Acta Paediatr 81: 598-600. 1992
The status of lactose absorption in Hong Kong Chinese children K Tadesse, DTY Leung’ and RCF Yuen Departments of Physiology and Paediatrics‘ The Chinese University of Hong Kong, Hong Kong
Tadesse K, Leung DTY, Yeun RCF. The status of lactose absorption in Hong Kong Chinese children. Acta Paediatr 1992;81598-600. Stockholm. ISSN 0803-5253 Lactose malabsorption was investigated in 169 Chinese children aged between two and 16 years using the breath hydrogen test. The challenge was either lactose solution (1 g/kg) or cow’s milk (10 ml/kg). Overall, 68% of the children showed a significant increase in breath hydrogen following the lactose challenge while only 17% showed an increase after the cow’s milk challenge and 13% after both challenges. The number of malabsorbers increased significantly ( p < 0.001) with age and no associated gastrointestinal symptoms or signs were found in any of the children following the challenges, suggesting a gradual and partial loss of intestinal lactase activity. We conclude that the prevalence of lactose malabsorption in Hong Kong children is very high using the standard lactose tolerance test but when a more realistic amount of lactose and a natural medium such as a glass of milk is used as the challenge, the number of malabsorbers becomes small and clinically insignificant. 0 Breath hydrogen test, lactase dejkiency. lactose intolerance, lactose maIabsorption, lactose tolerance test K Tadesse. Department of Physiology, The Chinese University of Hong Kong. Shatin, N.T.. Hong Kong
Specific intestinal lactase activity declines with age in all mammals including man (1). As a result the prevalence of primary (adult-onset) lactose malabsorption in most population groups, particularly in East Asia, is very high (2, 3). From the few studies in Asia it appears that, in fact, the condition has an early onset and is not uncommon in younger children. A study in Japan (4) showed an incidence of approximately 30% in children as young as three years old increasing to 85% by six years of age and 90% in adult life. Similar incidence rates have also been observed in Thailand (9,China (6) and Taiwan (7). In fact Chang et al. (7), found that about 1 1 % of Taiwanese children less than two years old showed signs of malabsorption to their challenge. To date, there has been no study in the Hong Kong paediatric age group but a study in adult Chinese found laboratory signs of malabsorption in 65% of the subjects, even with a challenge of 5 ml/kg body weight cow’s milk (i.e. approximately 0.25 g lactose per kg) (8). However, despite the high prevalence of the condition its presentation as a clinical problem is very low. This may be either because of instinctive avoidance of milk and milk products from the diet or alternatively the loss of intestinal enzyme activity is not total. There is evidence to support both hypotheses (9, 10). Recently, paediatricians in Hong Kong became concerned because of the declining habit of breast feeding coupled with an increasing trend towards bottle feeding with infant formula for a longer period of time. It is not uncommon to find children of more than one year of age taking 300-600 ml of milk each day (1 I). Of equal concern is the fact that despite remarkable socioeconomic advancement, acute gastroenteritis still
accounts for 10% of paediatric admissions and was the second most common diagnosis in one general practice ( 1 2, 13). Secondary lactose malabsorption is commonly associated with acute gastroenteritis and in communities with underlying low levels of intestinal lactase activity the risk of aggravating the situation could be higher. This will have implications on morbidity and management. The purposes of this study were to determine the prevalence of primary lactose malabsorption in the paediatric age group, the age of onset, and the factors which may influence symptom development. Preliminary results of this study have been communicated at a meeting of the Physiological Society (UK) and appeared as an abstract (14).
Subjects and methods Healthy children between the ages of 2 and 16 years from a local children’s home were recruited and the study conducted between 1988 and 1989. The children were fasted from their evening meal to the following morning when they were challenged with either a 10% lactose solution of 1 g/kg body weight (50 g maximum) or cow’s milk 10 ml/kg body weight (i.e. approximately 0.5 g/kg lactose). The two tests were performed randomly and on separate days. Lactose malabsorption was assessed by measuring the concentration of hydrogen in breath samples using an exhaled hydrogen monitor with an electrochemical detector (GMI Medical Ltd, Inchinnan Estate, Renfrew, Scotland). Endexpiratory breath samples were obtained in duplicate immediately before the challenge and half-hourly there-
Lactose malabsorption in Hong Kong
ACTA PKDIATR 81 (1992)
Table I . Characteristicsof the children studied (n = 169) (mean f SEM and range).
