Nutritional and Health-Related Effects of a Diet Containing Apple Seed Meal in Rats: The Case of Amygdalin.

Apple pomace includes seeds that are rich in protein, fiber, and oil, which can be extracted from them. However, they can also contain a significant amount of toxigenic amygdalin. We hypothesized that amygdalin is a compound that significantly reduces the nutritional and health quality of defatted apple seeds. An experiment was conducted on rats that were distributed into three groups and fed with high-fructose diets. In the control (C) and amygdalin (AMG) groups, cellulose and casein were the source of dietary fiber and protein, respectively; in the apple seed meal (ASM) group, dietary fiber and protein originated from the endosperm of apple seeds, which were previously defatted and ground. A diet fed to the ASM group also contained 0.24% of amygdalin from the meal, whereas the AMG diet was supplemented with the same amount of synthetic amygdalin. After 14 days of experimental feeding, the body weight of rats was decreased in the ASM group. When compared to the C group, apparent protein digestibility and nitrogen retention were increased in the AMG group, while both were decreased in the ASM group. In the small intestine, mucosal maltase activity was decreased in the AMG and ASM groups, whereas lactase activity was only decreased by dietary amygdalin. The caecal SCFA pool and butyrate concentration were significantly increased in the ASM group compared to the other groups. Moreover, the ASM diet increased plasma concentration of high density lipoprotein (HDL) cholesterol and plasma antioxidant capacity of water-soluble substances (ACW). It also decreased the liver content of thiobarbituric acid-reactive substances (TBARS). In contrast, dietary amygdalin did not affect these indices. Dietary supplementation with apple seed meal can exert beneficial effects on the intestinal tract, blood lipid profile and antioxidant status of rats. In most cases, these effects are not limited by the presence of amygdalin. However, the nutritional value of protein from apple seed meal is relatively low.

Effect of dietary supplementation with unprocessed and ethanol-extracted apple pomaces on caecal fermentation, antioxidant and blood biomarkers in rats.

The present 4-week study on growing Wistar rats was aimed at assessing the potential advantages of dietary supplementation with apple pomace containing both fibre and polyphenols, which enables nutritional exploitation of the physiological traits of both compounds. A total of twenty-four rats, assigned to the control (C), group fed with a diet supplemented with 14% of processed apple pomace (A) and group fed with a diet supplemented with 15% unprocessed apple pomace (AP) groups, were fed the following iso-fibrous diets: control, ethanol-extracted and unprocessed apple pomaces (low and high level of dietary polyphenols, i.e. 0·002 and 0·018%, respectively). To measure the animal response, parameters describing the caecal fermentation, antioxidative status and lipoprotein profile of rats were assessed. Both dietary apple pomaces were found to significantly (P≤0·05) decrease caecal pH and ammonia concentration, microbial ß-glucuronidase activity as well as to increase caecal SCFA concentration in comparison to the control diet. The unprocessed pomace did not suppress caecal fermentation. Unlike the extracted one, the dietary apple pomace rich in polyphenols significantly (P≤0·05 v. C group) increased erythrocyte superoxide dismutase activity and serum antioxidant capacity of lipid-soluble substances and significantly (P≤0·05 v. C group) decreased amounts of thiobarbituric acid-reactive substances in liver tissue. Moreover, the 4-week administration of the AP diet to rats evoked a significant decrease in serum glucose concentration (P≤0·05 v. C and A groups). In conclusion, the results demonstrated that the polyphenol-rich fibre complexes from apple pomace exerted positive effects on gastrointestinal physiology and antioxidant status of rats.

Caffeoylquinic acid-rich extract from chicory seeds improves glycemia, atherogenic index, and antioxidant status in rats.

