Effects of oat and rye fractions on biliary and faecal bile acid profiles in Syrian golden hamsters (Mesocricetus auratus)

Reduction in circulating bile acid and restricted diffusion across the intestinal epithelium are associated with a decrease in blood cholesterol in the presence of oat β-glucan

Although oat (1,3:1,4)-β-glucan (BG) has been shown to decrease blood cholesterol in intervention trials, the detailed mechanism is not yet defined, but restricted reabsorption of bile acids (BAs) has been hypothesized. Using pigs as a model for humans we demonstrated that, compared to the control, BG added to the diet for 26 d caused decreases of 24% in blood total BAs (TBAs), 34% in total cholesterol (TC), and 57% in LDL cholesterol (LDL-C) (P < 0.01); decreases of 20% TBA in the midjejunum and terminal ileum (P < 0.01); increases of 80% in cecal total neutral sterols (TNSs) including cholesterol (P < 0.01); a 50% reduction in BA active transport across ex vivo ileum after 40 min (P < 0.001); and 32% decrease in jejunal microvillus heights with apparent increased goblet cell activity. The results suggest that BG not only physically hinders the active reabsorption of BAs and uptake of cholesterol, but also changes the BAs profile with lower circulating levels without excess excretion in the feces, thus resulting in reduced blood TC and LDL-C. Fermentation of sterols reaching the colon enhanced production of therapeutic ursodeoxycholic acid, suppressed toxic lithocholic acid, and decreased the possibility of cholesterol absorption by transforming the latter into coprostanol, a nonabsorbable NS.-Gunness, P., Michiels, J., Vanhaecke, L., De Smet, S., Kravchuk, O., Van de Meene, A., Gidley, M. J. Reduction in circulating bile acid and restricted diffusion across the intestinal epithelium are associated with a decrease in blood cholesterol in the presence of oat β-glucan.

Avena sativa (Oat), a potential neutraceutical and therapeutic agent: an overview

The aim of the present review article is to summarize the available information related to the availability, production, chemical composition, pharmacological activity, and traditional uses of Avena sativa to highlight its potential to contribute to human health. Oats are now cultivated worldwide and form an important dietary staple for the people in number of countries. Several varieties of oats are available. It is a rich source of protein, contains a number of important minerals, lipids, β-glucan, a mixed-linkage polysaccharide, which forms an important part of oat dietary fiber, and also contains various other phytoconstituents like avenanthramides, an indole alkaloid-gramine, flavonoids, flavonolignans, triterpenoid saponins, sterols, and tocols. Traditionally oats have been in use since long and are considered as stimulant, antispasmodic, antitumor, diuretic, and neurotonic. Oat possesses different pharmacological activities like antioxidant, anti-inflammatory, wound healing, immunomodulatory, antidiabetic, anticholesterolaemic, etc. A wide spectrum of biological activities indicates that oat is a potential therapeutic agent.

Dietary fibre-rich oat-based products affect serum lipids, microbiota, formation of short-chain fatty acids and steroids in rats

Wistar rats (ten per group) were fed either an oat-free control diet or a dietary fibre-rich test diet containing 500 g oat-based products/kg for 6 weeks. The oat-based products, containing 4–128 g/kg resistant starch, 30–92 g/kg β-glucan and 122–304 g/kg total dietary fibre, were oat flour extrudate, flour/Novelose (commercial resistant starch) extrudate (80:20 w/w), oat bran, bran/Novelose extrudate (80:20 w/w) and autoclaved oat flour. Serum total cholesterol decreased in the groups fed flour, flour/Novelose and bran/Novelose (P<0·05). In most of the test groups, count numbers of bifidobacteria were higher (P<0·001) and of coliforms were lower (P<0·05). The mass of the caecum walls and contents was greater in groups fed Novelose- and bran-containing diets (P<0·005). In all the test groups, pH values were lower in the intestinal contents (P<0·001), and caecal concentrations of acetate (P<0·001), propionate (P<0·05), butyrate (P<0·005) and total SCFA (P<0·001) were higher. The lowest concentrations of steroids were found in rats fed the autoclaved flour. In the other test groups, more bile acids appeared in the caecal (P<0·001) and colonic contents (P<0·005), as well as in the faeces, at week 6 (P<0·001). The highest bile acid excretion was found after feeding bran-containing diets. In the intestinal contents of all the test groups, more primary bile acids (P<0·001) appeared than in the control group. The excretion of steroids increased within the experimental period. Using extrusion technology, dietary fibre-rich oat-based products, which have beneficial physiological effects in rats, can be produced. Oat flour and bran are excellent sources for the preparation of directly edible oat products. Their nutritional properties can be further improved by the addition of resistant starch.

A buckwheat protein product suppresses 1,2-dimethylhydrazine-induced colon carcinogenesis in rats by reducing cell proliferation

This study was conducted to examine the effect of consumption of buckwheat protein product (BWP) on 1,2-dimethylhydrazine (DMH)-induced colon tumor in rats. Male growing Sprague-Dawley rats were fed diets containing either casein or BWP (net protein level, 200 g/kg; n = 20/group) for 124 d. The rats were gavaged weekly with DMH (20 mg/kg body) for the first 8 wk. Food intake and growth were unaffected by dietary manipulation. Dietary BWP caused a 47% reduction in the incidence of colonic adenocarcinoma (P < 0.05), but did not affect the incidence of colonic adenomas. BWP intake tended to reduce the number of colon adenocarcinomas (P = 0.16). Consumption of BWP significantly reduced cell proliferation and expression of c-myc and c-fos proteins in colonic epithelium. The results suggest that dietary BWP has a protective effect against DMH-induced colon carcinogenesis in rats by reducing cell proliferation.

Effects of rye bran, oat bran and soya-bean fibre on bile composition, gallstone formation, gall-bladder morphology and serum cholesterol in Syrian golden hamsters (Mesocricetus auratus)

The effects of rye bran, oat bran and soya-bean fibre on serum lipids, bile composition and gallstone formation were studied in male Syrian golden hamsters (Mesocricetus auratus). The control groups received fibre-free stone-provoking (O1 diet) or non-stone-provoking (O2 diet) diets. The serum cholesterol levels were lower for all groups fed on the diets supplemented with the dietary fibre sources compared with the control groups. The total content of bile acids in bile was higher in groups given rye-bran diets compared with the corresponding controls. The proportion of cholic acid was higher and that of chenodeoxycholic and lithocholic acid lower in the groups given rye-bran-, oat-bran- or soya-bean-fibre-supplemented diets, compared with the corresponding controls. The secondary:primary bile acid ratio was lower in the group given the rye-bran-supplemented O1 diet. The lithocholic:deoxycholic acid ratio was lower in the groups given rye-bran-, oat-bran- or soya-bean-fibre-supplemented diets than in the corresponding controls. A lower frequency of gallstones was observed only for the group receiving the rye-bran-supplemented O1 diet while the lithogenic index was lower in the groups given the rye-bran-supplemented O2 diet. A decreased epithelial volume density of the gall-bladder and an increased smooth muscular volume density were observed in animals given oat-bran- and rye-bran-supplemented O1 diets, whereas for the soya-bean-fibre-supplemented O1 diet, only the smooth muscular volume density was increased.