Effects of xylitol on gastric emptying and food intake

We studied the effects of xylitol, the pentose-sugar alcohol, on gastric emptying of the solid-food component of a complex meal. Gastric emptying was measured in human volunteers by utilizing a standardized radiolabeled scrambled-egg meal. After ingestion of 25 g xylitol, gastric emptying was markedly prolonged (T-1/2 58 +/- 5 min control vs 91 +/- 7 min after xylitol [p less than 0.01]). Since delayed gastric emptying may affect food intake, we evaluated the effects of xylitol on calorie intake. Food intake after oral preloading with water resulted in intake of 920 +/- 60 kcal vs 690 +/- 45 kcal after 25 g of xylitol. In contrast, a preload of glucose, fructose, or sucrose failed to suppress food intake. Although xylitol decreased food intake and also delayed gastric emptying, these effects may be unrelated. Our data suggest a role for xylitol as a potentially important agent in dietary control.     

Metabolic investigations after xylitol infusion in human subjects.

Evidence has been sought for minor degrees of thiamin and pyridoxine deficiency in patients undergoing surgery who have been infused with xylitol as a parenteral nutrient. Some metabolic changes which are associated with this practice have been studied; the findings are compared with those obtained in similar patients infused with glucose solutions. The thiamin status of all of the subjects was normal. Some of the patients showed slight biochemical evidence of pyridoxine deficiency, but there were no untoward effects of xylitol infusion. The concentration of oxalate in the blood and the excretion of oxalate in the urine did not exceed the normal range in any patient. The plasma and urine orthophosphate and urinary pyrophosphate levels decreased in association with the infusion of both xylitol and glucose. Plasma pyrophosphate and calcium levels, and the urinary calcium level, were essentially unaltered. A detailed quantitative study of the urinary organic acid excretion by means of gas chromatography/mass spectrometry showed that there was an abnormal glycolic aciduria and tetronic aciduria associated with xylitol infusion, but not with glucose infusion. There was no evidence of increased oxalate excretion in any patient by this method. The biochemical and clinical significance of these findings is discussed.     

Gastrointestinal tolerance of erythritol and xylitol ingested in a liquid

OBJECTIVES: To determine and compare the gastrointestinal (GI) responses of young adults following consumption of 45 g sucrose, 20, 35 and 50 g xylitol or erythritol given as a single oral, bolus dose in a liquid. DESIGN: The study was a randomized, double-blind, placebo-controlled study. SUBJECTS: Seventy healthy adult volunteers aged 18-24 years were recruited from the student population of the University of Salford. Sixty-four subjects completed the study. INTERVENTIONS: Subjects consumed at home without supervision and in random order, either 45 g sucrose or 20, 35 and 50 g erythritol or xylitol in water on individual test days, while maintaining their normal diet. Test days were separated by 7-day washout periods. Subjects reported the prevalence and magnitude of flatulence, borborygmi, bloating, colic, bowel movements and the passage of faeces of an abnormally watery consistency. RESULTS: Compared with 45 g sucrose, consumption of a single oral, bolus dose of 50 g xylitol in water significantly increased the number of subjects reporting nausea (P<0.01), bloating (P<0.05), borborygmi (P<0.005), colic (P<0.05), watery faeces (P<0.05) and total bowel movement frequency (P<0.01). Also 35 g of xylitol increased significantly bowel movement frequency to pass watery faeces (P<0.05). In contrast, 50 g erythritol only significantly increased the number of subjects reporting nausea (P<0.01) and borborygmi (P<0.05). Lower doses of 20 and 35 g erythritol did not provoke a significant increase in GI symptoms. At all levels of intake, xylitol produced significantly more watery faeces than erythritol: resp. 50 g xylitol vs 35 g erythritol (P<0.001), 50 g xylitol vs 20 g erythritol (P<0.001) and 35 g xylitol vs 20 g erythritol (P<0.05). CONCLUSIONS: When consumed in water, 35 and 50 g xylitol was associated with significant intestinal symptom scores and watery faeces, compared to the sucrose control, whereas at all levels studied erythritol scored significantly less symptoms. Consumption of 20 and 35 g erythritol by healthy volunteers, in a liquid, is tolerated well, without any symptoms. At the highest level of erythritol intake (50 g), only a significant increase in borborygmi and nausea was observed, whereas xylitol intake at this level induced a significant increase in watery faeces.     

