Correlation of lactase activity, lactose tolerance and milk consumption in different age groups

Abstract

Small intestinal lactase activity in the health adult is either the same as in early infancy or may drop to very low levels. The behavior of the enzymatic state varies with the ethnic group studied. In those adults with low lactase activity little information is availalbe as to the age at which the lactase decreases. We attempted to determine a) the frequency of low intestinal lactase activity and b) the age at which the change occurs. For this purpose we reviewed in a large number of intestinal biopsies both histologically as well as for disaccharidase activities. The biopsies were obtained from a heterogeneous group of Caucasians, including patients, their siblings and parents. The patients were those with failure to thrive in whom no organic cause could be elicited, and those with the irritable colon syndrome. Patients ranged in age from 6 weeks to 50 years and out of a total of 1, 077 jejunal biopsies, 172 morphologically normal biopsies were selected. The milk drinking habits of 118 subjects and their families were elicited and 31 oral lactose tolerance tests performed. The mucosal lactase activity and sucrase-to-lactase ratio in those 172 individuals were plotted against age. In the first 3 years the mean lactase activity was 32.1 plus or minus 10.1 mumoles/g protein per min and the sucrase-to-lactase ratio was 1.7 plus or minus 0.5 with no change from year to year. However, after age 5 two separate groups emerge. A small group (24.6% of the population) with low lactase activity, and a second group possessing the same mean value for lactase activity as noted in the first 3 years. The low lactase activity group included children and adults with clinical lactose intolerance. These individuals consumed relatively small amounts of milk and when 12 of them were tested with an oral lactose tolerance test the result was a "flat" curve with a maximum rise in blood glucose of 9 plus or minus 3.2 mg/100 ml. The second group consumed more milk averaging 1 quart/day with no discomfort and when 19 were tested with oral lactose tolerance tests the values were normal. This study indicates that low lactase activity in the Caucasian population may make its appearance at the age of 5 years.

Effect of Mild Malnutrition on Disaccharidase Activity and Glucose Uptake in Intestinal Brush Border Vesicles of Growing Monkeys

“…In contrast, McMichael(l5) showed that in patients with normal lactase activity there was no correlation between lactase activity and maximum blood glucose increase after an oral load of lactose. However, several other studies have shown a positive correlation between LTT and lactase activity in the human small intestine (16,17). The partial villus atrophy observed (18) is in accordance with these biochemical findings.…”

Lactose Intolerance in Children with IgE-Dependent Allergy to Milk Proteins

“…All examined patients below the age of 5 showed normal activity of lactase, whereas in those more than the age of 5, decreased lactase activity was observed in 24.6% of patients. 19 There are available data confirming the effect of malnutrition on a lowered activity of lactase. [20][21][22][23] The authors have linked this abnormality to insufficiency in protein as the substrate for the production of enzymes.…”

Intolerância à lactose: mudança de paradigmas com a biologia molecular

“…Nos ratos e coelhos, a lactase não é detectada até alguns dias antes do nascimento, aumentando na fase tardia da gestação com pico logo após o nascimento. Já no intestino humano, os níveis de lactase são baixos até a 27ª-32ª semana de gestação, quando se elevam, rapidamente 57 , começando a cair por volta dos cinco anos de idade 58 . Desta forma, os bebês prematuros nascidos com 28 a 32 semanas de gestação têm atividade reduzida de lactase 59 , porém se forem de outra maneira saudáveis, o cólon pode recuperar os carboidratos não absorvidos, prevenindo a desnutrição e diarreia.…”