Cholesterol Response and Foam Cell Formation in Hamsters Fed Rice Bran,Oat Bran,and Cellulose + Soy Protein Diets With or Without Added Vitamin E

Four-week-old male golden Syrian hamsters were fed diets containing cellulose (control, CC), cellulose + soy protein (CS), CS + vitamin E, (CSE), rice bran (RB), RB + vitamin E (RBE), oat bran (OB), and OB + vitamin E (OBE) for six weeks (n = 10/treatment). Diets contained (by weight) 10% total dietary fiber, 3% N, 20% fat, 0.5% cholesterol, and some diets had an additional 0.1% vitamin E. After six weeks, RB and OB diets resulted in significantly higher weight gain than the CC diet. Plasma low-density lipoprotein cholesterol (LDL-C) values and the LDL-C/high-density lipoprotein cholesterol ratio in hamsters fed CSE, RBE, OB, and OBE diets were significantly lower than in those fed CC diet. There were no significant differences in total plasma cholesterol values among the hamsters fed any of the diets. Liver cholesterol in animals fed OB and OBE diets was significantly lower than in all other groups. Foam cell areas in the inner bend of the aortic arch in animals fed all treatment diets were significantly reduced when compared with that in animals fed CC diet. The level of additional dietary vitamin E did not result in further significant reductions in foam cell area. The results of this study suggest that diets containing rice bran, oat bran, or soy protein significantly reduced the development of atherosclerosis in hypercholesterolemic hamsters.     

Investigation on the lipid- and cholesterol-lowering abilities of biocellulose.

The present study investigated and compared the physicochemical properties as well as the hypolipidemic and hypocholesterolemic effects between plant cellulose and biocellulose. Biocellulose had higher water-holding and cation-exchange capacities than plant cellulose ( approximately 2- and 6-fold, respectively). The results showed that the administration of plant cellulose and biocellulose to hamsters effectively ( P < 0.05) decreased the concentrations of serum triglyceride (by 13.9-55.5%), serum total cholesterol (by 17.4-27.9%), serum low-density lipoprotein cholesterol (by 41.9-47.9%), liver total lipids (by 6.4-10.3%), and liver cholesterol (by 11.8-16.3%). Feeding plant cellulose and biocellulose also enhanced the excretion of total lipids (144-182%), cholesterol (136-203%), and bile acids (259-479%) in feces. The efficacy of biocellulose in lowering serum lipids and cholesterol in hamsters was significantly higher than that of plant cellulose. These results suggested that biocellulose could be a promising low-calorie bulking ingredient for the development of novel fiber-rich functional foods of different forms such as powder, gelatinous, or shred forms.     

Effects of xylanase treatments on gelling and water-uptaking properties of psyllium

The effects of a commercial food-grade xylanase on the physicochemical properties of psyllium were evaluated. The enzymatic reactions were conducted in solid state at ambient temperature. The enzyme-treated psyllium preparations were analyzed and compared with the starting psyllium for their water-uptake properties, gelling capacities, soluble and insoluble fiber contents, and surface structures. The solid-state xylanase treatment significantly reduced both water-uptake and gelling capacities of psyllium (p < 0.01), with a slight decrease of soluble fiber content, whereas no effect on insoluble fiber content was observed. The xylanase treatment also resulted in a smoother surface structure of psyllium particles. In addition, no special equipment and operation were required to conduct the enzymatic reaction, which generated no waste. These data indicated a potential to improve the physicochemical properties of psyllium by use of the solid-state xylanase reactions to promote the utilization of psyllium fiber in functional foods for promoting human health.     

Lipidemic Response of Hamsters to Rice Bran,Uncooked or Processed White and Brown Rice,and Processed Corn Starch