OBJECTIVE: Comparison of the effects of a high-fructose diet supplemented with rutin, a phenolic compound with well-recognized bioavailability and bioactivity, and a chicory (Cichorium intybus L.) seed extract rich in caffeoylquinic acids (CQA) on gut physiology and the development of disorders related to metabolic syndrome. METHODS: A 28-d experiment was conducted on 32 young male Wistar rats. In comparison with control rats fed a standard corn starch diet (group C), the experimental group (group E) was fed a diet with an increased content of cholesterol and fructose (to 1% and 66% of the diet, respectively), as well as with oxidized soybean oil. Rats from the other two experimental groups were administered the same diet as group E during the first 2 wk of feeding, whereas at the beginning of the last 2 wk, the diet was enriched with rutin (group ER) or the CQA-rich ethanol extract from chicory seeds (9.6% of CQA, group EC), so the amount of added phenolics was equal in both dietary groups (0.15%). RESULTS: The diet administered in group E caused hyperglycemia and increased blood serum atherogenicity in rats, but did not induce other manifestations of the metabolic syndrome, i.e., dyslipidemia and oxidative stress. Additionally, it affected gut physiology through increasing mucosal sucrase activity and disturbing fermentative processes in the cecum, such as the production of short-chain fatty acids and the activity of microbial enzymes. Similarly to rutin, the dietary addition of the chicory seed extract improved glycemia, which was comparable to that determined in group C. In addition, the extract was found to decrease the atherogenic index to the level observed in group C and to increase blood antioxidant status. Both dietary supplements reduced the content of thiobarbituric acid-reactive substances in kidney and heart tissue when compared with group E. CONCLUSION: The potential efficacy of the CQA-rich extract from chicory seeds in improving diet-induced metabolic disturbances proved to be better than that of rutin; thus, the extract might be considered as a dietary supplement for carrying out clinical trials.

Polyphenol-rich strawberry pomace reduces serum and liver lipids and alters gastrointestinal metabolite formation in fructose-fed rats.

This study compared the effects of supplementation with a polyphenol-rich pomace from strawberry (US) and a strawberry pomace without most of these compounds (PS) on gastrointestinal, blood, and tissue biomarkers in rats fed diets differing in carbohydrate contents for 4 wk. The diets were: corn starch (group CS), high fructose (60% by weight; group F), starch with 7.7% of either US or PS (groups CS+US and CS+PS, respectively), and high fructose with 7.7% of either US or PS (groups F+US and F+PS, respectively). An interaction (P < 0.05) was observed between diet type and strawberry preparation, showing that upon fructose feeding, US had a greater effect than PS on lowering serum insulin, liver total cholesterol, and conjugated dienes. Additionally, the F+US group had lower serum FFA than the F+PS group (P < 0.05). The extraction of polyphenols diminished the physiological effect associated with strawberry intake, suggesting that the fiber component of the pomace was also active in reducing metabolic complications following fructose feeding to rats.

Physiological effects of chicory root preparations with various levels of fructan and polyphenolic fractions in diets for rats.

The experiment was aimed at studying the effects of easily fermentable oligosaccharides and phenolic compounds from chicory root meal (CRM) on the fermentative processes in the caecum, the antioxidative status and the lipoprotein profile of rats. Five different diets were fed ad libitum to 40 Wistar rats (eight animals per group, individually housed): a control group (C); group PCM (10% processed CRM, deprived of polyphenolic fraction); group PCMO (8% processed CRM and 1.6% oligofructose); group UCM (10% unprocessed CRM); and group FP (8.3% fructan-polyphenol concentrate from CRM). Diets PCM, PCMO, UCM and FP induced favourable metabolic changes in the caecum, blood lipid profile and the antioxidative status of the body. In the caecum, the experimental diets increased the production of volatile fatty acids (VFA) and acidification of digesta as well as a decrease in the ammonia concentration and bacterial beta-glucuronidase activity. In blood serum, the total cholesterol concentration was reduced and, simultaneously, the proportion of HDL in the total cholesterol concentration was increased. The presence of the polyphenolic fraction in the unprocessed meal (diets UCM and FP) evoked a significant increase in the total antioxidative status in blood serum. Dietary fibre and the polyphenolic fraction present in diet UCM and the FOS-polyphenol concentrate in diet FP did not exhibit an antagonistic activity regarding the physiological parameters analysed, except for in the intensity of caecal fermentation. The results of the experiment point to the benefits of dietary supplementation with chicory preparations containing both prebiotic saccharides and polyphenolic compounds, which enable us to take advantage of the physiological traits of both components.

