[Vitamins for the eyes? Risks and opportunities for physician and patient]. / Vitamine für das Auge? Risiken und Chancen für Arzt und Patienten.

This article discusses the effects of dietetic measures and specialized food supplements on age-related macular degeneration (AMD) and diabetic retinopathy. The sale of products in doctors' offices is already prohibited by laws governing the medical profession. The results of the Age-Related Eye Disease Study (AREDS) concerning high doses of vitamins and zinc cannot simply be transferred to other doses and substances. Furthermore, there are health risks that have to be examined. Opportunities could arise for both doctor and patient if the AREDS formulation were granted authorization to be marketed as a medicinal product; however, a certain protective effect can be expected only for specific forms of AMD after a careful risk-benefit analysis and assessment within the statutory marketing authorization procedure for medicinal products.

[Vitamins and minerals in food supplements. Up-to-date risk assessment]. / Vitamine und Mineralstoffe in Nahrungsergänzungsmitteln. Eine aktuelle Risikobewertung.

The Federal Institute of Risk Assessment (BfR) has applied principles of scientific risk assessment to derive proposals for maximum levels of vitamins and minerals including trace elements in food supplements and fortified food products. This review describes the special features pertaining to the risk assessment of these essential micronutrients and the procedure used for the derivation of maximum levels for individual food supplements. The applied procedure takes into account tolerable upper intake levels (UL), intakes of vitamins and minerals in normal daily diets and dietary reference values for the derivation of maximum levels in individual food products. In this context, consideration must be given to the possibility of multiple exposure via daily intakes of several food supplements or several fortified food products. A careful risk-benefit analysis was necessary because, with nutrients having a narrow margin of safety, the need to compensate for possibly inadequate intakes or increased demands had to be weighed against the risk of excessive intakes. With nutrients where no UL could be derived due to inadequate databases, the BfR recommends that maximum levels should be set on the basis of nutritional-physiological aspects. It should be noted that this recommendation is based on reasons of preventive health protection.

Representative data of iodine intake and urinary excretion in Germany.

To evaluate the iodine supply of the German population, 2500 representative subjects older than 13 years were elected for answering a specific food questionnaire. In addition spot urine samples in 3 selected risk groups for iodine deficiency (574 adults aged 50-70 years, 769 conscripts, 886 pairs of mothers and newborns) from 26 representative regions were collected. Furthermore the circadian iodine excretion was measured in 24 h urine samples collected in 6 fractions per day in 4 subgroups (young and older males and females) of 91 controls and this 24 h iodine excretion related to iodine/creatinine ratio in these subgroups. Mean estimated iodine intake was 119 microg/d in adults aged 50-70 years, 137 microg/d in conscripts, and 162 microg/d in mothers at still birth. The mean iodine concentration (iodine/creatinine ratio) was 9.4 microg/dl in 566 adults aged 50-70 years, 8.3 microg/dl in 772 conscripts and 5.6 microg/dl in 739 breast fed newborns. The mean daily iodine excretion was 134 microg/d in 278 men aged 50-70 years, 117 microg/d in 288 women aged 50-70 years, 125 microg/d in 772 conscripts and 74 microg/d in 53 breast-feeding mothers not using iodine tablets. These results show, that iodine intake in Germany has increased over the last years. The deficit in iodine intake with significant regional differences and defined risk groups for iodine deficiency (e.g. breast feeding mothers without iodine deficiency prophylaxis) is estimated to be about 30% of the recommended iodine intake.

Lactitol tolerance in healthy Thai adults.

