Trehalase deficiency. Prevalence and relation to single-cell protein food.

Perspectives in nutrition suggest a greater use of single-cell proteins in the future. The problems of a high purine content and of potential allergens have been solved by technology. The single-cell proteins may contain trehalose, the absorption of which by the human intestine necessitates prior hydrolysis by trehalase, a specific brush-border disaccharidase. The enzymatic analysis of 100 intestinal biopsies discovered 2 cases of very low trehalase level, with an expected clinical intolerance to even small doses of trehalose. It is concluded that tolerance to high doses of trehalose should be excellent in about 98% of healthy people.

[Diagnosis of lactase deficiency with the expired hydrogen (H2) test]. / Diagnostic des déficits en lactase par le test de l'hydrogène (H2) expiré.

To determine the sensitivity and specificity of breath hydrogen (H2) in detecting lactase deficiency, breath H2 collected by end-expiratory sampling and capillary blood glucose were measured after ingestion of 50 g of lactose in 36 patients with biopsy-proved isolated lactase deficiency, 42 with normal lactase activity and 6 with lactase deficiency secondary to mucosal lesions. All patients had digestive symptoms clinically compatible with lactose malabsorption. The maximum increase in breath H2 concentration was more than 1.1 mumol/l (25 ppm) in all patients with isolated lactase deficiency, and less than 0.88 mumol/l (20 ppm) in 88% of patients with normal lactase activity; there were 5 false-positive results, attributed in one case to small bowel colonization and in another case to rapid transit after gastric surgery. Secondary lactase deficiency was accurately detected by neither breath H2 nor blood glucose.

Significance of duodenal disaccharidases. A comparative study of duodenal and jejunal values.

Endoscopic biopsies at the inferior duodenal flexure from 36 patients were assayed for disaccharidases. Comparative studies in 8 patients were carried out from this location and from the duodenojejunal flexure. 16 patients with lactase values under 20 U/g protein and normal histology also underwent a lactose tolerance test. Evidence is presented that the easily performed duodenal biopsies give the same information as those from the angle of Treitz, at a level about 40% under the latter. Tolerance to lactose was in close relation with the lactase level in 16 patients, the limit being at about 5 U/g protein.

[Exhaled hydrogen test in the detection of lactase deficiency]. / Test de l'hydrogène expiré dans la détection des hypolactasies.

To determine the validity of breath H2 measurements in detecting lactase deficiency, capillary blood glucose and breath H2 were measured after ingestion of 50 g lactose in 34 patients with abdominal symptoms or diarrhea. 18 patients had biopsy-proven lactase deficiency and 16 normal lactase activity. Blood glucose determination produced 2 false-positive results while breath H2 measurements provided 2 false-negative and 4 false-positive results.