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We sought to determine whether radiation to the colorectum had an impact on parameters of hippocampal neurogenesis and, if so, whether it could be modulated by a fiber-rich diet. Male C57BL/6J mice were fed a diet containing bioprocessed oat bran or a fiber-free diet, starting two weeks before colorectal irradiation with 4 fractions of 8 Gray or sham-irradiation. Diets were then continued for 1, 6 or 18 weeks, whereafter parameters of hippocampal neurogenesis were analyzed and correlated to serum cytokine levels. No statistically significant changes in neuronal markers or cell proliferation were found at one week post-irradiation. Six weeks post-irradiation there was a decreased cell proliferation in the subgranular zone that appeared slightly more pronounced in irradiated animals on a fiber-free diet and increased numbers of immature neurons per mm2 dentate gyrus in the irradiated mice, with a statistically significant increase in mice on a fiber-rich diet. Microglial abundancy was similar between all groups. 18 weeks post-irradiation, a fiber-free diet had reduced the number of immature neurons, whereas irradiation resulted in an increase. Despite this, the population of mature neurons was stable. Analysis of serum cytokines revealed a negative correlation between MIP1-α and the number of immature neurons one week after irradiation, regardless of diet. Our findings show that pelvic radiotherapy has the potential to cause a long-lasting impact on hippocampal neurogenesis, and dietary interventions may modulate this impact. More in-depth studies on the relationship between irradiation-induced intestinal injury and brain health are warranted. (Less)

Processing affects the composition, structure and physico-chemical characteristics of dietary fibres, and further changes can occur along the gastro-intestinal tract before entering the colon where undigested carbohydrates may serve as a substrate for the microbiota. To elucidate the effects of dietary fibre characteristic and the impact of processing on the digestive fate of dietary fibre components, in the stomach and the small intestine, a dynamic gastrointestinal in vitro model (TIM-1) was used. Three barley malt and one brewers’ spent grain, with different contents of soluble fibre, arabinoxylan (total and soluble), and β-glucan with varying Calcofluor average molecular weight (Mcf) and molecular weight distribution were evaluated in the in vitro model. Additionally, a rat model was used to study the colonic fermentation of the dietary fibre components in the barley products. The transit time through the stomach and small intestine of the in vitro model was slowest for barley malts with the highest content of soluble fibre and β-glucan. The β-glucan Mcf decreased with digestion time for all test meals, and the molecular weight distributions in the various barley products differed markedly. The highest β-glucan Mcf was found for Cinnamon malt, which also contained the highest proportion of soluble fibre. The hindgut fermentation of fibre and the proportions of caecal propionic acid were highest in rats fed barley products high in soluble fibre, β-glucan (content and Mcf), soluble arabinoxylan, and with slowest transit during digestion in the in vitro model.

A method based on hollow-fibre liquid phase microextraction combined with gas chromatography was developed for determination of specific bile acids in caecal materials of rats. Nine unconjugated bile acids, including the primary bile acids (cholic acid, chenodeoxycholic acid and α-muricholic acid) and the secondary bile acids (lithocholic acid, deoxycholic acid, ursodeoxycholic acid, hyodeoxycholic acid, β-muricholic acid and ω-muricholic acid) were quantified. Extraction conditions were evaluated, including: sample pH, type of organic solvent and amount of caecal material to be extracted. To compensate for sample matrix effects during extraction the method of standard addition was applied. The satisfactory linearity (r(2)>0.9840), high recovery (84.2-108.7%) and good intra-assay (6.3-10.6%) and inter-assay (6.9-11.1%) precision illustrated the good performance of the present method. The method is rapid, simple and capable of detecting and determining bile acids with limit of detection (LOD) ranged from 0.002 to 0.067μg/mL and limits of quantification (LOQ) varied from 0.006 to 0.224μg/mL. The results indicated that the concentration of some secondary bile acids, which usually are associated with health problems, were lower in rats fed with fermentable dietary fibre compared with a fibre free control diet, while the concentration of primary bile acids, usually connected with positive health effects, were higher in rats fed with diets containing dietary fibre. Of the dietary fibres, guar gum and to some extent the mixture of pectin+guar gum had the most positive effects. Thus, it was concluded that the composition of bile acids can be affected by the type of diet.