Sex Female Male
Table 3. Age distribution of children with signs of malabsorption (i.e. hydrogen >20 ppm) after challenge with either lactose ( 1 g/kg body weight) or cow’s milk (10 ml/kg body weight).
70 (41)* 99 (59)
Age (years) Weight (kg)
Lactose No. tested
18
17 (41)* 13 (65) 16 (80) 16 (94) 17 (94)
37 23 13 25 17
5 (39) 7 (28) 6 (35)
117
79 (68)
115
20 (17)
Age (years)
No. tested
23.2 8.6
3-4 5-6 7-8 9-10 11-12
42 20 20
Total
* Numbers in parentheses are percentages.
Milk
Positive
7.89f3.33 (2.54-16.21) (1 1.2-52.3)
599
17
Positive 2 (5) -
* Numbers in parentheses are percentages. Table 2. Results of breath hydrogen test after challenge with a 10% lactose solution (1 g/kg body weight) or cow’s milk (10 ml/kg body weight).
NO. positive No. positive No. positive Challenge No. tested (> 20 ppm”) (20 ppm > BLb) (10 ppm 2 BL) Lactose Milk Both a
117 115 86
79 (68)* 20(17) 1 1 (13)
74 (63) 15 (13) 8 (9)
82 (70) 19 (17) 12 (14)
ppm =parts per million; bBL=baseline value.
* Numbers in parentheses are percentages.
after for the following 3 h. The samples were analysed on the same day. Symptoms and signs which developed during the test were also recorded. The study was approved by the Ethics Committee of our institution and informed consent was obtained from the children’s legal guardians. Three different criteria were used to define malabsorption: ( I ) the conventional method of a sustained increase in breath hydrogen to 20 parts per million (ppm) or above, within 3 h after the challenge; (2) a more stringent criterium of an increase of 2 20 ppm above the baseline value within 3 h after the challenge; and (3) an increase of 2 10 ppm above the baseline value following the challenge, which has been advocated by some workers recently. Results are presented as mean and SEM or as number and percentage positive to the challenge. Statistical evaluation was performed using the chi-square test.
included in the analysis. The number of children less than three years and more than 13 years of age were very few, making statistical analysis difficult and so they were excluded. There were 232 subjects who satisfied the criteria of which 117 had lactose, 115 milk and 86 both challenges. Using the conventional criterium of breath hydrogen 2 2 0 ppm, 68% of the 117 children given the lactose challenge showed a significant increase within 3 h following the challenge indicating malabsorption. In contrast, when an equivalent amount of milk but with half the lactose content was used, only 17% showed a significant increase. Of the 86 children who undertook both the lactose and milk challenge, 1 1 (13%) showed a significant increase in breath hydrogen to both challenges. Using the other two criteria did not significantly alter the percentage of malabsorbers (Table 2). None of the children reported any gastrointestinal symptoms following the administration of either the lactose solution or the milk. As shown in Table 3, the number of lactose malabsorbers increased significantly ( p < 0.001) with age and this condition started early on in life in some children. At 3-4 years of age about 40% of the children showed a significant increase in breath hydrogen excretion after the standard lactose tolerance test, rising to approximately 94% at 9-10 years of age and stabilizing after 10 years of age. Although the percentage of children with a significant increase in breath hydrogen indicating some malabsorption of lactose was much smaller with the milk challenge, the age-related increase in the number of malabsorbers was still observed ( p < 0.001).