Consumption of polyphenol concentrate with dietary fructo-oligosaccharides enhances cecal metabolism of quercetin glycosides in rats.

OBJECTIVE: We verified the hypothesis that the consumption of polyphenol concentrate (PC), rich in quercetin and its glycosides (36 g/100 g), in association with different dietary fiber matrices, that is, an easily fermentable fructo-oligosaccharides (FOS) or non-fermentable cellulose (CEL), causes a disparate adaptive response of the cecal microbial activity in rats. This in turn facilitates further utilization of biologically active polyphenolic compounds, which are not, as usual, digested in the foregut. METHODS: Four-week experimental feeding of male Wistar rats consisted of diets containing 5% FOS or CEL, as a source of dietary fiber, with or without 0.3% addition of PC. RESULTS: Positive changes in rat cecum were observed resulting from the ingestion of an FOS-containing diet, such as decreased pH and increased the production of short-chain fatty acids in the digesta, compared with a CEL-containing diet. The addition of PC to the FOS diet did not eliminate the positive effects of the latter, except for a slight increase in cecal pH and a decrease in microbial glycolytic activity. However, a simultaneous increase in the cecal butyrate pool was also observed. An adaptation process of the microflora enzymatic system to dieting with PC and FOS was proven in further enhanced susceptibility of rutin (quercetin 3-O-glucorhamnoside), hyperoside (quercetin 3-O-galactoside), and quercitrin (quercetin 3-O-rhamnoside) to hydrolysis by the cecal digesta solution. CONCLUSION: Especially when consumed together, PC and FOS are important dietary factors affecting the susceptibility of quercetin glycosides to microbial metabolism in the cecum. The intensification of the hydrolysis of quercetin glycosides by dietary treatments leads also to the increased metabolism of quercetin itself.

Effect of the dietary polyphenolic fraction of chicory root, peel, seed and leaf extracts on caecal fermentation and blood parameters in rats fed diets containing prebiotic fructans.

The aim of this 28 d experiment was to examine the physiological response of growing rats to a dietary combination of prebiotic chicory fructans, with polyphenols originating from different parts of the chicory plant, i.e. roots, root peels, seeds and leaves. A total of forty rats were assigned to groups fed the following diets characterised by a similar content of oligofructose and inulin: control, with 10 % of a root extract (a low level of dietary polyphenols, 0·05 %), with 6·5 % of a root peel extract (a medium level of dietary polyphenols, 0·107 %), with a combination of 8 % of a peel extract and 0·8 % of a seed extract (a high level of dietary polyphenols, 0·208 %) and with 2·5 % of a leaf extract (a medium level of dietary polyphenols, 0·106 %, with chicoric acid constituting half of them). Chicory seeds are the richest source of polyphenols, especially abundant in dicaffeoylquinic acids. When applied as a dietary supplement, the mixture of monocaffeoylquinic and dicaffeoylquinic acids, from the extracts made of roots, root peels and seeds, elicited more favourable changes in parameters of the antioxidative status of the body and in the activity of bacterial ß-glucuronidase in the faeces and caecal digesta. In turn, the extract from chicory leaves, containing considerable quantities of chicoric acid and polyphenolic glycosides, apart from chlorogenic acids, also triggered desirable changes in the lipid profile of the blood serum. The high concentration of polyphenols in the extracts examined enables their application as dietary supplements to be administered in low doses.

Uric acid but not apple polyphenols is responsible for the rise of plasma antioxidant activity after apple juice consumption in healthy subjects.