This study was undertaken to evaluate the lipidemic response of rice bran and the possible enhancement of its healthful properties by using raw or processed white or brown rice in place of corn starch. All diets contained 10% total dietary fiber, 15% fat, and 0.5% cholesterol. Weanling male golden Syrian hamsters were fed cellulose control (CC), processed corn starch (PCS), cellulose with processed brown rice (CPBR), rice bran (RB), RB with white rice (RBWR), RB with processed white rice (RBPWR), RB with brown rice (RBBR), and RB with processed brown rice (RBPBR) diets. After three weeks, the PCS diet significantly lowered total plasma cholesterol (TC) compared with the CC, CPBR, RBWR, and RBPBR diets. RB and RBBR diets significantly lowered TC and LDL‐C compared with CPBR diet. All the RB‐containing and PCS diets significantly lowered liver cholesterol and liver lipid content. Processing white rice increased TDF content 240% and insoluble dietary fiber (IDF) 360%, whereas soluble dietary fiber (SDF) decreased by 25%. Uncooked brown rice contained 7 times as much TDF as uncooked white rice. Processing brown rice decreased its TDF, IDF and SDF contents by 12, 6, and 42%, respectively. The data suggest that a possible mechanism for cholesterol‐lowering by rice bran, with or without added raw or processed rice (white or brown), is by decreasing lipid digestibility and increasing neutral sterol excretion, whereas cholesterol‐lowering by processed corn starch is mediated through other mechanisms.     

Hypolipidemic effects and absorption of citrus polymethoxylated flavones in hamsters with diet-induced hypercholesterolemia

Formulations containing citrus polymethoxylated flavones (PMFs), mainly tangeretin, or citrus flavanone glucosides, hesperidin and naringin, were evaluated for cholesterol-lowering potential in hamsters with diet-induced hypercholesterolemia. PMF metabolites were also investigated. Diets containing 1% PMFs significantly reduced serum total and very low-density lipoprotein (VLDL) + LDL cholesterol (by 19-27 and 32-40%, respectively) and either reduced or tended to reduce serum triacylglycerols. Comparable reductions were achieved by feeding a 3% mixture of hesperidin and naringin (1:1, w/w), implying lower hypolipidemic potency of the hesperidin/naringin vs PMFs. HPLC-MS analysis identified high serum, liver, and urine concentrations of tangeretin metabolites including dihydroxytrimethoxyflavone and monohydroxytetramethoxyflavone glucuronides and aglycones. Total liver concentrations of tangeretin derivatives corresponded to hypolipidemic concentrations of intact tangeretin in earlier experiments in vitro. This suggests that PMFs are novel flavonoids with cholesterol- and triacylglycerol-lowering potential and that elevated levels of PMF metabolites in the liver might be directly responsible for their hypolipidemic effects in vivo.     

Effect of Extrusion on Hypocholesterolemic Properties of Rice,Oat, Corn,and Wheat Bran Diets in Hamsters

Brans from rice, oats, corn, and wheat were cooked in a twin-screw extruder at either high or low energy input, and their cholesterol-lowering effects were compared with those of unprocessed brans when fed to four-week-old male golden Syrian hamsters (n = 10 per treatment) for three weeks. Peanut oil was added to oat, corn, and wheat bran during the extrusion process to match the oil content of rice bran. Diets contained 10% total dietary fiber, 10.3% fat, 3% nitrogen, and 0.3% cholesterol. Plasma and liver cholesterol and total liver lipids were significantly lower with low-energy extruded wheat bran compared with unprocessed wheat bran. Extrusion did not alter the hypocholesterolemic effects of rice, oat, or corn brans. Plasma and liver cholesterol levels with corn bran were similar to those with oat bran. Relative cholesterol-lowering effects of the brans, determined with pooled (extruded and unextruded) bran data, were rice bran > oat bran > corn bran > wheat bran. Rice bran diets resulted in significantly lower levels of total plasma cholesterol and very low density lipoprotein cholesterol compared with all other brans. Total liver cholesterol and liver cholesterol concentrations (mg/g) were significantly lower with high-energy extruded rice bran compared with the cellulose control group. Plasma cholesterol and total liver cholesterol values with low-energy extruded wheat bran were similar to those with rice bran (unextruded or extruded) diets. Lowered cholesterol with rice bran diets may result in part from greater lipid and sterol excretion with these diets. Results with low-energy extruded wheat bran suggest that this type of processing may improve the potential for lowering cholesterol with wheat bran products.     

