Per Tidehag

Effects of meal frequency and high-fibre rye-bread diet on glucose and lipid metabolism and ileal excretion of energy and sterols in ileostomy subjects.

Objective: To investigate the effect of a rye, high-fibre diet (HFD) vs a wheat, low-fibre diet (LFD), meal frequency, nibbling (Nib, seven times a day) or ordinary (Ord, three times a day), and their combined effects on blood glucose, insulin, lipids, urinary C-peptide and ileal excretion of energy, cholesterol and bile acids in humans.Design: LFD period with Nib or Ord meal frequency followed by an HFD diet with Nib or Ord meal frequency in randomized, crossover design.Setting: Outpatients of ileostomy volunteers were called for an investigation in research word.Subjects: A total of 10 subjects (two female subjects, age 34 and 51 y; eight males, mean age 54.4 y, range 43–65 y) participated in the experiment. All subjects were proctocolectomized for ulcerative colitis (mean 16.0 y, range 8–29 y before the study).Intervention: In total, 10 ileostomy subjects started with LFD for 2 weeks, the first week on either Nib (five subjects) or Ord (five subjects) and the second week on the other meal frequencies, in a crossover design, followed by a wash-out week, and continued with HFD period for 2 weeks in the same meal frequency manner. All foods consumed in both Nib or Ord regimens were identical and a high-fibre rye bread was used in the HFD period and a low-fibre wheat bread in the LFD period.Main outcome measures: Day-profiles of blood glucose, insulin and lipids, blood lipids before and after dietary intervention, and excretion of steroids in the effluents and C-peptide in the urine.Results: During the Nib regimen, plasma glucose and insulin peaks were lower at the end of the day with HFD compared with LFD. Urinary C-peptide excretion was significantly higher in the day-time on LFD compared with HFD (LFD-Ord vs HFD-Ord, P<0.01; LFD-Nib vs HFD-Nib, P<0.01). Plasma free-cholesterol, total cholesterol, triglycerides and phospholipids were significantly higher (P<0.05) after LFD than after HFD with the Nib regimen. A higher excretion of energy (P<0.05) and chenodeoxycholic acid (P<0.05) were observed with HFD compared with LFD regardless of meal frequency. A higher daily excretion of cholic acid, total bile acids, cholesterol, net cholesterol and net sterols (P<0.05) was observed on HFD compared with LFD with the Nib regimen.Conclusions: An HFD decreased insulin secretion measured as a decreased excretion of C-peptide in urine and as decreased plasma insulin peaks at the end of the day during a Nib regimen. The smoother glycaemic responses at the end of the day during a Nib regimen may be a consequence of a second meal phenomenon, possibly related to the nature of dietary fibre complex.Sponsorship: This study was supported by grants from the Swedish Council of Forestry and Agricultural Research (SJFR).

A comparison of iron absorption from single meals and daily diets using radioFe (55Fe, 59Fe)

The purpose of the present study was to compare two measures of Fe absorption, one from single meals and the other from daily diets. Ten ileostomy subjects were given the same low-fibre composite diet for all three meals each day for five consecutive days. After 3 weeks the experiment was repeated with a high-fibre diet. The morning meal constituted one-seventh of the total daily diet intake, the mid-day meal two-sevenths and the evening meal four-sevenths of the total daily diet intake. On days 4 and 5 of each diet period the morning meal was labelled with 55Fe and all three meals were labelled with 59Fe. The activities retained in the subjects 19 d later showed the Fe absorption from the low-fibre diet measured from the morning meals to be almost 80% greater than the average Fe absorption measured from all meals during the same 2 d. With the high-fibre diet the absorption from the morning meals was less than 50% greater than the average for all meals but the difference was not significant. We suggest that all meals of the day should be labelled with radioFe in order to avoid inflating the measures of Fe absorption.

Cadmium accumulation from diets with and without wheat bran in rats with different iron status

Abstract The purpose of the present study was to determine to what extent the accumulation of cadmium in rats with low, marginal and high iron status is affected by the presence of bran in the diet. High iron status caused the total and fractional accumulation of cadmium from both the wheat endosperm and wheat bran diets to be decreased by almost half compared to that in the low iron status rats. The inclusion of wheat bran in the diet increased the total accumulation of cadmium in the liver by approximately the same proportion in all three iron status groups. While the results do not exclude the possibility that the availability of cadmium for absorption from wheat bran is less than that from wheat endosperm in rats with high iron status, no appreciable effect of mineral binding factors in bran on the fractional cadmium accumulation in the liver could be demonstrated in the low and marginal iron status groups. Thus, for rats with less than adequate iron status, the inclusion of wheat bran in the diet should increase the cadmium intake and its accumulation in the body by the same proportion.

High-fiber rye diet increases ileal excretion of energy and macronutrients compared with low-fiber wheat diet independent of meal frequency in ileostomy subjects.

