low rise of blood glucose in the lactose tolerance test of the first examination, very low milk consumption, milk intolerance, and history of gastrointestinal symptoms were found to be of low predictive value as indicators of SLM. It was also concluded that information about dietetic sources of lactose is important to persons with SLM, but categorical exclusion of lactose from the diet is not necessary, at least in the Finnish population.The study was supported by the Finnish Cultural Foundation and the Foundation for Pediatric Research in Finland.     

Hydrogen concentration in expired air analyzed with a new hydrogen sensor, plasma glucose rise, and symptoms of lactose intolerance after oral administration of 100 gram lactose

A rapid breath hydrogen analyzer to detect lactose malabsorption is described. After ingestion of a lactose solution the patient expires into a mouthpiece attached to a hydrogen sensor at 30-min intervals for 3 1/2 h. The hydrogen of the expired air causes a voltage change that can be transformed into ppm from a calibration curve. A tolerance test with a load of 100 g lactose was performed in 43 consecutive patients with various gastrointestinal disturbances, referred to the laboratory for the commonly used lactose tolerance test based on plasma glucose measurements. Eleven patients developed symptoms of lactose intolerance during the test. Biopsy specimens from the distal duodenum or proximal jejunum showed partial villous atrophy in one, in whom celiac disease with lactose intolerance was diagnosed; the other 10 had normal specimens. In nine of them lactose intolerance was diagnosed and confirmed by observation for months on a lactose-poor diet. The 10th patient (H.P.L.) did not improve on such a diet. He also showed pronounced symptoms of intolerance during a test with monosaccharides (glucose + galactose). His intestinal disease remained undiagnosed. The 11 patients with symptoms of intolerance and 3 patients without symptoms during the lactose load showed a flat plasma glucose curve after drinking the lactose solution--that is, a maximum rise of the glucose concentration of 1.5 mmol/l. One of the symptom-free patients dropped out and could not be observed, another did not improve on a lactose-poor diet, and the third noticed a favorable effect of the diet on stool consistency but not on other abdominal symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Breath testing to evaluate lactose intolerance in irritable bowel syndrome correlates with lactulose testing and may not reflect true lactose malabsorption

OBJECTIVES: An increased prevalence of lactose intolerance is seen in irritable bowel syndrome (IBS). Recently, we demonstrated a high prevalence of abnormal lactulose breath test results in IBS suggesting bacterial overgrowth. Because symptoms of lactose intolerance result from bacterial fermentation, the purpose of this study was to determine whether an abnormal lactose breath test is reflective of malabsorption or early presentation to bacteria. METHODS: Subjects with diarrhea-predominant IBS were enrolled. On day 1, subjects underwent a lactulose breath test after an overnight fast. Within 1 wk, subjects returned after fasting for a lactose breath test with simultaneous blood glucose measurements every 15 min to complete a lactose tolerance test (LTT). Symptoms were evaluated 3 h after lactose administration. RESULTS: Twenty subjects completed the study. One subject inadvertently received dextrose through the intravenous and was excluded. Of the remaining 19 subjects, three (16%) had an abnormal LTT suggesting malabsorption. In all, 10 subjects (53%) had an abnormal lactose breath test, 14 (74%) had an abnormal lactulose breath test, and 11 (58%) had symptoms after lactose administration. The agreement with symptoms was moderate (kappa = 0.47) and fair (kappa = 0.24) when compared to the lactose breath test and LTT, respectively. There was a fair correlation between lactose breath test and LTT (kappa = 0.29). However, lactose breath test hydrogen levels >166 ppm were universally predictive of abnormal LTT. Finally, a significant correlation was seen between the hydrogen production on lactose and lactulose breath test (r = 0.56, p = 0.01). CONCLUSIONS: Lactose breath testing in IBS subjects does not seem to reflect malabsorption; it may be an indicator of abnormal lactulose breath test, suggesting bacterial overgrowth.     

Breath hydrogen excretion after lactose and whole milk ingestion. A prospective comparison in lactase deficiency

As the 50 g of lactose in the usual clinical test is unphysiologic both because it is equivalent to 1 L milk and because the usual dietary intake is not the purified sugar, but milk, we undertook a prospective comparison of the absorption of lactose after both lactose and milk ingestion with an equivalent lactose content. We studied 51 healthy volunteers, using the hydrogen breath test technique. All patients received 25 g lactose in aqueous solution. Subjects with an abnormal test had the test repeated with 500 ml whole cow's milk, whereas subjects with a normal test repeated the test after ingesting the unabsorbable sugar lactulose to detect the capacity of their colonic flora to produce the gas. Symptoms of gastrointestinal intolerance were also recorded. Compared to an equivalent lactose amount, milk lactose is better absorbed (8% of the entire population malabsorbed 500 ml whole milk, whereas 33.33% malabsorbed 25 g lactose) and induces intolerance in fewer subjects. We conclude that milk rather than pure lactose must be used in clinical evaluation of lactose malabsorption and intolerance.     