Structure and health effects of inulin-type fructans have been extensively studied, while less is known about the properties of the graminan-type fructans in wheat. Arabinoxylan (AX) is another important indigestible component in cereal grains, which may have beneficial health effects. In this study, the fructan content in milling fractions of two wheat cultivars was determined and related to ash, dietary fibre and AX contents. The molecular weight distribution of the fructans was analysed with HPAEC-PAD and MALDI-TOF MS using 1H NMR and enzymatic hydrolysis for identification of fructans. The fructan content (g/100 g) ranged from 1.5 ± 0.2 in flour to 3.6 ± 0.5 in shorts and 3.7 ± 0.3 in bran. A correlation was found between fructan content and dietary fibre content (r = 0.93, P < 0.001), but with a smaller variation in fructan content between inner and outer parts of the grain. About 50% of the dietary fibre consisted of AX in all fractions. The fructans were found to have a DP of up to 19 with a similar molecular weight distribution in the different fractions.

The extraction procedure for analysis of the raffinose family oligosaccharides (RFOs) in blanched leguminous vine peas was optimized. For this purpose, 25 pea samples from different cultivars and of different maturity were chosen at random. The effect of blanching was also studied in four cultivars. The yield of oligosaccharides was almost double on average when extracted with 50% ethanol as compared with 80% ethanol. This was generally valid for all three oligosaccharides, with some exceptions for verbascose, where 80% ethanol was shown to be as effective as 50% ethanol. Extraction at room temperature and at boiling temperature gave similar yields, while 15 min of extraction gave lower yields than 30 and 60 min of extraction, which were similar. The loss of oligosaccharides following blanching was 32% on average, with verbascose showing the highest loss (56.4%), followed by raffinose (28.4%) and stachyose (16.3%). It can be concluded that the procedure used for extraction is of great importance when analysing the RFOs in immature peas, and that there is considerable loss of these sugars during blanching, which is the process commonly used to prepare the frozen commercial product. (c) 2006 Elsevier Inc. All rights reserved. (Less)

The effect of Bifidobacterium lactis (Bb-12) and Lactobacillus salivarius (UCC500) on the formation of carboxylic acids (CAs) was studied in the hindgut of rats fed pectin, inulin of low solubility, and lactitol. When the pectin diet was supplemented with Bb-12, the formation of CAs was larger throughout the colon of rats, due to increased formation of acetic acid (P < 0.01) and, in the distal part of the colon, also because of propionic and butyric acids (P < 0.01). In rats fed pectin and UCC500, there was a shift in the formation of CAs from the cecum to the distal colon. Thus, the cecal pool of CAs in the rats was lower (P < 0.05), whereas the concentration of CAs in the distal part of colon was larger (P < 0.01) than without this strain. Concerning the slowly fermentable inulin, there was a greater formation of CAs in the cecum (P < 0.05) of rats, especially propionic acid, and a lower formation in the distal part of the colon (P < 0.01) when the diets were supplemented with Bb-12, whereas UCC500 had no effect except for a lower proportion of acetic acid in the distal part of the colon (P < 0.001). In rats fed lactitol and Bb-12, the concentration of CAs was lower in the distal part of colon (P < 0.001) than without this strain, whereas the cecal pool of CAs was greater in rats supplemented with UCC500 (P < 0.001). We conclude that the probiotic bacteria affect the amount, the pattern, and the site of release of CAs in the hindgut of rats, but the combination of pre- and probiotics is of great importance for the outcome.