Effects of long-term feeding of chitosan on postprandial lipid responses and lipid metabolism in a high-sucrose-diet-impaired glucose-tolerant rat model

This study was designed to investigate the effects of long-term feeding of chitosan on postprandial lipid response and lipid metabolism in a high-sucrose (HS)-diet-impaired glucose-tolerant rat model. As the results, HS-diet-fed rats supplemented with 5 and 7% chitosan in diets for 9 weeks had lower postprandial plasma total cholesterol (TC) levels, but 7% chitosan in the diet had higher postprandial plasma triglyceride (TG) and TG-rich lipoprotein TG levels. Supplementation of chitosan significantly decreased the postprandial ratio of apolipoprotein B (apoB)48/apoB100 in TG-rich lipoprotein fractions of HS-diet-fed rats. Long-term supplementation of 5 and 7% chitosan in diets for 16 weeks had lower plasma TC, low-density lipoprotein cholesterol (LDL-C) + very low density lipoprotein cholesterol (VLDL-C), TC/high-density lipoprotein (HDL-C) ratio, leptin, and tumor necrosis factor-α (TNF-α) levels in HS-diet-fed rats. Moreover, it was noticed that the VLDL receptor (VLDLR) protein expression in skeletal muscles of HS-diet-fed rats was significantly decreased, which could be significantly reversed by supplementation of 5 and 7% chitosan. Rats supplemented with 7% chitosan in the diet significantly elevated the lipolysis rate and decreased the accumulation of TG in epididymal fat pads of HS-diet-fed rats. The plasma angiopoietin-like 4 (ANGPTL4) protein expression was not affected in HS-diet-fed rats, but it was significantly increased in 7% chitosan-supplemented HS-diet-fed rats. Taken together, these results indicate that supplementation of chitosan in the diet can improve the impairment of lipid metabolism in a HS-diet-fed rat model, but long-term high-dose chitosan feeding may enhance postprandial plasma TG and TG-rich lipoprotein TG levels in HS-diet-fed rats through an ANGPTL4-regulated pathway.     

Comparative studies on the hypolipidemic and growth suppressive effects of oolong, black, pu-erh, and green tea leaves in rats

The four major commercial teas, oolong, black, pu-erh, and green teas, have been manufactured in southeast Asia. In this study, we evaluated the growth suppressive and hypolipidemic effect of these four different tea leaves by oral feeding to male Sprague-Dawley rats for 30 weeks. The results showed that the suppression of body weights of tea leaves-fed groups were in the order: oolong tea > pu-erh tea > black tea > green tea. Pu-erh tea and oolong tea could lower the levels of triglyceride more significantly than that of green tea and black tea, but pu-erh tea and green tea were more efficient than oolong tea and black tea in lowering the level of total cholesterol. In lipoprotein, 4% pu-erh tea could increase the level of HDL-C and decrease the level of LDL-C, but other teas simply decrease the levels of both. The activity of antioxidant enzyme SOD is increased in all tea-fed groups as compared to the basal diet-fed group. Finally, relative weight ratios of liver to epididylmal adipose tissue were lower in feeding oolong tea and pu-erh tea groups. On the basis of these findings, it seemed that the fully fermented pu-erh and black tea leaves and partially fermented oolong tea leaves were more effective on their growth suppressive and hypolipidemic effects as compared to the nonfermented green tea leaves.     

Extrusion Conditions Modify Hypocholesterolemic Properties of Wheat Bran Fed to Hamsters

Wheat bran was extruded in a twin‐screw extruder at five specific mechanical energy (SME) levels (0.120, 0.177, 0.234, 0.291, and 0.358 kWh/kg, dwb) and the cholesterol‐lowering effects were compared with those of unprocessed wheat bran when fed to four‐week‐old male golden Syrian hamsters (n = 10/treatment) for three weeks. Diets contained 10% total dietary fiber, 10.3% fat, 3% nitrogen, and 0.4% cholesterol. Plasma total cholesterol and very‐low‐density lipoprotein cholesterol were significantly lower with 0.120 kWh/kg extruded wheat bran diet compared with the unextruded wheat bran control. Total triglycerides were significantly lower with 0.120 and 0.177 kWh/kg wheat bran diets compared with those fed 0.291 and 0.358 kWh/kg extruded wheat bran diets. Cholesterol digestibility, total liver cholesterol, and total liver lipids were significantly lower with all the extruded wheat bran diets compared with the unextruded wheat bran control. Cholesterol digestibility for the 0.291 kWh/kg wheat bran diet was also significantly lower than all other extruded diets. Significantly more sterols were excreted with diets containing 0.291 and 0.358 kWh/kg extruded wheat bran compared with the unextruded wheat bran control. Wheat bran extruded with 0.291 kWh/kg diet resulted in a 13% reduction in plasma cholesterol and a 29% reduction in low‐density lipoprotein cholesterol. Considering lowest cholesterol digestibility, significantly higher sterol excretion, desirable plasma lipo‐protein cholesterol profile, significantly lower liver weight, total liver lipids, and liver cholesterol, the wheat bran extruded at 0.291 kWh/kg appeared to have the most desirable healthful potential. Data suggest that cholesterol‐lowering potential of wheat bran could be enhanced by optimizing the energy input used in the extrusion process.     