The hydrogen breath analysis test was performed in healthy Thai adults to determine lactitol tolerance. The study was conducted in 39 individuals (11 males and 28 females) aged 18-41 years. All volunteers agreed to participate in this study after the risks and benefits had been fully explained. Subjects were requested not to consume milk, milk products, or high-vegetable diets for a day and to fast from 10 p.m. of the day preceding the test day. After consumption of the test diet (12 and 20 g of lactose or lactitol, respectively, in 250 mL water), the subjects recorded the severity of symptoms for 24 hours. Breath samples were collected after fasting and after consumption of the test diet at 30 min intervals over the 7-hour study period. Breath samples were analyzed for hydrogen using gas chromatography. After consumption of 12 g lactose, the prevalence of lactose malabsorbers was established. The increment of a peak breath hydrogen level of > or = 20 ppm above the baseline level was used as an indicator of lactose malabsorption. The lactose malabsorbers were further classified as lactose tolerance or lactose intolerance according to the gastrointestinal symptoms observed. All 39 healthy Thai adults could be classified into 3 groups as follows: 9 (23%) lactose absorbers (LA), 15 (38.5%) lactose mal-absorber/tolerance (LMT), and 15 (38.5%) lactose mal-absorber/intolerance (LMI). Using the hydrogen breath test, 67% of the subjects were identified as lactitol intolerance after the consumption of 12 g lactitol. The lactitol intolerance comprised 53.8% of LMI, 34.6% of LMT, and 11.5% of LA. Among all subjects, one third of LA (33%), two thirds of LMT (60%), and 93% of LMI were lactitol intolerant. In addition, gastrointestinal symptoms such as flatulence and abdominal pain were most pronounced in LMI. Diarrhea was also a prominent manifestation after consumption of 12 g lactitol. Therefore, it was finally decided that 20 g lactose or lactitol were not given to LMI because of the risk of gastrointestinal symptoms. After high doses (20 g) of lactose and lactitol consumption, most LMT developed more symptoms than did LA and the main symptom was diarrhea. Consumption of 20 g lactose resulted in fewer symptoms than 20 g lactitol in both LA and LMT. On the basis of the hydrogen breath test, most LA tolerated 12 g lactitol without gastrointestinal symptoms except some flatulence whereas most LMT and LMI did not. Twenty g lactitol was not tolerated by both LA and LMT because there was diarrhea among the subjects, especially in LMT. Although the hydrogen breath analysis test is the best method for identification of lactose malabsorption, it is not the best method to identify lactitol intolerance. A hydrogen concentration of 15 ppm above the baseline level was found to be the best cut-off point to indicate lactitol intolerance although sensitivity was 85% and specificity only 38% in this study. It was further concluded that there is a greater susceptibility to lactitol in human lactose malabsorbers than in lactose absorbers. Our findings might be relevant for the limited use of lactitol in Thailand.

Small intestinal transit and digestibility of lactitol in Wistar rats.

The study was conducted to evaluate if the recovery of lactitol and its cleavage products varied when different doses of this disaccharide sugar alcohol (150 and 1,200 mg/kg body weight, respectively) were given by gastric gavage to unadapted male rats. Phenol red added to the test solution as marker dye served to determine the intestinal transit and distribution areas. Marker transit revealed that the test substance did not reach the cecum in all series. Gastric emptying was more retarded after the high dose. Administration of low doses did not alter intestinal transit and luminal volume as compared to control animals. But a much larger luminal volume was found in the third intestinal quarter after the high doses, although the marker transit through this segment was equal under all experimental conditions. The total gastrointestinal recovery of lactitol at 63.2 (+/- 3.9) and 75.5 (+/- 4.5)% was significantly different (p < 0.001) 1 hour after administration of 150 mg and 1200 mg/kg body weight, respectively. Only free sorbitol was detected in the gastrointestinal contents in both dosage groups. Based on these results and correcting the values for marker recovery (85% in both groups), it is reasonable to assume that the maximum amount of lactitol that can be hydrolyzed and absorbed by the small intestine is 11.2 and 25.2%, respectively, and not zero. In conclusion, the caloric availability of lactitol is dose-dependent and should be determined under normal conditions in which the laxative threshold is not exceeded.

Dose dependency of fermentation and the extent of renal excretion of palatinit (isomalt) in rats with respect to its energy value.