Results One hundred and sixty-nine children participated in the experiment. The age and sex distribution of the children are shown in Table 1. All the children excreted detectable levels of hydrogen in their breath and this was taken as an indication of their ability to produce hydrogen. A total of 305 challenges were performed and only test results with a baseline hydrogen value of < 20 ppm were
Discussion As expected, using the standard lactose tolerance test the incidence of lactose malabsorption in the paediatric age group in Hong Kong was very high. This finding is in agreement with a number of similar investigations from this region and elsewhere, but the lack of accompanying
600
K Tadesse et al.
symptoms and signs in the children who were malabsorbers was a surprise (4,5,7,15). The amount of lactose administered may explain partly the total lack of symptoms, yet other studies using the same dose have reported some symptom development (7, 15, 16). Another factor may be the partial and gradual loss of lactase specific activity, as has previously been reported (7, 17) and indirectly demonstrated in this study (Table 3). In such a situation symptom development would be expected to be directly related to the remaining level of activity and the degree of malabsorption it causes. However, the very subjectiveness and variability of awareness of discomfort, particularly in children, would make it unwise to speculate further on this observation. The paucity of clinically manifest cases of primary lactose malabsorption in the paediatric age group in our community is not well explained. It has been attributed previously to milk and milk products not accounting for a significant part of the Chinese diet after weaning. This may have been true before and may apply to a certain section of the population at present, as was confirmed in the institution where our subjects come from, where milk and milk products did not constitute a significant part of the regular diet of the children. However, the same may not apply to the general population, since studies have shown that most of the young children in Hong Kong are fed with milk formula and for a longer period of time after weaning than before and the older children’s access to milk and milk products is increasing ( I I , 18). In fact, the consumption of dairy products between 1978 and 1988 had trebled while the population has only increased by less than 10% (18). A plausible explanation to the paucity of clinical cases may be the lack of gastrointestinal symptoms and signs associated with an intake of small amounts of milk. It is conceivable, as has been observed in other communities, that most children adjust their intake to suit their tolerance limit, without being aware of it, and would not develop repeated and regular symptoms requiring medical attention (15). It is also possible that because of the partial and gradual loss of lactase activity, the probability of developing unbearable symptoms after milk ingestion would be less. From the findings in this study it appears that the level at which the criteria for a positive breath hydrogen test are set will not make a significant difference to the outcome. As long as a low baseline is established before the challenge and a steady and consistent increase is observed within 3 h after the challenge, the chance of error is minimal. Finally, in the investigation of this condition we would encourage the use of a realistic amount of milk challenge instead of a lactose solution. The so called “standard” test has been shown repeatedly to be inappropriate since it does not evaluate the ability to handle physiological amounts of milk and the dose used has no relation to the amount of lactose an individual is exposed to in a standard meal or at a given time (1 9,20).
ACTA PRDIATR 81 (1992)
The amount, form and frequency of intake has been shown to influence the development of symptoms and signs (10, 15, 16). Thus, it is unreasonable to use a test which overwhelms the system in most people and the result of which is at best of no practical value. to the doctor and patient, and at worst could lead to a misdiagnosis of other gastrointestinal disorders (1 0). Acknowledgements.-The authors are grateful to the United College Endowment Fund, CUHK for financial assistance and the staff of St Christopher’s Children Home for their unremitting cooperation. The excellent technical assistance of Miss WC Li is much appreciated.