Nutritional effects of enzymatically modified soybean oil with caprylic acid versus physical mixture analogue in obese Zucker rats

Enzymatically modified soybean oil with caprylic acid (SL), a physical mixture of tricaprylin and soybean oil (PHY), and soybean oil as control were fed (20% of diet weight) to female obese Zucker rats. Both lipids (SL and PHY) have similar total fatty acid composition containing 23.4 mol % caprylic acid (C8:0) but have different lipid structures. After 21 days of feeding, the body weight gain was 36.4% in the SL-fed group and 35.2% in the PHY-fed group, respectively; whereas the body weight of the control group increased 41.6%. Significant differences in the respiratory exchange ratio were observed between the SL and PHY groups. However, the contents of glucose, total and high density lipoprotein (HDL) cholesterol, and very low density and low density lipoprotein (VLDL + LDL) cholesterol in serum were not significantly different between the SL- and PHY-fed groups or among the three dietary groups (control, SL, and PHY) (p < 0.05). On the other hand, plasma total cholesterol and plasma triacylglycerol (TAG) were significantly higher in SL- and PHY-fed groups than in the control group. In the liver and inguinal adipocyte TAG, C8:0 was found in the SL-fed group, whereas it was not observed in the liver and inguinal adipocyte TAG of the PHY-fed group, which suggests that positional distribution of C8:0 of the TAG molecule is an important consideration in the metabolism of lipids. This study showed that different positional distribution in TAG molecules lead to different metabolic fates, resulting in the change of fatty acid composition in liver and inguinal adipose TAG in female Zucker rats.     

Effects of solid-state yeast treatment on the antioxidant properties and protein and fiber compositions of common hard wheat bran

The bran fraction of wheat grain is known to contain significant quantities of bioactive components. This study evaluated the potential of solid-state yeast fermentation to improve the health beneficial properties of wheat bran, including extractable antioxidant properties, protein contents, and soluble and insoluble fiber compositions. Three commercial food grade yeast preparations were evaluated in the study along with the effects of yeast dose, treatment time, and their interaction with the beneficial components. Solid-state yeast treatments were able to significantly increase releasable antioxidant properties ranging from 28 to 65, from 0 to 20, from 13 to 19, from 0 to 25, from 50 to 100, and from 3 to 333% for scavenging capacities against peroxyl (ORAC), ABTS cation, DPPH and hydroxyl radicals, total phenolic contents (TPC), and phenolic acids, respectively. Yeast treatment increased protein content 11-12% but did not significantly alter the fiber composition of wheat bran. Effects of solid-state yeast treatment on both ORAC and TPC of wheat bran were altered by yeast dose, treatment time, and their interaction. Results suggest that solid-state yeast treatment may be a commercially viable postharvest procedure for improving the health beneficial properties of wheat bran and other wheat-based food ingredients.     