Effect of peroral administration of xylitol on exocrine secretions of monkeys.

The effects of the administration of xylitol on the biochemical properties of monkey parotid and submandibular saliva and lacrimal fluid were investigated. Monkeys (Macaca mulatta) were fed either a sucrose or xylitol diet for 3 days. Ingestion of xylitol was associated with a significant increase of the activity of the salivary lactoperoxidase. The concentration of protein was also increased. Higher lactoperoxidase activity was found in parotid than in submandibular saliva. The concentrations of inorganic phosphate, calcium and SCN ions were practically unaffected. The concentration of SCN ions in pilocarpine stimulated monkey saliva was low (less than 5.5 mg/liter). Peroral administration of 2.5 g of xylitol or sorbitol per day to M. fascicularis resulted in almost similar levels of salivary lactoperoxidase activity. The administration of xylitol orally or by gastric intubation was not found to affect the concentration of lactoperoxidase, protein, phosphate, and SCN and iodine ions in lacrimal fluid. The results suggest that specific dietary sugars have a selective effect on the biochemical properties of saliva.     

Effects of xylitol as a sugar substitute on diabetes-related parameters in nondiabetic rats

Abstract The present study was examined the effects of xylitol feeding on diabetes-associated parameters in nondiabetic rats. Seven-week-old male Sprague-Dawley rats were randomly divided into three groups: control (five rats), sucrose (six rats), and xylitol (six rats). Animal had free access to a commercial rat pellet diet, and ad libitum water, 10% sucrose solution, and 10% xylitol solution were supplied to the control, sucrose, and xylitol groups, respectively. After 3 weeks of feeding of experimental diets, food intakes were significantly (P<.05) lower in the sucrose and xylitol groups compared with the control group. Drink intake was significantly higher in the sucrose group but significantly lower in the xylitol group compared with the control group. Body weight gain was significantly lower in the xylitol group compared with the sucrose group. Weekly nonfasting blood glucose was significantly increased, but fasting blood glucose was significantly decreased, in the sucrose group compared with the control and xylitol groups. Significantly better glucose tolerance was observed in the xylitol group compared with the control and sucrose groups. Serum insulin and fructosamine concentrations were not significantly influenced by the feeding of xylitol or sucrose. Relative liver weight and liver glycogen were significantly increased in the xylitol group compared with the sucrose group, whereas no difference was observed between the xylitol and control groups. Serum total cholesterol and low-density lipoprotein-cholesterol were significantly decreased in the sucrose and xylitol groups, and serum triglyceride of the xylitol group, but not the sucrose group, was significantly increased compared with the control group. Data of this study suggest that xylitol can be a better sweetener than sucrose to maintain diabetes-related parameters at a physiologically safer and stable condition.     

Effects of xylitol versus glucose on urea synthesis and alanine metabolism in rats