OBJECTIVE: To determine whether (1) rapid consumption of 1 L of apple juice increases blood antioxidant capacity, measured as ferric-reducing ability of plasma (FRAP) and serum 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, and (2) apple polyphenols or fructose-induced elevation of plasma uric acid contributes to post-juice increase of blood antioxidant activity. METHODS: The study involved 12 (mean age 32 ± 5 years, mean body weight 73 ± 7 kg) healthy nonsmoking subjects. Tested subjects consumed 1 L of clear apple juice and then FRAP; serum DPPH-scavenging activity, serum uric acid, and total plasma phenolics and quercetin levels were measured just before juice ingestion and 1, 2.5, and 4 hours after ingestion. This was repeated 3 times with 4-day intervals, but volunteers drank either 1 L of clear apple juice without polyphenols (placebo), or 1 L of cloudy apple juice (positive control), or 1 L of water (negative control) at the time. All juices had similar content of sugars (i.e., saccharose, glucose, and fructose) and precisely defined composition of phenolics and antioxidant activity. RESULTS: Consumption of all 3 juices transiently increased FRAP and serum DPPH-scavenging activity, with peak values at 1 hour post-juice ingestion. This was paralleled by the rise of serum uric acid, but no significant changes in plasma total phenolics and quercetin levels were observed after all dietary interventions. At the same time, no substantial differences were found between juices (especially between clear apple juice and clear apple juice without polyphenols) concerning the measured variables. A strong significant correlation was noted instead between serum uric acid and plasma antioxidant activity at all analyzed time points, before and after juice ingestion. Plasma total phenolics and quercetin levels were not associated with FRAP and serum DPPH radical-scavenging activity. CONCLUSIONS: We have demonstrated that rapid consumption of apple juice increased plasma antioxidant activity in healthy subjects; this was caused by the fructose-induced rise of serum uric acid levels, but was not due to the presence of antioxidant polyphenols in juice. Thus, short-term consumption of apple juice seems not to be the effective dietary intervention to augment plasma antioxidant activity due to the concomitant possibility for uric acid to be a risk factor for several diseases, as verified by other authors.

Gastrointestinal tract metabolism of young turkeys fed diets supplemented with pure nystose or a fructooligosaccharide mixture.

In a four-week experiment on 60 7-day-old BUT-9 male turkeys the effects of dietary fructooligosaccharides (pure nystose and a fructooligosaccharide mixture) supplemented at 1 and 2%, were studied on ileal and caecal metabolism. The control carbohydrate was cellulose, added also at 1 or 2%. Each dietary treatment consists of 10 birds kept individually. The average degree of polymerisation of the nystose and oligofructose preparation amounted to 2.9 and 4.1, respectively. The addition of nystose significantly decreased the pH value and viscosity in the ileal contents compared with the cellulose treatment. On the other hand, the oligofructose preparation increased the activity of sucrase and lactase in the ileal mucosal by 30-60% and 33-47%, respectively. Both fructan preparations similarly acidified the caecal and colonic digesta (by 0.2-0.4 pH units) as well as diminished the activity of bacterial harmful beta-glucuronidase (by 24-40%), but only nystose caused an enlargement of the caeca and effectively reduced caecal ammonia concentration, especially at a higher dose. Oligofructose supplementation at 2% caused a 3.5-fold increase of bacterial activity of alph- and beta-galactosidase, while 2% nystose resulted in 1.7 and 3 times higher alpha- and beta-glucosidases activities, respectively. Compared to oligofructose, dietary nystose increased propionic and decreased butyric fermentation in caeca. Nystose and oligofructose preparations added at 2% reduced the triacylglycerol concentration in the serum in comparison to the addition of 2% cellulose by 46 and 25%, respectively. Beside the fact that dietary levels of supplementation were of great importance, the results indicated that even small difference in the length of carbohydrate chain may cause different physiological responses.

[Black currant seeds after supercritical carbon dioxide extraction as a potential dietary supplement]. / Nasiona porzeczki czarnej po ekstrakcji nadkrytycznej ditlenkiem wegla jako potencjalny suplement diety.