References 1. Johnson JD, Kretchmer N, Simoons FJ. Lactose malabsorption:
Its biology and history. Adv Pediatr 1974;21:197-237 2. Ransome-Kuti 0.Lactose intolerance-a review. Postgrad Med J (SUPPI2) 1977;53:73-83 3. Tadesse K, Leung DTY. Lactose malabsorption and intolerance in the Far East. Hong Kong J Paediatr 1990;7:3949 4. Nose 0, Iida Y. Kai H, Harada T. Oaawa M. Yabuuchi H. Breath hydrogen test for detecting lactose malabsorption in infants and children: Prevalence of lactose malabsorption in Japanese children and adults. Arch Dis Child 1979;54:43640 5 Keusch GT, Troncale FJ, Miller LH, Promadhat V, Anderson PR. Acquired lactose malabsorption in Thai children. Pediatrics 1969;43:540-5 6 Yao X-H, Kong B-Q, Yan J-X, Zhu X-C. Lactose tolerance test by hydrogen breath method in Chinese. Chin Med J (Engl) 1987;1OO:3 16-18 7. Chang M-H, Hsu H-Y, Chen C-J, Lee C-H, Hsu J-Y. Lactose malabsorption and small-intestinal lactase in normal Chinese children. J Pediatr Gastroenterol Nutr 1987;6:369-72 8. Tadesse K. Intestinal lactase activity in Hong Kong Chinese. J Physiol 1985;365:108P 9. Kretchmer N. Lactose and lactase-A historical perspective. Gastroenterology 1971;61:805- I3 10. Newcomer AD, McGill DB. Clinical importance of lactase deficiency. N Engl J Med 1984;310:42-3 11. Li AMC, Baber FM, Yu AMC, Leung VS. The weaning diet of Hong Kong Children. J Hong Kong Med Assoc 1985;167-75 12. Leung DTY, Tseng TYM, Davies DP. Setting up a clinical audit of paediatric morbidity in Hong Kong: Some early experiences. Aust Paediatr J 1987;111-3 13. Tong EKM W. Morbidity patterns in community health centre-a two year survey. Hong Kong Practitioner 1985; 1301-5 14. Leung DTY, Tadesse K, Yuen RCF. Lactose malabsorption in Hong Kong Chinese children. J Physiol 1988;407:23P 15. Scrimshaw NS, Murray EB. The acceptability of milk and milk products in populations with a high prevalence of lactose intolerance. Am J Clin Nutr 1988;48(Suppl):1083- I59 16. Garza C, Scrimshaw NS. Relationship of lactose intolerance to milk intolerance in young children. Am J Clin Nutr 1976;29:192-6 17. Buller HA, Van Wassenaer AG, Raghavan S, Montgomery RK, Sybicki MA, Grand RJ. New insights into lactase and glycosylceramidase activities of rat lactase-phlorizin hydrolase. Am J Physiol 1989;257:G616-23 18. Census and Statistics Department (Hong Kong Government). Statistical Sources. Hong Kong: Government Printer, 1989 19. de Villiers CPR. A standardized milk tolerance test. J Clin Gastroenterol 1987;9:320-3 20. Tadesse K. A modified lactose tolerance test for determining the degree of lactose malabsorption in an individual. J Hum Nutr Diet 1989;2:339-43 Received May 28, 1990. Accepted Oct. 17, 1991
The status of lactose absorption in Hong Kong Chinese children K Tadesse, DTY Leung’ and RCF Yuen Departments of Physiology and Paediatrics‘ The Chinese University of Hong Kong, Hong Kong
Tadesse K, Leung DTY, Yeun RCF. The status of lactose absorption in Hong Kong Chinese children. Acta Paediatr 1992;81598-600. Stockholm. ISSN 0803-5253 Lactose malabsorption was investigated in 169 Chinese children aged between two and 16 years using the breath hydrogen test. The challenge was either lactose solution (1 g/kg) or cow’s milk (10 ml/kg). Overall, 68% of the children showed a significant increase in breath hydrogen following the lactose challenge while only 17% showed an increase after the cow’s milk challenge and 13% after both challenges. The number of malabsorbers increased significantly ( p < 0.001) with age and no associated gastrointestinal symptoms or signs were found in any of the children following the challenges, suggesting a gradual and partial loss of intestinal lactase activity. We conclude that the prevalence of lactose malabsorption in Hong Kong children is very high using the standard lactose tolerance test but when a more realistic amount of lactose and a natural medium such as a glass of milk is used as the challenge, the number of malabsorbers becomes small and clinically insignificant. 0 Breath hydrogen test, lactase dejkiency. lactose intolerance, lactose maIabsorption, lactose tolerance test K Tadesse. Department of Physiology, The Chinese University of Hong Kong. Shatin, N.T.. Hong Kong