The relation between xylitol concentration (1.0 and 5.5 mmol/1), the Capacity of Urea-N Synthesis, and the rate of Alanine Metabolism was investigated in nephrectomized rats of 200 g and compared with the effect of glucose at concentrations between 5.5 and 15.5 mmol/1. The xylitol and glucose concentrations were controlled by "clamp" techniques and the endogenous hormonal effects by somatostatin. The Capacity of Urea-N Synthesis was determined during alanine infusion to constant amino acid concentrations within the interval 7.3-11.6 mmol/1. The rate of alanine metabolism was assessed as alanine infusion rate corrected for changes in alanine concentration. At normal hormonal response, xylitol at 1.0 mmol/1 and 5.5 mmol/1 reduced urea synthesis from 10.3 +/- 1.1 mumol/(min.100 g) in controls to on average 6.2 +/- 0.9 mumol/(min.100 g) (mean +/- SD, n = 2 x 10, p < 1.01). Alanine metabolism was reduced to the same extent. Glucose concentration increased from 5.4 +/- 1.0 mmol/1 in controls to 8.1 +/- 1.4 mmol/1 at both xylitol concentrations. Xylitol reduced plasma glucagon concentration to one third and tripled plasma insulin concentration. During somatostatin and blood glucose maintained above 8 mmol/1, the Capacity of Urea-N Synthesis fell to 6.1 +/- 1.0 mumol/(min.100 g). In that situation, xylitol at 1.0 mmol/1 reduced neither urea synthesis nor alanine metabolism, whereas xylitol at 5.5 mmol/1 further reduced urea synthesis to 3.4 +/- mumol/(min.100 g) (n = 10, p < 0.05) and almost stopped alanine metabolism. Thus xylitol, independently of glucose and hormonal responses, inhibited urea synthesis and alanine metabolism. This may have therapeutic implications at catabolic conditions.     

Metabolic effects in rats of high oral doses of galactitol, mannitol and xylitol

The effect of feeding high amounts of polyols on rat metabolism was studied. Adult male rats were fed the basal diet or the same diet to which had been added either galactitol, mannitol or xylitol for 8 wk (final polyol level 200 g/kg diet). Although all three polyols retarded the growth rate of the animals, the polyols were well tolerated. The four experimental groups did not differ significantly (P greater than 0.01) in the following analyses: blood lactic acid and serum transaminases, amylase, lactate dehydrogenase, triglycerides, insulin, glucagon and corticosterone. Compared to rats fed the basal diet, galactitol rats had higher blood hemoglobin levels (P less than 0.01); those fed galactitol or mannitol had lower blood glucose (P less than 0.001 and P less than 0.01, respectively), and those fed mannitol had higher blood pyruvic acid (P less than 0.01). Rats fed any of the polyols had lower serum total cholesterol and liver ascorbic acid (P less than 0.001) than control rats. Rats fed mannitol had higher liver glycogen levels (P less than 0.001) than control rats. Irrespective of the structural differences between the pentitol and the hexitols, a number of common metabolic effects were found. The proposed mechanisms of these effects include 1) the slow absorption and the rapid intraluminal metabolism of the polyols and 2) the similar handling of these polyols in the liver by a dehydrogenase.     

Effect of excess xylitol on nitrogen and glucose metabolism in parenterally fed rats.

The objectives of this study were to investigate the effects of an excess of xylitol on nitrogen balance and glucose metabolism in parenterally fed rats. Female Sprague-Dawley rats (200-250 g, n = 17) were catheterized for total parenteral nutrition and then randomized into two groups based on subsequent diet. The two diets used were isonitrogenous (1.5 g of nitrogen per kilogram per day) and isocaloric, with half the calories (125 kcal/kg per day) being derived from lipid (125 kcal/kg per day) and the other half from either glucose or xylitol (125 kcal/kg per day). The rats were fed a half-strength total parenteral nutrition diet for the day after surgery and a full-strength total parenteral nutrition diet for the following 4 days. Urines were collected daily for the determination of nitrogen balance. On day 5, the rats were given a 7- to 8-hour infusion of 6.6-d2 glucose (6 mg/h and 2-d1 glucose (12 mg/h). At the conclusion of the isotope infusion period, the rats were killed and blood was collected. Urine output was increased by 22% per day in the xylitol-treated rats, and they excreted 46.5 mmol of xylitol per liter per kilogram per day (7.1 g/kg per day, approximately 22.7% of dose). The xylitol group lost weight, had poorer nitrogen balance (341 +/- 31 vs 83 +/- 29 mg/kg per day [mean +/- standard error of the mean], p < .05), and developed fatty livers. Analysis of the liver fat distribution pattern indicated that the source of the excess hepatic lipid was dietary fat.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exocrine gland enzyme levels after peroral administration of xylitol and sorbitol in the rat

