Lactose Malabsorption and Intolerance in the Elderly

M. Di Stefano, G. Veneto, S. Malservisi, A. Strocchi & G. R. Corazza Gastroenterology Unit, IRCCS ―S. Matteo‖ Hospital, University of Pavia, Pavia, Italy.

Di Stefano M, Veneto G, Malservisi S, Strocchi A, Corazza GR. Lactose malabsorption and intolerance

in the elderly. Scand J Gastroenterol 2001;36:1274 –1278.

Background: Lactase activity declines with age in rats, but it is not clear whether this model is also shared by humans. Few studies have evaluated lactose intolerance and malabsorption in the elderly and no definite conclusions can be drawn. The aim of our study was therefore to verify the impact of age on lactose intolerance and malabsorption.

Methods: Eighty-four healthy subjects took part in the study. Thirty-three were <65 years, 17 were between 65 and 74 years and 34 were >74 years. All the subjects underwent a preliminary

evaluation of intestinal gas production capacity and oro-cecal transit time by H2/ CH4 breath test after lactulose. After a 3-day period, an H2/CH4 breath test after lactose was performed . The occurrence of intolerance symptoms during the test and in the 24 h after the test was recorded.

Results: Breath H2 and CH4 excretion parameters at fasting and after lactulose did not differ between the three groups. Cumulative breath H2 excretion after lactose was higher in subjects >74 years than in subjects <65 years and in subjects aged 65–74 years, while no difference was found between the latter two groups. In subjects >74 years, the prevalence of lactose malabsorption was higher than in the other two groups, while no significant difference was observed between subjects <65 years and subjects aged 65–74 years. Within the malabsorber subjects, the prevalence of lactose intolerance was higher in subjects <65 years than in those aged 65–74 years and in those aged >74 years. No significant difference was found between the latter two groups. No difference was found between the three groups in terms of daily calcium intake and a

significant negative correlation between symptom score and daily calcium intake was only found in the group of subjects aged <65 years.

Conclusions: As age increases, the prevalence of lactose

malabsorption shows an increase while the prevalence of intolerance symptoms among malabsorbers shows a decrease . Accordingly, daily calcium intake was similar among the adults and elderly studied.

Key words: Elderly; H2-breath test; intestinal gas production; lactose intolerance; lactose malabsorption; methane production G. R. Corazza, Gastroenterology Unit, IRCCS ―S. Matteo‖ Hospital, Viale Golgi 19, 27100, Pavia, Italy (fax. ?39 0382 502618, e-mail. m.distefano@smatteo.pv.it )

Human adult-type hypolactasia is widespread throughout the world due to a genetically determined decline of lactase activity inherited through an autosomal recessive gene (1). Its prevalence is highly variable, ranging from 5% in north-west Europe to almost 100% in some Asian populations (2). On clinical grounds, hypolactasia is responsible for lactose malabsorption, which may cause symptoms such as abdominal pain, bloating, flatulence and diarrhea, evoked by milk consumption (3).

In human beings, the lactase decline pattern is similar to that

observed in mammals such as rats (4). However, although in rats lactase activity declines further in old age (5–7), it is not very clear whether this model is also shared by humans. The measurement of lactase activity, in fact, gave conflicting results (8, 9) probably

because of the marked effect of small differences in the biopsy site

(10). Only a few studies have evaluated lactose intolerance and malabsorption in the elderly by means of the hydrogen (H2) breath test (11–14), but, again, no definite conclusions could be drawn owing to differences in the methods used and in the ethnic background of the subjects.

Accordingly, the aim of this study was to verify the impact of age on lactose intolerance and malabsorption assessed by the H2 breath test. Unlike previous studies, breath H2 and methane (CH4)

excretion after lactulose administration were first evaluated in all subjects to exclude the possible interference of unrelated factors

such as differences in (a) H2 production capacity (15), (b) small intestine transit time (16), (c) occurrence of bacterial overgrowth

(17) and (d) colonic H2 consumption (18).

Subjects and Methods

Patients

Eighty-four healthy subjects (60

women, 24 men; age range 23–94

years) took part in the study. Thirty-three subjects were <65

years (23 women, 10 men; mean

age 45 +/- 15 years). Seventeen subjects were between 65 and 74 years (12 women, 5 men; mean age 69 +/- 3 years) and 34 subjects were >74 years (25 women, 9 men; mean age 81 +/- 4 years).

Thirty-three subjects (all <65 years) were members of medical or paramedical staff of our hospital, while 51 were members of the ?Third Age University‘, an association organizing cultural and recreational events for elderly people. All were compliant and gave their informed consent to the study. Subjects with intestinal, liver, renal, chest, cardiac, metabolic or neurologic disease or who were taking antibiotics, prokinetics, laxatives or any other drug known to influence colonic flora in the month preceding the study were excluded.

In all subjects nutritional status was assessed by anthropometric criteria. As given in Table I, there was no significant difference

between the three groups of subjects in terms of body mass index, thickness of tricipital skin fold and middle arm circumference.

Daily calcium intake was assessed in each subject by completing a dietary diary for three non-consecutive days (two non-consecutive weekdays and one weekend day) listing all the food eaten and the respective quantities, evaluated on the basis of usual portion sizes

(19). The diaries were then checked by one of the authors, who was unaware of the clinical details of the subjects and analyzed on the basis of food-composition tables provided by the Italian National Institute of Nutrition (20). Moreover, each subject was asked whether milk and dairy product consumption led to appreciable abdominal symptoms.

Breath testing

In order to avoid prolonged intestinal gas production, because of the presence of non-absorbable or slowly fermentable material in the colonic lumen, the breath test was preceded by a preparation procedure based on the consumption, the evening before the test day, of a meal consisting of only rice, meat and olive oil (21). This meal was then followed by a 12-h fasting period. Breath testing

started between 0830 h and 0930 h, after thorough mouth washing with 40 mL of 1% chlorhexidine solution. Smoking and physical exercise were not allowed for 1 h prior to and throughout the test.

Sampling of alveolar air was performed by means of a commercial device (Gasampler Quintron, Milwaukee, Wis., USA), which allows the first 500 mL of dead space air to be separated and discarded while the remaining 700 mL of end-alveolar air are collected in a gas-tight bag. Subjects were instructed to avoid deep inspiration and not to hyperventilate before exhalation. A gas chromatograph dedicated to the detection of H2 and CH4 in air samples was used for breath samples analysis (Model DP12, Quintron Instrument, Milwaukee, Wis., USA). The accuracy of the detector was +/- 2 ppm with a linear response range between 2 and 150 ppm of H2 and between 2 and 50 ppm of CH4.

All the subjects underwent a preliminary evaluation of intestinal gas production capacity and oro-cecal transit time by H2 breath test after the ingestion of 400 mL of an iso-osmotic solution containing 20 g of lactulose, a nonabsorbable disaccharide, which is fermented by colonic flora. Breath samples were taken at fasting and every 10 min for a 4- h period. Subjects were considered low H2 excretors if no breath sample contained an H2 concentration exceeding 20 ppm (15) and the test was considered a false-negative if an increase of