Lactose tolerance in an Arab population

Lactose tolerance tests were performed on 67 adult Arab villagers. Fifty-four (80.6%) had a low rise in glucose and most had symptoms during the test. Lactose tolerance was not related to age or sex and did not correlate with milk consumption. A high incidence of adult lactose intolerance has been found in all Mediterranean groups studied to date—Greek Cypriots, Jews, and now Arabs.The authors wish to thank O. Mizrahy, PhD, of the Central Biochemical Laboratory of the Workers' Sick Fund, Tel-Aviv, for performing the blood sugar determinations; Mrs. Ora Ronen and Mr. Said Raby for valuable help in carrying out this study.     

Lactase deficiency in Jewish communities in Israel

Lactase deficiency and lactose tolerance were studied in several Jewish communities in Israel. Lactase deficiency was found in 60% of biopsied subjects. Forty-one biopsies were peroral and 22, surgical; histologically, the jejunal mucosa of all specimens was normal. Lactose tolerance tests were performed on 217 subjects, 118 patients and 99normals. A low glucose rise was found in 44.4% of Yemenites, 62.5% of North Africans (Sephardi), 72.2% of others (Sephardi), 79.2% of Ashkenazi, 84.2% of Iraqis and 85.0% of others (Oriental); the overall incidence was 71.1%. Statistical analysis confirmed that the population studied was heterogenous. Most subjects with a low glucose rise had symptoms during the test. Milk intake, low in almost all subjects, did not correlate with lactose tolerance. Most lactose intolerant subjects were not aware of milk intolerance; the condition is not usually symptomatic in Israel. Lactase deficiency in various population groups has been reviewed and evidence in favor of a genetic etiology emphasized.The authors wish to thank the staff of the Tel-Aviv Government Municipal Hospitals, in particular, the Department of Pediatrics-B for their help in carrying out this investigation and for permission to study their patients; Dr. A. Adam, Department of Human Genetics, Tel-Aviv University Medical School, for helpful advice and criticism. Blood sugar estimations were performed at the Central Biochemical Laboratory of the Workers Sick Fund, Tel-Aviv.     

Is lactose intolerance implicated in the development of post-infectious irritable bowel syndrome or functional diarrhoea in previously asymptomatic people?

OBJECTIVE: The relationship between lactose intolerance and post-infectious irritable bowel syndrome (IBS) in adults is uncertain. Bowel symptoms may persist after bacterial gastroenteritis and as post-infectious IBS. Acquired lactose intolerance may follow viral enteric infections in children. We compared the frequency of lactose intolerance after bacterial gastroenteritis in adults with and without symptoms of IBS or functional diarrhoea at 3-6-months' follow-up. DESIGN: A prospective cohort study was conducted. METHODS: All subjects with bacterial gastroenteritis confirmed by stool culture from the microbiology laboratory and without prior IBS or functional diarrhoea were eligible to participate. IBS and functional diarrhoea were diagnosed via self-completed Rome II modular questionnaires. Lactose intolerance was determined from a rise in breath hydrogen and plasma glucose and symptoms. RESULTS: One hundred and twenty-eight subjects with bacterial gastroenteritis were followed prospectively, from which a smaller cohort of 42 subjects took part in this study. The cohort was comprised of 24/25 subjects who developed post-infectious IBS (n = 16) or functional diarrhoea (n = 8) (9 male, 15 female) and 18 random controls (8 male, 10 female) chosen from the group without IBS or functional diarrhoea. The mean age of the subjects was 44.4 years (range 25-76 years). In the group with functional diarrhoea or IBS, four subjects had failure of the plasma glucose to rise but none had abnormal glucose hydrogen breath tests. In the control subjects, one had a positive combined test and six had failure of plasma glucose to rise alone. No subject developed symptoms during the test. CONCLUSIONS: Bacterial gastroenteritis did not cause persistent lactose intolerance in our study population. Lactose intolerance does not appear to be implicated in the aetiology of post-infectious bowel symptoms, including IBS. Advice to avoid dairy products in patients presenting with post-infectious IBS on the basis that they may have lactose intolerance appears unnecessary in patients from northern England.     