Rats were given xylitol or sorbitol perorally during a 150-day period in drinking water. The polyols were given in equimolar concentrations and their average daily consumption was 2.0 g per kg body weight. At the end of the feeding schedule the submandibular, parotid and lacrimal glands of the animals were studied for the levels of peroxidase, alpha-amylase, proteases and protein. The sorbitol-fed rats had lower body weights compared with the xylitol-fed siblings, but the differences were not significant. The same concerned the fresh weights of the glands studied. The levels of the enzymes and protein determined did not differ significantly between the feeding groups. The results provided further support to the idea that sorbitol and xylitol may not differ with regard to their effects on the peroxidase, amylase and proteinase levels of the three exocrine glands studied in rats, and that the xylitol-associated increase of the lactoperoxidase levels, previously observed with saliva, may confine to primates only.     

The comparative oxidation of glucose, fructose, sorbitol and xylitol in normal man

The aim of the study was to compare the effects of fructose, sorbitol and xylitol with those of glucose on blood glucose and insulin levels and carbohydrate utilization in man. The experiment was performed by means of continuous indirect calorimetry in five groups of five to six normal volunteers during infusion of either glucose, fructose, sorbitol, xylitol or a mixture of fructose, glucose and xylitol in the proportion of 2:1:1. Glucose and insulin did not present any important variations during the fructose, sorbitol and xylitol infusiosns. However, carbohydrate oxidation rose significantly during administration of these substrates. Carbohydrate oxidation rose 80 mg/min for fructose, 27 mg/min for sorbitol, 39 mg/min for xylitol and 75 mg/min for the carbohydrate mixture, in comparison to 101 mg/min for glucose. It is concluded that fructose, sorbitol and xylitol provoke an increase in carbohydrate utilization without a corresponding rise in glycemia and insulinemia.     

Effect of peroral xylitol on the concentration levels of lipids and electrolytes in rat tissues

The effect of glucose (G) and xylitol (X) feeding on the fat and electrolyte metabolism was studied with 24 adult male rats divided into three groups of 8 for a 30-day experiment. One group was fed the stock diet supplemented with X (3000 mg/kg body wt./day); the second group the same diet supplemented with G (3000 mg/kg body wt./day), and the third the stock diet without added carbohydrates. During the last 24-hr period of the feeding schedule the animals were given ¹⁴C(U)-labeled G or X. Samples of serum, liver, kidneys, pancreas, spleen, duodenum wall, parotid glands, and the entire submandibular and lacrimal glands were analyzed for neutral lipids, phospholipids, Na, K, Mg, Ca, Fe, Cl^? and inorganic phosphorus. The X-fed animals showed smaller weight gains and their lacrimal and submandibular glands were significantly smaller than in other feeding groups. The weights of kidneys, however, did not differ significantly. At least in the case of submandibular glands, the reduced gland weights were associated with decreased levels of tissue K, Ca, Mg, inorganic phosphorus and Cl^?. Several organs of the G-fed animals displayed reduced Na contents. X-fed rats showed elevated concentrations of Fe in livers, kidneys and spleen, increased labeling of serum neutral lipids, and increased concentrations of triglycerides (TG) and free fatty acids (FFA) in lacrimal and submandibular glands. The G-fed animals showed decreased concentrations of serum lysolecithin, but elevated levels of TG in serum and the lacrimal and submandibular glands. X feeding increased serum lysolecithin compared to G feeding. These results suggest that physiological, peroral X administration increases the rate of lipolysis, facilitates the absorption of iron and exerts specific effects on exocrine gland function in rats. Most findings in the X group were significant only when compared to the G group. Minor differences existed when X-fed rats were compared to control rats. Since high carbohydrate diets usually result in reduced plasma FFA and increased plasma TG, the higher FFA and lower TG in the X-fed rats compared to the G-fed group, therefore, represented a lack of high G effects.     