The effect of blanching and treatment with white vinegar containing acetic acid on dietary fibre, low-molecular-weight carbohydrates and glucosinolates was studied in two cultivars of white cabbage (Heckla and Predikant). The total content of dietary fibre and low-molecular-weight carbohydrates was similar in both cultivars (24 and 60 g/100 g DM, respectively), while the distribution between soluble and insoluble fibre differed (19% was soluble in Heckla versus 26% in Predikant, P < 0.01). Further, Heckla contained higher amounts of glucose and sucrose, while the content of fructose and total glucosinolates was lower than in Predikant. The content of individual glucosinolates differed between the two cultivars. During blanching there was a loss of dry substance (30-34 g/100 g DM), where low-molecular-weight carbohydrates primarily explained the loss (82-90%), but some of the loss was also dietary fibre (about 8%), both soluble fibre containing uronic acids (mainly Predikant) and insoluble ones containing glucose (mainly Heckla). The glucosinolate levels decreased substantially in both cultivars, although the total loss was higher in Predikant (74%) than in Heckla (50%). The individual glucosinolates were affected to different degrees (15-91%). During souring with acetic acid, the content of dietary fibre (primarily insoluble ones) decreased further, while the content of low-molecular-weight carbohydrates was less affected. The total content of glucosinolates was not affected in Heckla but was further reduced in Predikant. There was, however, a substantial increase in 4-methoxyglucobrassicin in both cultivars. It is concluded that blanching and souring decrease the content of carbohydrates and glucosinolates to a great extent and both cultivars behaved similarly. However, individual components were affected differently in the two cultivars. (c) 2005 Published by Elsevier Ltd. (Less)

Knowledge of how the content of low molecular weight carbohydrates (LMWC), including the raffinose family oligosaccharides (RFO; raffinose, stachyose and verbascose), changes in unripe peas (Pisum sativum) around harvest time, is today limited. An early and a late maturing cultivar of peas were harvested with 24 h of each other on seven different occasions, of which three were chosen for this study. The pea samples were divided into three groups by size and brine grading, and then analysed with regard to the content of low molecular weight carbohydrates. The content of raffinose and stachyose increased in all groups during a period of 5 days. Peas that sank (sinkers) in the brine grading test had a higher content of raffinose and stachyose and a lower content of sucrose than floating peas, indicating that sinkers have reached a greater degree of maturation. The content of verbascose remained the same or decreased during the study period. In conclusion, the date of harvesting green peas for freezing affects the contents of RFO.

The ability of different lactic acid bacteria to influence the physicochemical characteristics (content, viscosity and molecular weight) of dietary fibre in beta-glucan-rich barley and oat concentrates was investigated. The cultures used were Lactobacillus acidophilus and the exopolysaccharide producing strain Pediococcus damnosus 2.6, together with the yoghurt culture, V2 (a mixture (1:1) of Lactobacillus delbrueckii subsp. bulgaricus and Streptocoecus salivarius subsp. thermophilus). Two methodologies, one including filtration and another centrifugation-dialysis, to quantify the dietary fibre, were compared. The centrifugation-dialysis method generally gave significantly (P < 0.05) higher values than the filtration method (for example, 79.8 g/100 g DW versus 59.6 g/100 g DW for the total fibre in the native barley fibre concentrate) with the exception of soluble barley fibres. The insoluble fibre content was found to decrease after fermentation (58.8 g/100 g DW to 39.0/37.0 g/100 g DW in barley and 26.0 g/100 g DW to 4.5/3.0 g/100 g DW in oats as analysed by the centrifugation-dialysis method). The soluble fibre in the barley fibre concentrate was apparently not affected by fermentation, while contents and maximum viscosities of the soluble fibre in oat fibre concentrates decreased after fermentation. However, the molecular weight was apparently not affected. (C) 2004 Elsevier Ltd. All rights reserved. (Less)

