Malabsorption and Malnutrition in the Elderly - An Evolution?

Abstract

Purpose: 80% of the elderly population presenting for hospital admission are either malnourished or potentially malnourished. In a similar cohort, potential malabsorption was identified using a Lactulose/Rhamnose study of small intestinal permeability. Increased permeability was present in 21%. When potential malabsorption begins has not been identified and we proposed to study (over 2 years) a group independently living to determine at what age this process begins. Methods: 154 active, independent living elderly were nutritionally assessed at 3 monthly intervals using the Nestle Mini Nutritional Assessment (MNA) and anthropometrics (hand grip, mid-arm muscle circumference (MAMC), tricep skin-fold thickness, body mass index (BMI), calf circumference). Carbohydrate absorption was measured at 6 monthly intervals with a Rice Breath Hydrogen Test (RBHT) to identify small intestinal bacterial overgrowth (SIBO) and carbohydrate (CHO) malabsorption. The test utilized 100 g of rice, hydrogen levels were measured at 20min intervals for 1 hour, then at 30min intervals for a further hour. A lactulose/rhamnose study of small intestine permeability was completed. Baseline blood tests identify any nutritional deficiencies or coeliac disease. Results: Average age was 80.8 years (60-90 years), ratio 3:1 females to males. At baseline 34.2% had abnormal RBHT's, 22.2% showing evidence of CHO Malabsorption (a RBHT with an increase more than 20 ppm). 12% showed evidence of SIBO (a RBHT with a basal level above 20 ppm). Nutritional assessment revealed 25.1% were malnourished or at risk at baseline which increased to 33.3% at 6 months. Calculated from 12 months data, mean MAMC for subjects with a normal RBHT was 25.7 cm, and 25.4 cm for subjects with an abnormal RBHT. At baseline the mean BMI for the normal RBHT group was 26.9, compared to 26.2 in the abnormal RBHT group. At 6 months the mean BMI for the normal RBHT group was 26.9, whereas the abnormal RBHT group mean BMI was 26.8. At 12 months the mean BMI had declined in both groups, normal RBHT group BMI was 26.3, and abnormal RBHT group BMI was 26.2. Blood tests and urine permeability tests have shown no abnormal results. Conclusion: Evaluations are not sufficient to identify onset of malnutrition. The data suggests that CHO malabsorption and SIBO is present in our independent living elderly with changes in nutritional status shown by MNA, BMI and MAMC. The sequence of events suggests SIBO is perhaps the first marker of potential malabsorption followed by rice CHO malabsorption. There has been no significant disturbance of mucosal permeability. We need to identify individual aspects in the genesis of this process - poor small intestinal motility followed by SIBO.