Specific intestinal lactase activity declines with age in all mammals including man (1). As a result the prevalence of primary (adult-onset) lactose malabsorption in most population groups, particularly in East Asia, is very high (2, 3). From the few studies in Asia it appears that, in fact, the condition has an early onset and is not uncommon in younger children. A study in Japan (4) showed an incidence of approximately 30% in children as young as three years old increasing to 85% by six years of age and 90% in adult life. Similar incidence rates have also been observed in Thailand (9,China (6) and Taiwan (7). In fact Chang et al. (7), found that about 1 1 % of Taiwanese children less than two years old showed signs of malabsorption to their challenge. To date, there has been no study in the Hong Kong paediatric age group but a study in adult Chinese found laboratory signs of malabsorption in 65% of the subjects, even with a challenge of 5 ml/kg body weight cow’s milk (i.e. approximately 0.25 g lactose per kg) (8). However, despite the high prevalence of the condition its presentation as a clinical problem is very low. This may be either because of instinctive avoidance of milk and milk products from the diet or alternatively the loss of intestinal enzyme activity is not total. There is evidence to support both hypotheses (9, 10). Recently, paediatricians in Hong Kong became concerned because of the declining habit of breast feeding coupled with an increasing trend towards bottle feeding with infant formula for a longer period of time. It is not uncommon to find children of more than one year of age taking 300-600 ml of milk each day (1 I). Of equal concern is the fact that despite remarkable socioeconomic advancement, acute gastroenteritis still
accounts for 10% of paediatric admissions and was the second most common diagnosis in one general practice ( 1 2, 13). Secondary lactose malabsorption is commonly associated with acute gastroenteritis and in communities with underlying low levels of intestinal lactase activity the risk of aggravating the situation could be higher. This will have implications on morbidity and management. The purposes of this study were to determine the prevalence of primary lactose malabsorption in the paediatric age group, the age of onset, and the factors which may influence symptom development. Preliminary results of this study have been communicated at a meeting of the Physiological Society (UK) and appeared as an abstract (14).
Subjects and methods Healthy children between the ages of 2 and 16 years from a local children’s home were recruited and the study conducted between 1988 and 1989. The children were fasted from their evening meal to the following morning when they were challenged with either a 10% lactose solution of 1 g/kg body weight (50 g maximum) or cow’s milk 10 ml/kg body weight (i.e. approximately 0.5 g/kg lactose). The two tests were performed randomly and on separate days. Lactose malabsorption was assessed by measuring the concentration of hydrogen in breath samples using an exhaled hydrogen monitor with an electrochemical detector (GMI Medical Ltd, Inchinnan Estate, Renfrew, Scotland). Endexpiratory breath samples were obtained in duplicate immediately before the challenge and half-hourly there-
Lactose malabsorption in Hong Kong
ACTA PKDIATR 81 (1992)
Table I . Characteristicsof the children studied (n = 169) (mean f SEM and range).
Sex Female Male
Table 3. Age distribution of children with signs of malabsorption (i.e. hydrogen >20 ppm) after challenge with either lactose ( 1 g/kg body weight) or cow’s milk (10 ml/kg body weight).
70 (41)* 99 (59)
Age (years) Weight (kg)
Lactose No. tested
18
17 (41)* 13 (65) 16 (80) 16 (94) 17 (94)
37 23 13 25 17
5 (39) 7 (28) 6 (35)
117
79 (68)
115
20 (17)
Age (years)
No. tested
23.2 8.6
3-4 5-6 7-8 9-10 11-12
42 20 20
Total
* Numbers in parentheses are percentages.
Milk
Positive
7.89f3.33 (2.54-16.21) (1 1.2-52.3)
599
17
Positive 2 (5) -
* Numbers in parentheses are percentages. Table 2. Results of breath hydrogen test after challenge with a 10% lactose solution (1 g/kg body weight) or cow’s milk (10 ml/kg body weight).
NO. positive No. positive No. positive Challenge No. tested (> 20 ppm”) (20 ppm > BLb) (10 ppm 2 BL) Lactose Milk Both a
117 115 86
79 (68)* 20(17) 1 1 (13)
74 (63) 15 (13) 8 (9)
82 (70) 19 (17) 12 (14)
ppm =parts per million; bBL=baseline value.