The possibility of using high hydrostatic pressure (HHP) to modify the physico-chemical properties of dietary fibre polysaccharides in white cabbage (Brassica oleracea var. capitata) was studied. Two cultivars (Heckla and Predikant) were subjected to high pressure treatment (400 and 500 MPa) at different temperatures (20, 50 and 80 °C). The total dietary fibre (TDF) content was only slightly affected by HHP. However, considerable effects were generally seen in the distribution between soluble and insoluble fibre at increased pressure. When the pressure applied was 400 MPa, the proportion of soluble fibre in the cultivar Heckla was reduced at all temperatures. No additional effects were seen when the pressure was increased to 500 MPa. For the cultivar Predikant the pressure generally had to be increased to 500 MPa to attain the same effects. An exception was pressure treatment at 80 °C, where a pressure of 400 MPa was sufficient. The total dietary fibre content in unprocessed cabbage (0.1 MPa and 20 °C) was lower in the cultivar Heckla than in Predikant due to lower contents of insoluble polymers containing glucose and uronic acids. This was the case for most temperatures and pressures. It is concluded that the solubility of the dietary fibre in white cabbage can be affected by high pressure temperature treatment, which may be of importance when producing foods with specific health effects.

The molecular weight distribution and the viscosity of water-soluble polysaccharides isolated from carrots were investigated after different types of heat-treatment, commonly used when preparing food. The materials studied were blanched, boiled, microwaved and canned. Freezing, without any heat-treatment, was used as a reference process. The water soluble polysaccharides were isolated using two different procedures, i.e. before and after enzymic digestion of protein and starch. Only minor differences in molecular weight distribution between frozen and blanched materials could be detected by gel-filtration. However, when the carrots were further heat-treated, i.e. boiled, microwaved and canned, there was an increase in both the high molecular and the low molecular weight fractions of soluble polysaccharides (especially pectic substances) isolated after digestion of protein and starch. This indicated a solubilization of originally isoluble material, as well as a degradation of the soluble high molecular weight material. On the other hand, in the polysaccharide fraction isolated directly, i.e. without any degradation of protein and starch, there was an increase only in the low molecular weight fraction and only when the materials were microwaved and canned. The viscosity of polysaccharides isolated without degradation of protein and starch could be correlated with the extent of degradation of the polysaccharides, and thus also with the degree of heat-treatment, in the following order: freezing, blanching, boiling, and canning. However, the viscosity of soluble fibre isolated after degradation of protein and starch was similar and low for all materials studied.

Cereal dietary fibre constitutes about half of the total fibre intake in Sweden. The amount of fibre available is 21 g/person/day or 1·75 g/MJ. Increased faecal bulk and shortening of intestinal transit time are well-documented effects, that are inversely proportional to the fermentability of the dietary fibre. Wheat bran, oat husks, and corn bran are fibre sources with high bulking effect, whereas fibre from the endosperm of cereals is more extensively fermented. Resistant starch in processed cereals has properties similar to dietary fibre, and must be considered in analysis as well as regarding physiological effects of dietary fibre. Oat groats and oat bran have serum cholesterol lowering effects related to the viscous soluble β-glucans. Rye and barley contain similar levels of viscous soluble fibre but are not as thoroughly investigated. Effects on postprandial glucose and insulin levels are also partly related to viscous soluble dietary fibre, but structural properties in, e.g., whole kernels and pasta products are more important in this respect. Phytate in whole grain flour and bran preparations inhibits iron and zinc absorption in single meal tests. Its role for mineral status in persons consuming a mixed, Western diet remains to be established.

The ability of soluble fibre fractions isolated from three different cereals (barley flour, whole grain rye flour and oat bran) to bind copper(II), cadmium(II) and zinc(II) ions has been studied using a potentiometric method. Considerable association was found between all fibre fractions and metals investigated. The ability of the metal ions to form complexes was found to be in the order Cu(II) > Zn(II) ≈ Cd(II) for all cereal fibres. The order of interaction for the fibres with metal ions was barley > oats ≈ rye. Between pH 3·5 and 5 phytic acid was an important complexing agent, especially for oats. No metal complexing ability was found for pure β-glucans, isolated from barley.

