(Gut 1997; 41: 70-76)

No abstract

Studies attempting to evaluate protein assimilation in humans have hitherto relied on either ileostomy subjects or intubation techniques. The availability of stable isotope-labeled protein allowed us to determine the amount and fate of dietary protein escaping digestion and absorption in the small intestine of healthy volunteers using noninvasive tracer techniques. Ten healthy volunteers were studied once after ingestion of a cooked test meal, consisting of 25 g of (13)C-, (15)N-, and (2)H-labeled egg protein, and once after ingestion of the same but raw meal. Amounts of 5.73% and 35.10% (P < 0.005) of cooked and raw test meal, respectively, escaped digestion and absorption in the small intestine. A significantly higher percentage of the malabsorbed raw egg protein was recovered in urine as fermentation metabolites. These results 1) confirm that substantial amounts of even easily digestible proteins may escape assimilation in healthy volunteers and 2) further support the hypothesis that the metabolic fate of protein in the colon is affected by the amount of protein made available.

Gastric acid suppression therapy hampers protein assimilation and may promote protein malabsorption. Gastric digestion is likely to play a substantial role in overall protein assimilation.

Thirty-six infants and children presenting with recurrent respiratory disorders (RRD) as the sole clinical symptom including bronchial asthma (6), recurrent obstructive bronchitis with or without wheezing (18), chronic nocturnal cough (3), recurrent episodes of pneumonia (3), recurrent pharyngitis (3) and recurrent laryngitis (3) were investigated for associated gastro-oesophageal reflux (GER) by oesophagram, endoscopy and continuous 24 h pH monitoring of the distal oesophagus. The pH monitoring criteria were selected on the basis of a preliminary study comparing statistically measurements of 32 variables recorded in 15 patients who all had clinical, radiological and endoscopic evidence of GER and in 8 asymptomatic controls. Although patients with symptomatic GER differed significantly from the asymptomatic ones for 27 variables examined, 6 variables emerged as having the highest value for discrimination (overlap score 0-1). Among these, the Euler-Byrne index (number of reflux pH less than 4 + 4 times the number of reflux episodes of more than 5 min), the percentage of total reflux time and the number of reflux episodes 1 h post-cibal scored 0 (no overlap). GER was considered to be present when at least five of these six parameters were abnormal. The overall incidence of GER in children with RRD was 41% (15) when detected by oesophagram and 61% (22) when diagnosed by pH monitoring criteria. In the children with bronchial asthma or with recurrent laryngitis, the percentage of reflux time during sleep was about 40 times higher than in asymptomatic controls and 2 times higher than in those with symptomatic GER.(ABSTRACT TRUNCATED AT 250 WORDS)