Optimization of bioactive compounds in buckwheat sprouts and their effect on blood cholesterol in hamsters

Nutrient levels in buckwheats that were maximized in day 8 sprouts (D8SP) included total phenolics, quercetin, and l-ascorbic acid, whereas those of oxalic, malic, tartaric, and citric acids, rutin, and gamma-aminobutyric acid (GABA) were found to reach maximum levels on day 10. Ethanolic extract of D8SP (2.5 mg/mL) revealed potent free-radical scavenging (FRS) and antioxidative (ANO) capabilities. However, its Fe2+-chelating capability was only moderate. To further study the hypolipidemic activity of D8SP, 36 Syrian hamsters were grouped into six groups and fed for 28 days, respectively, with (i) control meal, (ii) high fat plus high cholesterol meal, (iii) high fat plus high cholesterol plus 2.5% of buckwheat seeds, (iv) high fat plus high cholesterol plus 25% of buckwheat seeds, (v) high fat plus high cholesterol plus 2.5% of D8SP, and (vi) high fat plus high cholesterol plus 25% of D8SP. High seed meal prominently enhanced body weight gain, whereas high sprout meal exhibited the highest feed efficiency. Ratios of liver/body weight (L/B) were significantly lowered by all BS meals. Although low seed meal reduced serum total cholesterol (TC) levels (p<0.05), its effect was still inferior to the high seed and sprout meals (p<0.01). In contrast, serum triglyceride (TG) levels were lowered only by the high seed and sprout meals (p<0.05). Alternatively, levels of serum low-density lipoprotein cholesterol (LDL-C) were significantly suppressed by all buckwheat meals (p<0.01). Serum high-density lipoprotein cholesterol (HDL-C) levels were increased, however, insignificantly. Nutraceutically more meaningful is that both LDL-C/HDL-C and TC/HDL-C ratios were significantly lowered (p<0.01). Apparently, hepatic TC levels were significantly reduced, whereas hepatic TG levels were totally unaffected. Conclusively, sprouting triggers a variety of nutritional changes in buckwheats. Day 8 sprouts, consisting of high polyphenolic and moderate quercetin contents, are nutraceutically maximized when hypocholesterolemic, hypotriglyceridemic, and antioxidative activities are concerned.     

Supplementation of hydroxypropyl methylcellulose into yeast leavened all-whole grain barley bread potentiates cholesterol-lowering effect

We investigated in Syrian Golden hamsters the biological impact and its underlying mechanism of single whole grain breads supplemented with 2-3% hydroxypropyl methylcellulose (HPMC), a semisynthetic viscous soluble dietary fiber (SDF) as a substitute for gluten. Hamsters were fed high-fat diets supplemented with 48-65% (w/w) differently ground, freeze-dried single grain breads including whole grain wheat, barley, barley supplemented with HPMC, debranned oat, and oat supplemented with HPMC which were compared to a diet containing microcrystalline cellulose (control). All single grain breads significantly lowered plasma LDL-cholesterol concentrations compared to the control. Enrichment with HPMC further lowered plasma and hepatic cholesterol concentrations. Despite the reduced molecular weight of naturally occurring soluble (1--->3),(1--->4)-β-d-glucan (β-glucan) caused by the bread-making process, whole grain barley breads downregulated hepatic expression of CYP7A1 and HMG-CoAR genes that are responsible for bile acid and cholesterol synthesis, suggesting a possible role of bioactive compounds such as short-chain fatty acids and phenolic compounds from barley bread. Barley bread enriched with HPMC downregulated expression of ABCG5 gene. Taken together, it appears that distinctive modulation of synthesis and excretion of hepatic cholesterol and bile acid contributes to the cholesterol-lowering properties of whole grain barley breads and breads enriched with HPMC. These data suggests that alternative whole grain breads supplemented with HPMC may provide consumers with a staple food that can assist in cholesterol management.     

Pterostilbene, a new agonist for the peroxisome proliferator-activated receptor alpha-isoform, lowers plasma lipoproteins and cholesterol in hypercholesterolemic hamsters