The aim of this study was to estimate the physiological effects of black currant seeds after supercritical carbon dioxide extraction on the gastrointestinal tract and metabolism of rats used as an experimental model. The preparation contained 25% of total protein, 57.9% of dietary fiber and 4% of fat. Young Wistar rats divided into two experimental groups of 10 animals each, were fed for 28 days using semi-purified casein diets with a high fructose content (69%). The diets contained the same amount of protein and fiber. An inclusion of the tested seeds to the diet (10% as expense of cellulose, corn starch and part of casein) lowered the activity of glycolytic enzymes in the mucosa of the small intestine, whereas intestinal microflora elevated its glycolytic activity, and in consequence, increased production of short-chain fatty acids in the caecum. A distinct hypoglycemic actions of the tested preparation were also observed, while its antioxidant properties were found to be rather low and expressed by the decreased content of thiobarbituric acid-reactive substances in the kidney tissue.

Ferric-reducing ability power of selected plant polyphenols and their metabolites: implications for clinical studies on the antioxidant effects of fruits and vegetable consumption.

Undeniably, low sensitivities in the ferric-reducing ability power (FRAP) is evident in the detection of the augmentation of plasma antioxidant activity, relative to the rise in circulating polyphenols after ingestion of fruits and vegetables. We investigated in vitro the FRAP of 17 plant polyphenols and their metabolites at submicromolar concentrations commensurate in human plasma. We then explored the in vitro effects of polyphenols and purified apple quercetin glycosides on plasma FRAP. We found that apple quercetin glycosides along with various polyphenols observed this distinct power at submicromolar concentrations. The presence of a catechol structure in the compound molecule was positively associated with FRAP (r = 0.60, P < 0.05). An aliphatic substitute at a catechol ring and a double bond in an aliphatic substitute conjugated with an aromatic ring of catechol contributed to 37% of the variance in the FRAP of compounds with catechol in the backbone structure (n = 11). Plasma supplementation with 0.2 microM mixtures of seven of the most active compounds (catechin, 3,4-dihydroxycinnamic acid, 3,4-dihydroxyhydrocinnamic acid, 3,4-dihydroxyphenylacetic acid, ferulic acid, gallic acid and quercetin) initiated a placid rise in FRAP (23.3 +/- 1.2 versus 28.1 +/- 1.3 nmol of Fe(3+), P < 0.05). Apple quercetin glycosides at 0.5 microM did not elevate plasma FRAP. Plasma alone had 30 times higher power than quercetin glycosides at 0.5 microM. Abounding of FRAP exhibited in human plasma as compared to polyphenols at submicromolar concentrations, may offer elucidation to previous incongruities implicated in insignificant rises of plasma FRAP several days after ingestion of fruits or vegetables. This suggests that intake of food products and/or supplements rich in polyphenols containing a catechol ring with an aliphatic substitute augments the plasma FRAP in human beings.

Biological properties of fructooligosaccharides with different contents of kestose and nystose in rats.

In a four-week experiment on rats' diets containing 5% of sucrose or fructooligosaccharides (FOS) diversified in terms of kestose and nystose contents: 6:1 (FOS-K), 3:1 (FOS-KN), and 0.5:1 (FOS-N) were applied. All FOS preparations, primarily FOS-N, considerably increased the mass of caecum, lowered pH of caecal digesta, and increased concentrations of protein. The glycolytic activity of the caecal digesta was generally alike in all groups, except for the control group where the activity of beta-glucosidase was negligibly lower and that of alpha-galactosidase higher. The administration of FOS preparation with a diet increased the concentration and the pool of total VFA in the caecal digesta, especially in the case of butyric and propionic acids and decreased the concentration of iso-butyric and valeric acids. When compared with the kestose-rich preparation, the nystose-rich preparation increased the production of total VFA in the caecum, primarily of n-butyrate and propionate. Different length of kestose and nystose chains had no effect on the activity of bacterial enzymes in the caecum nor the biochemical indices of serum, concentration of cholesterol, glucose, urea, Ca, P and Mg.