* Numbers in parentheses are percentages.
after for the following 3 h. The samples were analysed on the same day. Symptoms and signs which developed during the test were also recorded. The study was approved by the Ethics Committee of our institution and informed consent was obtained from the children’s legal guardians. Three different criteria were used to define malabsorption: ( I ) the conventional method of a sustained increase in breath hydrogen to 20 parts per million (ppm) or above, within 3 h after the challenge; (2) a more stringent criterium of an increase of 2 20 ppm above the baseline value within 3 h after the challenge; and (3) an increase of 2 10 ppm above the baseline value following the challenge, which has been advocated by some workers recently. Results are presented as mean and SEM or as number and percentage positive to the challenge. Statistical evaluation was performed using the chi-square test.
included in the analysis. The number of children less than three years and more than 13 years of age were very few, making statistical analysis difficult and so they were excluded. There were 232 subjects who satisfied the criteria of which 117 had lactose, 115 milk and 86 both challenges. Using the conventional criterium of breath hydrogen 2 2 0 ppm, 68% of the 117 children given the lactose challenge showed a significant increase within 3 h following the challenge indicating malabsorption. In contrast, when an equivalent amount of milk but with half the lactose content was used, only 17% showed a significant increase. Of the 86 children who undertook both the lactose and milk challenge, 1 1 (13%) showed a significant increase in breath hydrogen to both challenges. Using the other two criteria did not significantly alter the percentage of malabsorbers (Table 2). None of the children reported any gastrointestinal symptoms following the administration of either the lactose solution or the milk. As shown in Table 3, the number of lactose malabsorbers increased significantly ( p < 0.001) with age and this condition started early on in life in some children. At 3-4 years of age about 40% of the children showed a significant increase in breath hydrogen excretion after the standard lactose tolerance test, rising to approximately 94% at 9-10 years of age and stabilizing after 10 years of age. Although the percentage of children with a significant increase in breath hydrogen indicating some malabsorption of lactose was much smaller with the milk challenge, the age-related increase in the number of malabsorbers was still observed ( p < 0.001).
Results One hundred and sixty-nine children participated in the experiment. The age and sex distribution of the children are shown in Table 1. All the children excreted detectable levels of hydrogen in their breath and this was taken as an indication of their ability to produce hydrogen. A total of 305 challenges were performed and only test results with a baseline hydrogen value of < 20 ppm were
Discussion As expected, using the standard lactose tolerance test the incidence of lactose malabsorption in the paediatric age group in Hong Kong was very high. This finding is in agreement with a number of similar investigations from this region and elsewhere, but the lack of accompanying
600
K Tadesse et al.
symptoms and signs in the children who were malabsorbers was a surprise (4,5,7,15). The amount of lactose administered may explain partly the total lack of symptoms, yet other studies using the same dose have reported some symptom development (7, 15, 16). Another factor may be the partial and gradual loss of lactase specific activity, as has previously been reported (7, 17) and indirectly demonstrated in this study (Table 3). In such a situation symptom development would be expected to be directly related to the remaining level of activity and the degree of malabsorption it causes. However, the very subjectiveness and variability of awareness of discomfort, particularly in children, would make it unwise to speculate further on this observation. The paucity of clinically manifest cases of primary lactose malabsorption in the paediatric age group in our community is not well explained. It has been attributed previously to milk and milk products not accounting for a significant part of the Chinese diet after weaning. This may have been true before and may apply to a certain section of the population at present, as was confirmed in the institution where our subjects come from, where milk and milk products did not constitute a significant part of the regular diet of the children. However, the same may not apply to the general population, since studies have shown that most of the young children in Hong Kong are fed with milk formula and for a longer period of time after weaning than before and the older children’s access to milk and milk products is increasing ( I I , 18). In fact, the consumption of dairy products between 1978 and 1988 had trebled while the population has only increased by less than 10% (18). A plausible explanation to the paucity of clinical cases may be the lack of gastrointestinal symptoms and signs associated with an intake of small amounts of milk. It is conceivable, as has been observed in other communities, that most children adjust their intake to suit their tolerance limit, without being aware of it, and would not develop repeated and regular symptoms requiring medical attention (15). It is also possible that because of the partial and gradual loss of lactase activity, the probability of developing unbearable symptoms after milk ingestion would be less. From the findings in this study it appears that the level at which the criteria for a positive breath hydrogen test are set will not make a significant difference to the outcome. As long as a low baseline is established before the challenge and a steady and consistent increase is observed within 3 h after the challenge, the chance of error is minimal. Finally, in the investigation of this condition we would encourage the use of a realistic amount of milk challenge instead of a lactose solution. The so called “standard” test has been shown repeatedly to be inappropriate since it does not evaluate the ability to handle physiological amounts of milk and the dose used has no relation to the amount of lactose an individual is exposed to in a standard meal or at a given time (1 9,20).