A review on different modes and methods for yielding a pentose sugar: xylitol

Xylitol, a five-carbon polyalcohol, holds a substantial place in the cure and prevention of a number of diseases. The foremost reason for its lesser usage in day-to-day practice is its cost. The method employed on large scale production of this polyol, i.e. chemical reduction, uses extensive machinery and expensive chemicals thus increasing the basic cost of the sugar. Yield of xylitol by other methods including fermentation and enzymatic production is far less than chemical reduction. We did a literature analysis and briefed out the various experiments carried out till date and concluded on the required studies for improving its production and lowering down its cost.     

Effect of total parenteral nutrition with xylitol on protein and energy metabolism in thermally injured rats

The use of xylitol as an alternative carbohydrate calorie source in total parenteral nutrition may offer unique pharmacologic and nutritional properties in the therapy of the thermally injured. Male Sprague-Dawley rats (250 g) received a 15-second dorsal scald injury (25-30% BSA) and were parenterally fed isovolemic diets (60 ml/day) that provided 200 kcal/kg/d, 9.68 g of amino acids/kg/d, and 23.5% nonprotein calories (NPC) as fat for 3 days. The balance of NPC were provided as dextrose (Dex) or 50% xylitol:50% dextrose (Xyl/Dex). Rectus muscle and liver fractional protein synthetic rates (FSR, %/day), whole body leucine appearance (Flux), oxidation (OX), protein breakdown (PB), and synthesis (PS) were estimated using a 4-hour iv infusion of [1-14C]leucine on day 3. Mean values (+/- SE) for leucine kinetics (mumol leucine/hr/100 g), cumulative nitrogen balance (mg N) and plasma insulin concentration (Table I). (microU/mL). The partial replacement of dextrose calories with xylitol did not significantly alter whole body and tissue leucine kinetics, daily and cumulative nitrogen balance, insulin concentration, and energy expenditure (indirect calorimetry). These data indicate that xylitol may be useful as an alternative carbohydrate calorie source in parenteral nutrition to avoid possible deleterious side effects of glucose overfeeding in the critically ill but did not improve protein metabolism under the conditions of this study.     

Threshold for transitory diarrhea induced by ingestion of xylitol and lactitol in young male and female adults

The ingestion of a sufficiently large amount of non-digestible and/or non-absorbable sugar substitutes causes overt diarrhea. The objective is to estimate the non-effective dosage that does not cause transitory diarrhea for xylitol, lactitol, and erythritol in healthy subjects. Twenty-seven males and 28 females gave informed and written consent to participate, were selected, and participated in the study. The oral dose levels of xylitol were 10, 20, 30, 40 and 50 g, while those of lactitol were 10, 20, 30, and 40 g. Those of erythritol were 20, 30, 40 and 50 g. The test substance was ingested in 150 mL of water 2-3 h after a meal. The ingestion order progressed from the smallest to larger amounts, and stopped at the dose that caused diarrhea, or at the largest dose level to be set up. The non-effective dose level of xylitol was 0.37 g/kg B.W. for males and 0.42 g/kg B.W. for females. That of lactitol was 0.25 g/kg B.W. for males and 0.34 g/kg B.W. for females, and that of erythritol was 0.46 g/kg B.W. for males and 0.68 g/kg B.W. for females. These results appear reasonable, because xylitol is poorly absorbed from the small intestine, and the absorption rate is less than that of erythritol, while lactitol is not hydrolyzed. Non-digestible and/or non-absorbable sugar alcohols and oligosaccharides with beneficial health effects inevitably cause overt diarrhea. The estimation of the non-effective dose level of these sugar substitutes is essential and important to produce processed foods that the consumer can use safely and with confidence.