Dose-dependent effects of polyphenolic extracts from green tea, blue-berried honeysuckle, and chokeberry on rat caecal fermentation processes.

The physiological status of the colon or ceacum is known to be very important for the host organism. Therefore, the aim of this study was to estimate the influence of high doses of polyphenolic extracts from chokeberry (CH), blue-berried honeysuckle (H), and green tea (GT) on fermentation processes in the caecum and caecal parameters of rats fed casein diets. In a 4-week experiment, 35-day-old rats were fed diets containing 0.4, 0.8, and 1.2 % of pure polyphenols. The greatest weight of digesta was recorded in rats fed 1.2 % of GT extract, and these animals were also characterised by having the lowest content of dry matter. Supplementation of diets with the extracts of interest caused a reduction in pH values and ammonia concentrations in caecal digesta in comparison to control animals. The results of a two-way analysis of variance indicated dose-dependent (except for 0.4 % supplementation) inhibition of enzymatic activity compared to control animals. Introduction of CH and H extracts significantly reduced the activity of ß-glucuronidase compared to rats fed tea diets. Two-way analysis of variance showed a significant decrease in volatile fatty acids concentration in rats fed diets supplemented with H and CH extracts in comparison to control and tea-fed rats. The obtained results showed that the extracts tested can distinctly influence caecal parameters and metabolism.

Comparative effect of green tea, chokeberry and honeysuckle polyphenols on nutrients and mineral absorption and digestibility in rats.

BACKGROUND/AIMS: Natural polyphenols are chemically and biologically active. This study aimed at examining the physiological effects of high doses of polyphenol extracts from green tea and new polyphenol-rich sources (chokeberry and honeysuckle fruits) on nutrient absorption. METHODS: 32 male Wistar rats were divided into four groups and fed a diet supplemented with one of the three polyphenolic extracts (at 0.4%) or a control diet for 4 weeks. A perfusion technique was used to study the effects at intestinal level. Pure polyphenols from the three sources were introduced into perfusion fluid at a concentration of 0.4% and allowed to cross the intestinal tract in 1.5 h. RESULTS: In the perfusion experiment, addition of the extracts caused a strong and statistically significant reduction in absorption of the selected nutrients (water, glucose, cholesterol, amino acids and minerals) compared to control animals. In the nutritional experiment, we recorded a slight decrease in diet utilization and growth in rats on polyphenolic diets relative to control group. In the same experiment, we observed a reduction of Zn and Cu absorption, but this was not accompanied by diminished concentrations in the bone femur. CONCLUSIONS: The presence of the polyphenolic extracts in the perfusion liquids significantly reduced absorption from the small intestine, but the nutritional experiment did not confirm deleterious consequences of the consumption of high extract doses.

Caecal parameters of rats fed diets supplemented with inulin in exchange for sucrose.

The effects of different modes of inulin supplementation on caecal fermentation were evaluated in rats. Groups S and IN were fed diets containing 5% of sucrose or inulin, respectively, for the whole experimental period of 40 days. Group IN/S was fed IN and S diets, whereas group S/IN was fed S and IN diets, in the first and the second 20-day period, respectively. Groups IN(up) and IN(down) were fed diets in which the content of inulin increased from 1-5% and decreased from 5-1%, every 8 days, respectively. The common effects of inulin on caecal fermentation, i.e. enlargement of tissue, acidification of digesta, a decrease in activities of potentially harmful bacterial enzymes (beta-glucuronidase and beta-glucosidase), and an increase in the total volatile fatty acids concentration and pool, were especially observed in the IN, S/IN and IN(up) groups. The results suggested that the intensity of caecal fermentation is increased when inulin is present at a relatively high dietary level and that these changes are easily reversible after inulin withdrawal from feed.

Nutritional assessment of raw and germinated pea (Pisum sativum L.) protein and carbohydrate by in vitro and in vivo techniques.

OBJECTIVE: We assessed the effect of germinating Pisum sativum L. variant Arvense cv. Esla for 3 and 6 d in darkness on the chemical composition and nutritive utilization of protein and carbohydrates. METHODS: Nutritional assessment of protein and carbohydrates was based on chemical analysis of raw and germinated pea flours and in vitro and in vivo rat balance methodologies. RESULTS: Germination caused a notable decrease in alpha-galactoside content and significant increases in sucrose, glucose, and fructose. The ratio of available starch to total starch increased as a consequence of processing. The content of vitamin B2 increased significantly, whereas no significant change was observed in vitamin B1 content in germinated peas. Protein digestibility assessed with an in vivo technique (apparent digestibility coefficient) or as the percentage of dialyzable nitrogen increased significantly as a result of germination in contrast to what was observed with the in vitro pH-drop methodology. Daily food intake, nitrogen absorption and balance, percentage of retained versus absorbed nitrogen, protein efficiency ratio, and the index of available carbohydrates were significantly improved by germination for 3 d and significantly decreased by germination for 6 d. CONCLUSIONS: Germination of pea seeds for 3 d significantly improves palatability of these seeds and the nutritive utilization of protein and carbohydrates.

Nutritional evaluation of pea (Pisum sativum L.) protein diets after mild hydrothermal treatment and with and without added phytase.

The effect of mild hydrothermal treatment and the addition of phytase under optimal conditions (pH 5.5, 37 degrees C) on the nutritive utilization of the protein of pea (Pisum sativum L.) flour was studied in growing rats by examining the chemical and biological balance. Mild hydrothermal treatment produced reductions of 83, 78, and 72%, respectively, in the levels of alpha-galactosides, phytic acid, and trypsin inhibitors and also produced a significant increase in the digestive utilization of protein. The additional fall in the levels of phytic acid caused by the addition of phytase did not lead to a subsequent improvement in the digestive utilization of protein. The mild hydrothermal treatment of pea flour produced a significant increase in the metabolic utilization of protein and carbohydrates, which was reflected in the protein efficiency ratio and food transformation growth indices. These effects were not observed in the phytase-supplemented pea diet.