Resveratrol, a stilbenoid antioxidant found in grapes, wine, peanuts and other berries, has been reported to have hypolipidemic properties. We investigated whether resveratrol and its three analogues (pterostilbene, piceatannol, and resveratrol trimethyl ether) would activate the peroxisome proliferator-activated receptor alpha (PPARalpha) isoform. This nuclear receptor is proposed to mediate the activity of lipid-lowering drugs such as the fibrates. The four stilbenes were evaluated at 1, 10, 100, and 300 microM along with ciprofibrate (positive control), for the activation of endogenous PPARalpha in H4IIEC3 cells. Cells were transfected with a peroxisome proliferator response element-AB (rat fatty acyl CoA beta-oxidase response element)-luciferase gene reporter construct. Pterostilbene demonstrated the highest induction of PPARalpha showing 8- and 14-fold increases in luciferase activity at 100 and 300 microM, respectively, relative to the control. The maximal luciferase activity responses to pterostilbene were higher than those obtained with the hypolipidemic drug, ciprofibrate (33910 and 19460 relative luciferase units, respectively), at 100 microM. Hypercholesterolemic hamsters fed with pterostilbene at 25 ppm of the diet showed 29% lower plasma low density lipoprotein (LDL) cholesterol, 7% higher plasma high density lipoprotein (HDL) cholesterol, and 14% lower plasma glucose as compared to the control group. The LDL/HDL ratio was also statistically significantly lower for pterostilbene, as compared to results for the control animals, at this diet concentration. Results from in vitro studies showed that pterostilbene acts as a PPARalpha agonist and may be a more effective PPARalpha agonist and hypolipidemic agent than resveratrol. In vivo studies demonstrate that pterostilbene possesses lipid and glucose lowering effects.     

In vitro fermentation of arabinoxylan oligosaccharides and low molecular mass arabinoxylans with different structural properties from wheat (Triticum aestivum L.) bran and psyllium (Plantago ovata Forsk) seed husk

Ball milling was used for producing complex arabinoxylan oligosaccharides (AXOS) and low molecular mass arabinoxylans (AX) from wheat bran, pericarp-enriched wheat bran, and psyllium seed husk. The arabinose to xylose ratio of the samples produced varied between 0.14 and 0.92, and their average degree of polymerization (avDP) ranged between 42 and 300. Their fermentation for 48 h in an in vitro system using human colon suspensions was compared to enzymatically produced wheat bran AXOS with an arabinose to xylose ratio of 0.22 and 0.34 and an avDP of 4 and 40, respectively. Degrees of AXOS fermentation ranged from 28% to 50% and were lower for the higher arabinose to xylose ratio and/or higher avDP materials. Arabinose to xylose ratios of the unfermented fractions exceeded those of their fermented counterparts, indicating that molecules less substituted with arabinose were preferably fermented. Xylanase, arabinofuranosidase, and xylosidase activities increased with incubation time. Enzyme activities in the samples containing psyllium seed husk AX or psyllium seed husk AXOS were generally higher than those in the wheat bran AXOS preparations. Fermentation gave rise to unbranched short-chain fatty acids. Concentrations of acetic, propionic, and butyric acids increased to 1.9-2.6, 1.9-2.8, and 1.3-2.0 times their initial values, respectively, after 24 h incubation. Results show that the human intestinal microbiota can at least partially use complex AXOS and low molecular mass AX. The tested materials are thus interesting physiologically active carbohydrates.     

Whole berries versus berry anthocyanins: interactions with dietary fat levels in the C57BL/6J mouse model of obesity

Male C57BL/6J mice received diets with either 10% of calories from fat (LF) or a high-fat diet [45% (HF45) or 60% (HF60) calories from fat] for 92 days (expt 1) or 70 days (expt 2). These were given with or without freeze-dried powders from whole blueberries (BB) or strawberries (SB) (expt 1) or purified anthocyanin extracts from BB or SB (expt 2). Body composition was determined utilizing Echo MRI. Berries added to the LF diet did not alter weight gain, final body weights, body fat, or protein (percent body weight) or diet (grams) or energy (kilocalories) intake. However, in both HF45- and HF60-fed mice, weight gain, final weights, body fat (percent), and epididymal fat weights increased and body protein decreased ( p < 0.01) compared to LF mice. In mice fed HF45 diet plus BB, body weight gains, body fat (percent of BW), and epididymal fat weights were significantly greater than those in the HF45-fed controls, whereas weights of mice fed SB HF were similar to those of HF controls. SB or BB feeding did not alter glucose tolerance, although glucose tolerance decreased with age and in HF45 versus LF mice. Baseline plasma glucose was lower in SB- versus HF45-fed mice. After 8 weeks, mice fed the HF60 diet plus purified anthocyanins from BB in the drinking water had lower body weight gains and body fat than the HF60-fed controls. Anthocyanins fed as the whole blueberry did not prevent and may have actually increased obesity. However, feeding purified anthocyanins from blueberries or strawberries reduced obesity.     