ACTA PRDIATR 81 (1992)
The amount, form and frequency of intake has been shown to influence the development of symptoms and signs (10, 15, 16). Thus, it is unreasonable to use a test which overwhelms the system in most people and the result of which is at best of no practical value. to the doctor and patient, and at worst could lead to a misdiagnosis of other gastrointestinal disorders (1 0). Acknowledgements.-The authors are grateful to the United College Endowment Fund, CUHK for financial assistance and the staff of St Christopher’s Children Home for their unremitting cooperation. The excellent technical assistance of Miss WC Li is much appreciated.
References 1. Johnson JD, Kretchmer N, Simoons FJ. Lactose malabsorption:
Its biology and history. Adv Pediatr 1974;21:197-237 2. Ransome-Kuti 0.Lactose intolerance-a review. Postgrad Med J (SUPPI2) 1977;53:73-83 3. Tadesse K, Leung DTY. Lactose malabsorption and intolerance in the Far East. Hong Kong J Paediatr 1990;7:3949 4. Nose 0, Iida Y. Kai H, Harada T. Oaawa M. Yabuuchi H. Breath hydrogen test for detecting lactose malabsorption in infants and children: Prevalence of lactose malabsorption in Japanese children and adults. Arch Dis Child 1979;54:43640 5 Keusch GT, Troncale FJ, Miller LH, Promadhat V, Anderson PR. Acquired lactose malabsorption in Thai children. Pediatrics 1969;43:540-5 6 Yao X-H, Kong B-Q, Yan J-X, Zhu X-C. Lactose tolerance test by hydrogen breath method in Chinese. Chin Med J (Engl) 1987;1OO:3 16-18 7. Chang M-H, Hsu H-Y, Chen C-J, Lee C-H, Hsu J-Y. Lactose malabsorption and small-intestinal lactase in normal Chinese children. J Pediatr Gastroenterol Nutr 1987;6:369-72 8. Tadesse K. Intestinal lactase activity in Hong Kong Chinese. J Physiol 1985;365:108P 9. Kretchmer N. Lactose and lactase-A historical perspective. Gastroenterology 1971;61:805- I3 10. Newcomer AD, McGill DB. Clinical importance of lactase deficiency. N Engl J Med 1984;310:42-3 11. Li AMC, Baber FM, Yu AMC, Leung VS. The weaning diet of Hong Kong Children. J Hong Kong Med Assoc 1985;167-75 12. Leung DTY, Tseng TYM, Davies DP. Setting up a clinical audit of paediatric morbidity in Hong Kong: Some early experiences. Aust Paediatr J 1987;111-3 13. Tong EKM W. Morbidity patterns in community health centre-a two year survey. Hong Kong Practitioner 1985; 1301-5 14. Leung DTY, Tadesse K, Yuen RCF. Lactose malabsorption in Hong Kong Chinese children. J Physiol 1988;407:23P 15. Scrimshaw NS, Murray EB. The acceptability of milk and milk products in populations with a high prevalence of lactose intolerance. Am J Clin Nutr 1988;48(Suppl):1083- I59 16. Garza C, Scrimshaw NS. Relationship of lactose intolerance to milk intolerance in young children. Am J Clin Nutr 1976;29:192-6 17. Buller HA, Van Wassenaer AG, Raghavan S, Montgomery RK, Sybicki MA, Grand RJ. New insights into lactase and glycosylceramidase activities of rat lactase-phlorizin hydrolase. Am J Physiol 1989;257:G616-23 18. Census and Statistics Department (Hong Kong Government). Statistical Sources. Hong Kong: Government Printer, 1989 19. de Villiers CPR. A standardized milk tolerance test. J Clin Gastroenterol 1987;9:320-3 20. Tadesse K. A modified lactose tolerance test for determining the degree of lactose malabsorption in an individual. J Hum Nutr Diet 1989;2:339-43 Received May 28, 1990. Accepted Oct. 17, 1991