The fermentative breakdown and fecal bulking capacity of dietary fiber from various vegetables (carrots, rutabagas, peas, green beans and Brussels sprouts) were evaluated in balance experiments in rats. The excretion of bile acids, protein and fat was also studied. The addition of blanched vegetables providing 10 g of fiber/100 g of diet caused a two-(rutabagas) to threefold (carrots) increase in fecal dry weight compared to that with a basal fiber-free diet. With green beans and Brussels sprouts, only about 25% of the fecal dry weight could be accounted for as fiber, whereas with the other investigated vegetables, 40-47% was fiber. Of the remaining part, 11% on average was fat, and 18% was crude protein. Fiber in carrots and peas was the least degraded, with approximately 47% of the polysaccharide intake being excreted in feces. By contrast, the breakdown of the fiber in green beans and Brussels sprouts was more extensive, with a mean of 23% of the polysaccharides being recovered. Among individual fiber constituents, glucose, mannose and uronic acids were least fermented, with considerable differences between vegetables. Total excretion of bile acids was reduced only when Brussels sprouts were added, whereas the concentration of fecal bile acids was lowered with all vegetables except rutabagas. However, no uniform change in fecal bile acid pattern could be detected.

The fermentative breakdown of dietary fibre in raw and popped whole-grain wheat products was investigated by using rat balance dietary experiments. The faecal excretion of total dietary fibre was 74% with raw wheat, compared with 58% with the ‘severely’ popped product. The increased fermentability, could be partly related to an increased proportion of soluble fibre, but also to the formation of acid-insoluble material, which was easily degraded by the microbial flora. This material was formed during popping and, on analysis, appeared as Klason lignin. It consisted mainly of Maillard reaction products formed from protein. Thus, Maillard products may contribute to the apparent dietary fibre content in processed cereals.

The formation of in vitro resistant starch (RS) during autoclaving and freeze-drying of wheat starch suspension was evaluated. A substantial amount of starch, up to 8% (dry weight basis), was rendered resistant to amylases during heat-treatment unless solubilised in KOH, whereas freeze-drying had only marginal effects. Heat-treated wheat starch was incorporated into test diets to provide different levels of RS (0–5 %). The digestibility of starch was measured in vivo through balance experiments in normal rats and in rats treated with Nebacitin to suppress hind-gut fermentation. RS remained essentially undigested also in vivo. However, like certain types of dietary fibre, RS was readily metabolised (80–92 %) by the hind-gut microflora. Starch analysed with an enzymic method, in vitro accessible starch (AS), seemed to correspond to starch digestible in vivo. The in vivo digestibility of AS was close to 100 % whether Nebacitin was present or not. Energy utilisation decreased significantly with increasing level of RS in the diet. The biological value of dietary protein increased with increasing intake of RS in normal rats whereas no effect was noted in animals treated with Nebacitin. We conclude that RS formed during heat-treatment should be regarded as an easily fermentable dietary fibre component.

The digestibility of starch in white wheat bread was studied. Raw wheat starch and raw wheat flour were used as reference materials. The extent of digestion and absorption in vivo was evaluated through balance experiments in rats given test diets with and without addition of the antibiotic, Nebacitin, to reduce the fermentation in the hind-gut. As judged from a high faecal recovery of dietary fibre constituents in rats fed a wheat flour diet with Nebacitin, this drug significantly reduced the microbial activity in the hind-gut. Only minute amounts of starch could be detected in faeces of rats whether Nebacitin was present or not, indicating that pure wheat starch as well as starch in wheat bread and raw wheat flour was almost completely digested and absorbed in the rat small intestine. However, during baking, a fraction of the starch (0·6%–0·9%, dry basis) was rendered resistant to enzyme digestion in vitro unless solubilised in KOH. This modified starch fraction also remained undigested in vivo, but was readily metabolised by the hind-gut microorganisms, thus having physiological properties similar to those of dietary fibre. It is therefore recommended that resistant starch formed during baking (i.e. that rendered resistant to enzymic digestion as measured in vitro) should be regarded as dietary fibre rather than as dietary starch.