Incidence and Clinical Significance of Lactose Malabsorption in Adult Coeliac Disease

Fifty-one adult patients with coeliac disease, verified by a proximal small-intestinal biopsy, were investigated. Before treatment with a gluten-free and low-lactose diet 52% showed a slight rise in blood glucose during the lactose tolerance test. Seventy-nine per cent of these patients had watery stools, and 88% had three or more bowel movements a day—statistically significantly different from the coeliac patients with a normal lactose tolerance test. After treatment 12% had a flat lactose tolerance curve. Half of them (6%) had specific lactase deficiency. This is approximately the incidence of lactose malabsorption in the general Danish population. The small-intestinal disaccharidases and alkaline phosphatase levels were severely depressed before treatment. After treatment the activities increased, but not to normal. We conclude that lactose malabsorption is a clinically important condition in many patients with untreated coeliac disease, giving rise to more frequent and more watery stools. In well-treated coeliac disease lactose malabsorption is not commoner than in the general population. The lactose activity in a proximal intestinal biopsy specimen was found to be an unreliable indicator of lactose malabsorption in coeliac disease.     

Incidence and clinical significance of lactose malabsorption in adult coeliac disease

Fifty-one adult patients with coeliac disease, verified by a proximal small-intestinal biopsy, were investigated. Before treatment with a gluten-free and low-lactose diet 52% showed a slight rise in blood glucose during the lactose tolerance test. Seventy-nine per cent of these patients had watery stools, and 88% had three or more bowel movements a day--statistically significantly different from the coeliac patients with a normal lactose tolerance test. After treatment 12% had a flat lactose tolerance curve. Half of them (6%) had specific lactase deficiency. This is approximately the incidence of lactose malabsorption in the general Danish population. The small-intestinal disaccharidases and alkaline phosphatase levels were severely depressed before treatment. After treatment the activities increased, but not to normal. We conclude that lactose malabsorption is a clinically important condition in many patients with untreated coeliac disease, giving rise to more frequent and more watery stools. In well-treated coeliac disease lactose malabsorption is not commoner than in the general population. The lactose activity in a proximal intestinal biopsy specimen was found to be an unreliable indicator of lactose malabsorption in coeliac disease.     

Lactose malabsorption in adult patients with Crohn's disease

In order to evaluate, in adult patients with Crohn's disease (CD), the prevalence of lactose malabsorption and intolerance, and the percentage who can tolerate a physiologic amount of milk in their diet, we tested 37 patients with CD (19 with intestinal resection, and 18 without) and 67 healthy controls (C) with the H2-breath test after they had ingested increasing loads of lactose as 10% solution (12.5 g, 25 g, and 50 g). Patients with malabsorption after the 12.5-g dose were tested further with 250 ml of milk. In the total group of patients and in the subgroup of those with resection, the prevalence of malabsorption was higher than in controls at all lactose loads; in patients who had not undergone resection, no significant difference was observed with the 12.5-g dose. Eleven of 18 patients who were malabsorbers with the 12.5-g dose had malabsorption also with 250 ml milk; however, only three of them (8% of the total group) experienced symptoms of intolerance. We conclude that, in adult patients with CD, 1) the prevalence of lactose malabsorption is increased, 2) in patients who have undergone intestinal resection, malabsorption occurs at a lower dose of the sugar than in patients who did not, and 3) since only 8% of patients experienced symptoms of intolerance after the ingestion of milk 250 ml, this amount can be empirically inserted in the daily diet of an adult with CD.     

Applicability of short hydrogen breath test for screening of lactose malabsorption

The gold standard for diagnosing lactose malabsorption is the H₂ hydrogen breath test (HBT). Different methods of HBT have been proposed. However, in clinical practice the HBT is often shortened to 1–2 hr without proper validation. Our objective was to establish whether the usefulness of the HBT is influenced by shortening of the test and/or by substrate variations. In 62 patients with clinically suspected lactose intolerance and a positive lactose HBT we calculated the sensitivity of the HBT depending on the duration of the HBT. To determine whether substrate variations influence the sensitivity of the HBT, in another group of 32 patients with clinically suspected lactose intolerance and a positive milk HBT, the sensitivity of the HBT was also calculated depending on the duration of the test after milk ingestion. In other unselected 97 individuals, the result of the HBT with 360 ml of whole milk supplemented with lactose was compared with a symptomatic score for lactose intolerance to evaluate the specificity of the shortened milk HBT. Breath H₂ excretion was significantly higher after lactose than after milk load (P < 0.01), and the increase in H₂ appeared earlier with lactose than with milk (60 vs 90, min respectively). HBT duration influenced the sensitivity of the test that decreased from 95% for the 3-hr HBT to 37% for the 1-hr HBT with lactose and from 80% for 3-hr HBT to 21% for 1-hr HBT with milk. The specificity was similar for the 3-hr milk HBT and the 5-hr test (67 vs 62%). In conclusion, for screening of lactose malabsorption, the HBT can be shortened to 3 hr without loss of sensitivity and specificity, when a high dose of lactose load is used.