Background Whole-grain foods and cereal dietary fiber intake is associated with lower body weight. This may partly result from lower energy utilization of high-fiber diets. Objective In the present study, the impact on ileal excretion of energy and macronutrients in response to a rye bread high-fiber diet compared to a refined wheat low-fiber diet was investigated. Furthermore, the effect of meal frequency on apparent absorption of nutrients was studied for the first time. Design Ten participants that had undergone ileostomy consumed standardized iso-caloric diets, including low-fiber wheat bread (20 g dietary fiber per day) for 2 weeks followed by high-fiber rye bread (52 g dietary fiber per day) for 2 weeks. The diets were consumed in an ordinary (three meals per day) and a nibbling (seven meals per day) meal frequency in a cross-over design. Ileal effluents were collected during 24 h at the third day of each of the four dietary periods and analyzed for gross energy and nutrient contents. Results The results showed that intake of rye bread high-fiber diet compared to the refined wheat low-fiber diet caused an increase in ileal excretion of energy and macronutrients. The effect was independent of meal frequency. This suggests that a high intake of rye may result in lower availability of macronutrients for small intestinal digestion and absorption. A regular intake of rye may therefore have implications for weight management.

The extent of coprophagy in rats with differing iron status and its effect on iron absorption.

The purpose of this study was to determine the prevalence of coprophagy in rats with differing iron status and its effect on the measurement of iron absorption from test meals with and without bran. Two experiments were performed using radioisotope-labelled microspheres added as a non-digestible marker for the ingested faeces and the diet and 59Fe added as a marker for the non-haem iron in the test meal. In this study, coprophagy occurred at group mean rates of between 5 and 22% and was independent of the iron status of the rats or the presence or absence of bran in the diet. The relative absorption of iron, measured as the retention of 59Fe from a single meal, was affected to the same extent in groups with the same iron status, if it was affected at all. Thus comparisons of iron absorption from diets with and without bran should not be affected by coprophagy.

The availability of iron, zinc and cadmium to rats from composite diets with different cereal grains

Abstract Many investigations have been reported in which the effects of varying the concentration of a single factor in grain diets on the availabilities of minerals for absorption have been studied. The purpose of this study in rats was to determine the effects on iron, zinc and cadmium availability of substituting whole grain wheat, oats, barley or rye for iron-supplemented endosperm wheat in a composite diet with one part grain flour and one part non-fat, dried milk with maize oil and vitamins. Iron concentrations varied by a factor of 3 among these diets, zinc by 1.5, cadmium by 5, and both fiber and phytate by a factor of 3.5. The absorption of 59 Fe and 65 Zn from test meals of the diets and the concentrations of iron, zinc and cadmium in selected tissues and body fluids after five weeks on the grain diets were used as independent measures of the mineral availabilities from these diets. Absorption of iron from endosperm wheat and, to a lesser extent, zinc from oats and rye appears to have been overestimated, most likely due to incomplete exchange of the radioisotopes with the supplemented or endogenous minerals in the grains. The variations in the concentrations of iron and cadmium among the diets were by far the most important factors determining the availabilities of these minerals to the rats. The fractional availabilities of iron and zinc were negatively related to the diet phytate concentration and the fractional availability of cadmium was negatively related to the iron status of the rats. The results indicate that substitution of whole grain wheat for endosperm wheat in the diet will increase cadmium accumulation considerably while substitution of oats, barley or rye should result in nearly the same or lower cadmium accumulation. Due to the low availability of iron in barley and rye, substitution of either grain for iron-supplemented endosperm wheat may compromise iron status. As the diets in this study are similar to baby formulas and breakfast cereals, porridge or a sandwich with milk, the probability that these results in rats are applicable to humans strongly suggests that studies similar to this be carried out in humans.

The Availability of Zinc, Cadmium and Iron from Different Grains Measured as Isotope Absorption and Mineral Accumulation in Rats

The purpose of this study in rats was to determine if the absorption and accumulation of zinc, cadmium and iron differ amoung diets based on different grains and, if so, what differences among the grains might account for the differences in mineral absorption.

Digital dentistry calls the change of ceramics and ceramic processes

ABSTRACT Since the start of the new digital impression-taking era which started around 2008 with the introduction of the 3M Lava COS, a slow transformation is gaining momentum and it looks as if this and next year will have a broad impact on the clinicians. From being merely a way of replacing impressions now the total digital workflow enters the industry. This means a whole new way of thinking and a new way to produce prosthetic work where a reproducible constant quality can be achieved. An obvious development of improved ceramic materials that simultaneously can satisfy the mechanical, bio- and aesthetic demands of the prostheses and the corresponding technologies for production that would work for the clinic digital workflow is out of the expertise of the dentists. This calls for a cross-disciplinary collaboration with the experts in the communities of ceramics and digital manufacturing.