The fermentation of dietary fibre in wheat, rye, barley, sorghum, rice and maize was investigated in balance experiments with rats. Two different extraction rates, 100% and approximately 65%, were investigated for each cereal grain. In the case of maize, whole maize, and dehulled maize that had been ground and sieved so that it contained mainly endosperm, were investigated. Except for sorghum, dietary fibre in low-extraction flours was fermented to a greater extent than that in whole-grain flours. The sugar monomer compositions of the fibres at low and high extraction rates were similar for wheat and rye, but their susceptibilities to fermentation by bacterial enzymes were quite different. This indicates that a high proportion of soluble fibre and a low content of lignin improves the fermentability of the fibre. Further, barley, rice and sorghum fibre in refined flours, all of which consisted mainly of non-lignified glucans, were fermented more extensively when the proportion of soluble fibre was high. Addition of cellulose to diets containing wheat flour did not change the susceptibility of the wheat fibre to bacterial fermentation. Starch was demonstrated in faeces from rats fed wheat, sorghum and whole-grain rye flours. This starch represented 17–61 % of the total faecal glucan, but constituted less than 1% of the starch intake.

The binding of copper, cadmium and zinc ions to some soluble and gelforming types of dietary fibre (guar gum, low and high methoxylated pectin and sterculia gum) has been investigated potentiometrically. Considerable binding was found to low methoxylated pectin, but the binding to sterculia gum and high methoxylated pectin was less pronounced. The binding to guar gum was negligible. Thus, the formation of complexes seemed to be due to the proportion of free carboxyl groups. The amount of added metal bound to sterculia gum was proportional to the fibre concentration, whereas the pectins showed increased binding at higher fibre concentrations. This was possibly due to intermolecular interactions between the polymers and metal ions. The order of complex formation ability to the fibres investigated was different for different metals. To low methoxylated pectin the order Cu>Zn ⪢ Cd was observed.

The content of minerals and dietary fibre in different fractions of oats was investigated. The oat kernel (pericarp, testa, germ, aleurone, endosperm), accounting for 70 % of the oat seed, had a dietary fibre content of 11·5 g/100 g (dry weight basis); of this 23 % was soluble fibre components, mainly β-glucans. In contrast to most other cereals the amount of soluble fibre was distributed throughout the whole kernel. The oat husk, accounting for the remaining 30 %, has a considerably higher dietary fibre content than the kernel, 83·9 g/100 g. Most of the fibre in the husk (~ 99 %) was insoluble polymers containing cellulose and considerable amounts of xylans and lignin. The minerals associated with the fibre complex in the husk were mostly (~ 97 %) present in the insoluble fibre fraction (50 % of the Si and 30 % of the K). On the other hand, most (~ 70%) of the minerals in the kernel, were associated with the soluble fibre components (> 50% of the Ca, Fe, Mn and P), probably the β-glucans and/or the phytic acid. Fe and Cu were the only minerals that were found to any greater extent in the insoluble fibre fraction in the kernel (~ 20%). Most of the phytate (> 90%) was found in the soluble fibre fraction.

Zusammenfassung Die Haptoglobinkonzentration wurde in 250 Serumproben (Gesunde und Kranke) mit Papierelektrophorese und Peroxidase-Titrierung, nach jayle , bestimmt. Die Resultate beider Methoden sind konkordant. Die Streuung der Normalwerte (an 150 Serumproben von Blutgebern bestimmt) ist gross. smithies hat mit Gelelektrophorese drei vererbbare Haptoglobingruppen in Evidenz gebracht (Hp I, IIa, IIb). Eine Analyse unseres Normalmateriales mit dieser Technik zeigt dass die Streuung der Normalwerte in den beiden homozygoten Gruppen bedeutend kleiner ist als in dem gesamten Material. Die Identitat der von smithies beschriebenen Eiweissfraktion mit dem von uns bestimmten Haptoglobin wurde durch Resultate von Untersuchungen mit intravenoser Hamoglobinzufuhr stark unterstutzt.