Lactose maldigestion in Ascaris-infected

Downloaded from by guest on August 6, 2013
breath
Introduction The ability to digest lactose beyond childhood seems to be peculiar to most northern European and white American ethnic groups (1). Although low mucosal lactase levels and some degree of lactose maldigestion undoubtedly exists in many children in African, Asian, and Latin American origin (2-4), there is evidence to show that they can consume nutritionally useful quantities of milk without developing serious symptoms (5, 6). However, if other factors such as superimposed gastrointestinal infections interfere with lactose utilization, the public health importance increases considerably since milk is a major food in childhood and in programs of nutritional supplementation (7). Ascaris lumbricoides (roundworm) has been estimated to infect nearly 1000 million people (8) many of whom are undernourished children from tropical countries. AlThe American Journal of Clinical Nutrition 39: FEBRUARY © 1984 American Society for Clinical Nutrition
256
CARRERA
ET
AL
measured by changes in plasma glucose after an oral lactose load in Ascaris-infected pigs compared with uninfected controls (18). Plasma glucose reached normal levels during a second lactose tolerance test 3 wk after anthelmintic treatment. The measurements made during the experimental work with pigs suggested the possibility that children infected with A lumbricoides might experience lactose maldigestion. Herein, we describe two studies carried out to investigate 1) the contribution of A lumbricoides to lactose maldigestion in preschool children, and 2) the improvement in the ability of children to digest actose after anthelmintic treatment. Materials
though not a universal finding, enough evidence has now been obtained to demonstrate that under certain conditions and in certain communities the presence of Ascaris in children affects adversely their nutritional status (9-16). Recently, Forsum et al (17) observed decreased lactase activity of the mucosa of the small intestine as well as lactose maldigestion in young protein-deficient pigs infected with Ascaris suum. This parasite is very similar to A lumbricoides of man in terms of size, morphology, and life cycle. Further experiments with the pig-Ascaris system have confirmed reduced lactose digestion as
Lactose maldigestion preschool children’2
Eduvigis Carrera, MD, Malden
in Ascaris-infected
PhD, and David WT Crompton, P/iD, ScD
C Nesheim,
ABSTRACT Two studies were conducted to investigate the contribution of Ascaris lumbricoides to lactose maldigestion in preschool children in two different communities in Panama where milk is available as a source of nutrients and the prevalence of Ascaris is known to be high. Both Ascaris-infected and uninfected children were given a standard lactose load and lactose absorption was studied by measuring the rise in plasma glucose in study 1 and by determination of breath hydrogen concentrations at regular intervals after ingestion of the test dose in study 2. All children were tested before anthelmintic treatment with levamisole and 3 wk after therapy. The mean rise in blood glucose from infected (n = 13) children 40 mm after the ingestion of lactose was about half of that of the controls (n = 21). After deworming, lactose digestion improved in previously infected children. In study 2, significant differences in breath hydrogen concentrations postmilk ingestion were observed between the Ascaris-infected (n = 47) and the uninfected children (n = 35) before treatment. There was a substantial reduction of breath hydrogen after milk ingestion in the previously infected children after therapy. No differences were observed in breath hydrogen content of the uninfected children during the preand posttreatment phases of the study in the lactose tolerance test. These studies provide evidence that infection with Ascaris lumbricoides impairs lactose digestion in preschool children. Am iC/in Nutr I 984;39:255-264. KEY WORDS sitic infection, Milk intolerance, hydrogen Ascaris /umbricoides, lactose tolerance, levamisole, para-
‘From the Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853 and The Molteno Institute of Parasitology, Cambridge University, Cambridge, Enland CB2 3EE. Address reprint requests to: Dr MC Nesheim, Division of Nutritional Sciences, Cornell University, Savage Hall, Ithaca, NY 14853. Received March 31, 1983. Accepted for publication August 30, 1983. 1984, pp 255-264 Printed in U.S.A. 255