No abstract

The caecal microflora of Cara rats was incubated in the pH stat with glucose under anaerobic conditions, and the acid production was measured. In the presence of the sweeteners Acesulfame K, Cyclamate and Saccharin, inhibition of the fermentation of glucose was observed with ED50 values of 260, 251, and 140 mM, respectively. The nutritional relevance of these observations is probably slight; an interpretation in terms of bacterial physiology leads to the proposal that the sweeteners may act on glucose transport systems at the bacterial cytomembrane.

1. Breath hydrogen and methane were determined by gas chromatography in eleven normal individuals given a low-fibre, mixed diet (control) and after ingestion of 20-50 g Palatinit@/d, an equimolar mixture of Dglucosyl-a( I + l)-D-mannitol and D-glUCOSyl-a( 1 + 6)-~-glucitol (Isomalt@).2. A linear relation was found (r 0.85; P < 0.001) between the amount of Palatinit ingested and breath H, per 10 h in subjects who did not exhale methane. If methane was formed in addition to H,, the sum of both gases followed a linear dose-effect relation.3. The mouth-to-caecum time, indicated by the first increase in breath H, after ingestion, was shortened by about half, yet no sign of diarrhoea was observed. Stool weight and stool frequency did not change significantly. The linear relation between a dose of 20-50 g Palatinit and exhalation of H, (eventually plus methane)indicated that a relatively constant fraction of the dose given underwent cleavage and absorption in the small intestine, the remainder being transported into the large bowel. Microbial gas formation in the colon as well as the fractional transfer of these gases into the expiratory air occurred at fixed proportions, thus allowing an insight into colonic microbial contributions to carbohydrate utilization in the human large bowel.

Hydrogenated palatinose, an equimolar mixture of alpha-D-glucopyranosido-1,6-sorbitol and alpha-D-glucopyranosido-1,6-mannitol, was investigated as a potential oral sugar substitute in the following experiments in man and rat. 1. Enzymatic cleavage occurred at slow rates by maltase (alpha-glucosidase) of jejunal mucosa, liver lysosomes and yeast. 2. Part of ingested hydrogenated palatinose arrived unsplit at the caecum of the rat and underwent fermentation there; excretion in feces and urine are neglegible in man and rat. 3. Growth and maintenance of rats demonstrated 20--40 percent diminished caloric utilisation of diets containing 34.5 percent hydrogenated palatinose whereas indirect calorimetry in man showed about 50 percent caloric deficit. 4. Blood sugar did not increase in man after oral doses up to 100 g. 5. The capacity of the rat kidneys for excretion of hydrogenated palatinose and its constituents was high, symptoms of incompatibility were not observed.

Leucrose [D-glucosyl-α(1→5)-D-fructopyranose] prepared by microbial-enzymatic transglycosidation from sucrose, is the first α(1→5)-linked disaccharide which possesses excellent nutritional properties with regard to metabolic utilization and is well tolerated. The aim of the present work was to assess its cariogenic potential. Yeast invertase was shown to be inhibited by leucrose in a noncompetitive way, while hydrogenated leucrose (leucritol) acted as an activator. Plaque polysaccharide forming glucosyltransferases from Streptococcus cricetus AHT were not influenced by leucrose, but by leucritol. Essentially no acid formation was observed after incubation of leucrose with suspensions of human dental plaque, S. mutans NCTC 10449, Lactobacillus casei LSB 132 and Actinomyces viscosus Ny 1 No. 30. Leucrose was a competitive inhibitor of the acid formation from sucrose by S. mutans NCTC 10449 at neutral pH. Furthermore, leucrose inhibited at neutral pH considerably the uptake of sucrose by S. mutans NCTC 10449. The uptake of fructose and maltose was also inhibited but that of glucose not at all. In Cara rats as the animal model, leucrose was compared to sucrose and to corn starch for its cariogenic potential. In sharp contrast to the group fed with 30% sucrose, caries scores of the 30% leucrose group were not significantly different from the starch group. pH telemetry with an indwelling electrode in man proved leucrose to be ‘safe for teeth’ since plaque pH did not drop below pH 5.7. Leucrose is a novel noncariogenic disaccharide and thus represents a highly promising sugar substitute for caries prevention.