Some factors influencing absorption rates of the digestion products of protein and carbohydrate from the proximal jejunum of man and their possible nutritional implications

Jejunal absorption rates of glucose and glycine in post-infective tropical malabsorption

In a prospective study jejunal absorption rates of glucose (from a 200 mmol 1-1 solution) and glycine (from a 100 mmol 1-1 solution) were measured, using a perfusion technique, in nine patients with clinical evidence of post-infective tropical malabsorption (TM group) and in 10 others with trivial symptoms who had also visited the tropics (control group); all were of northern European origin. Seven and one in the two groups, respectively, had Giardia lamblia infections. Mean glucose absorption rate was significantly impaired by TM (P less than 0.01); mean rate for glycine was also depressed but not significantly. Presence of G. lamblia did not affect the severity of malabsorption although numbers studied were small.

Parasites ana malabsorption

Intestinal parasites not only cause diarrheal illnesses but may also cause significant malabsorption in man. Separation of true malabsorption caused by a particular parasite from other factors that may coexist with and even mimic malabsorption, such as malnutrition may be very difficult. Despite these problems, it appears that giardiasis, coccidiasis, strongyloidiasis and capillariasis cause malabsorption of many important nutrients. D. latum interfere with vitamin B12 absorption.

Rapid glucose absorption in Arabs in Saudi Arbia compared with that in Africans in Zambia

Glucose absorption rates in 14 Arabs in Saudi Arabia were determined by a jejunal perfusion technique and compared with those in 18 Africans in Zambia. None of the subjects had clinical evidence of systemic infection, gastrointestinal disease, malnutrition, or diabetes mellitus. The mean absorption rate was significantly higher in the Arabs. This was associated with a higher incidence of subclinical chronic systemic infection in the Africans. Other factors possibly responsible for the difference, including genetic difference, have, however, not been excluded.

The short-term response to a drink of milk, lactose or casein in children with apparently normal gastrointestinal tracts

1. Drinks of milk, lactose and casein were given to children who, though suspected of having malabsorption, were subsequently found to have normal gastrointestinal tracts. The plasma concentrations of glucose, amino acids, urea and insulin following these drinks were measured. The results can probably be taken to represent control values when investigating children with gastrointestinal or metabolic disorders.

2. The rise in plasma amino acids after giving casein and the rise in plasma glucose after giving lactose were greater than those after giving equivalent amounts of milk.

3. The absorption of an individual food constituent and its uptake by the tissues are influenced by the presence of other food constituents so that ‘tolerance tests’ with individual nutrients may not be truly physiological.

Reaction of human small intestine to an intraluminal tube and its importance in jejunal perfusion studies

A double-lumen tube with a mercury weight attached to its distal end was positioned in the small intestine of six subjects who were to undergo an elective laparotomy. The tube and the technique for its localization were exactly similar to those used in previous intestinal perfusion experiments. Marked ;concertinaing', or gathering of the small intestine proximal to the mercury weight, was seen at laparotomy in all six subjects. The ratio between the mean intestinal length from the mercury weight to the ligament of Treitz after removal of the tube to that with the tube in situ was 3.0 (2.5-3.8). Mean total jejuno-ileal length was 421 (320-521) cm. In five of the six subjects the distal end of the tube was more than half way between the ligament of Treitz and the ileo-caecal valve although it was only 100-120 (mean 108) cm from the incisor teeth. Segmental perfusion studies of the human jejunum involve a much longer length of small intestine than is generally assumed-by a factor of approximately 3. Such studies assess absorption rates over a substantial proportion of the small intestine and are not confined to a short segment of proximal jejunum. The nutritional significance of such studies in which amino acids, peptides, and carbohydrates are investigated is increased. Studies designed to measure absorption rates from the ileum should be treated with caution as part or all of the perfusion segment may be past the ileo-caecal valve.