The impact of dose-dependent caloric salvage by microbial fermentation processes in the lower gut and the extent of renal excretion for the overall energetic availability of the alternative bulk sweetener Palatinit were investigated in rats. To evaluate the extent of dose-dependent fermentation a conventional and a germ-free rat model were used and fecal excretions of Palatinit after intragastric application were compared. Because of the lack of bacterial colonization in the gastrointestinal tract in germ-free rat the difference in fecal excretion of Palatinit between germ-free and conventional rat is mainly due to bacterial fermentation. To determine the amount of renal excretion of Palatinit the urine was collected. The experiments were conducted using different amounts of Palatinit (300 and 1,200 mg/kg body weight = mg/kg b.w.). Fecal excretions of Palatinit and its monomers (sorbitol and mannitol) were measured by high-performance liquid chromatography (HPLC) and for the determination of renal excretions a gas chromatography system was used. After the application of 300 mg/kg b.w. Palatinit only the breakdown product sorbitol could be recovered in the feces of germ-free rats (29% of the applied dose). No intact Palatinit could be found. In contrast, neither Palatinit nor the breakdown products sorbitol or mannitol could be detected in the feces of conventional rats after application of the same dose. After the application of the higher dose only small amounts of intact Palatinit were found in the feces of germ-free rats (average 12%). There was no intact measurable Palatinit in the feces of conventional rats. The fecal excretions of sorbitol and mannitol in the feces of the germ-free rats were 55% and 39%; in conventional rats only 21% sorbitol was excreted. Only traces of Palatinit, sorbitol or mannitol were found in the urine of conventional and germ-free rats after application of the low as well as the high dose. In conclusion, this study clearly shows the dose dependency of fermentation and therefore the dose dependency of the energetic (i.e., caloric) availability of this disaccharide sugar alcohol. In the calculation of the energy value of Palatinit the renal excretion of Palatinit and its monomers can be neglected.

Gastrointestinal transit and digestibility of maltitol, sucrose and sorbitol in rats: a multicompartmental model and recovery study.

Using data obtained with a dye marker and the gavage technique, the kinetics of gastrointestinal transit of different loads of sugar substitutes (maltitol, sorbitol) and sugar (sucrose) in the rat were analysed using a linear multicompartmental model over a range from the realistic to the non-physiologic high, of carbohydrate intake levels and using only a few experimental time points. The model gave detailed insight into intestinal propulsion and gastrocecal transit time. Rate constants of transport between the compartments investigated were determined; they showed characteristics which could be related to the substance and the dosage administered. Analyses of the gastrointestinal content and calculations of the intestinal net water movement showed that the digestibility and absorption of the disaccharide sugar alcohol, maltitol, in the small gut depended inversely on the dose ingested. For all substances tested, caloric availability in the small intestine was calculated. At a physiological low level of maltitol intake, the results also indicated an insignificant calorie-saving effect in comparison to sucrose, an effect based mainly on the slow absorption rate of the maltitol cleavage product sorbitol.

Microcalorimetric investigation into the metabolic activity of rat caecal flora in the presence of different sugars and sugar substitutes.

When adapting young rats to different sugar substitutes (sorbitol, PolydextroseR and PalatinitR), effects were seen in the caecal morphology and caecal content e.g. bacterial concentration, which did not occur when adapting rats to sugars (glucose, sucrose). For in vitro studies, anaerobic growth of caecal flora in thioglycollate medium with and without the respective substances was monitored by continuous measurement of heat production, optical density and pH. Additionally, biochemical analyses and light microscopic observations were performed in order to detect differences between adapted and non-adapted flora. In particular the microcalorimetric data furnished valuable information about alterations in bacterial metabolic activity after adaptation to sugars and sugar substitutes, and clearly indicated that all the substances tested influenced the metabolism of caecal flora.

[Experiences with the enzymatic determination of sugar and sugar substitutes in dietetic cake for diabetics (author's transl)]. / Erfahrungen mit der enzymatischen Bestimmung von Zucker und Zuckeraustauschstoffen in Diabetikerbackwaren.

Sorbitol and fructose were determined enzymatically in home-made and commercially produced cake for diabetics. In some commercial products, a loss of fructose depending upon the baking period was found. This loss of fructose is to be attributed to the Maillard reaction. The findings were confirmed by comparative studies will a reference cake.