Low-dose fish oil consumption prevents hepatic lipid accumulation in high cholesterol diet fed mice

We examined the effects of low-dose fish oil ingestion on hepatic lipid accumulation caused after high cholesterol feeding in C57BL/6J mice. The mice were fed purified experimental diets consisting of 20 energy % (en%) safflower oil (SO or SO/CH), 2 en% fish oil + 18 en% safflower oil (2FO or 2FO/CH), or 5 en% fish oil + 15 en% safflower oil (5FO or 5FO/CH) with or without 2 weight % (wt %) cholesterol for 8 weeks. Hepatic triglyceride and total cholesterol contents were significantly lower in groups that were fed diets containing fish oil and cholesterol than in those that were fed safflower oil and cholesterol. The hepatic mRNA levels of fatty acid synthase (FAS) were lower in groups fed cholesterol or fish oil. Fatty acid oxidation-related hepatic gene expressions were higher in fish oil-fed groups. Fecal cholesterol excretion was higher in all cholesterol-fed groups; cholesterol excretion was high in groups fed fish oil and cholesterol. These results suggest that low-dose fish oil diets improve lipid metabolism by modifying the expression of lipid metabolism-related genes in the liver and increasing fecal cholesterol excretion.     

Olive oils improve lipid metabolism and increase antioxidant potential in rats fed diets containing cholesterol

The effect of olive oils on lipid metabolism and antioxidant activity was investigated on 60 male Wistar rats adapted to cholesterol-free or 1% cholesterol diets. The rats were divided into six diet groups of 10. The control group (control) consumed the basal diet (BD) only, which contained wheat starch, casein, cellulose, and mineral and vitamin mixtures. To the BD were added 10 g/100 g virgin (virg group) or Lampante (Lamp group) oils, 1 g/100 g cholesterol (chol group), or both (chol/virg group) and (chol/Lamp group). The experiment lasted 4 weeks. Plasma total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglycerides (TG), total phospholipids (TPH), HDL-phospholipids (HDL-PH), total radical-trapping antioxidative potential (TRAP), malondialdehyde lipid peroxidation (MDA), and liver TC were measured. Groups did not differ before the experiment. In the chol/virg and chol/Lamp vs chol group, the oil-supplemented diets significantly (P < 0.05) lessened the increase in plasma lipids due to dietary cholesterol as follows: TC (25.1 and 23.6%), LDL-C (39.3 and 34.7%), TG (19.3 and 17.0%), and TC in liver (36.0 and 35.1%) for the chol/virg and chol/Lamp group, respectively. The chol/virg and chol/Lamp diets significantly decreased the levels of TPH (24.7 and 21.2%; p < 0.05 in both cases) and HDL-PH (22.9 and 18.0%; p < 0.05 in both cases) for the chol/virg and chol/Lamp group, respectively. Virgin and Lampante oils in rats fed basal diet without cholesterol did not affect the lipid variables measured. Virgin, and to a lesser degree Lampante, oils have increased the plasma antioxidant activity in rats fed BD without cholesterol (an increase in TRAP, 20.6 and 18.5%; and a decrease in MDA, 23.2 and 11.3%, respectively). In the rats of chol/virg and chol/Lamp vs Chol diet groups the added oils significantly hindered the decrease in the plasma antioxidant activity (TRAP, 21.2 and 16.7%; and MDA, 27.0 and 22.3%, respectively). These results demonstrate that virgin, and to less degree Lampante, oils possess hypolipidemic and antioxidant properties. It is more evident when these oils are added to the diets of rats fed cholesterol. These positive properties are attributed mostly to the phenolic compounds of the studied oils.     

Lower weight gain and hepatic lipid content in hamsters fed high fat diets supplemented with white rice protein, brown rice protein, soy protein, and their hydrolysates

The physiological effects of the hydrolysates of white rice protein (WRP), brown rice protein (BRP), and soy protein (SP) hydrolyzed by the food grade enzyme, alcalase2.4 L, were compared to the original protein source. Male Syrian Golden hamsters were fed high-fat diets containing either 20% casein (control) or 20% extracted proteins or their hydrolysates as the protein source for 3 weeks. The brown rice protein hydrolysate (BRPH) diet group reduced weight gain 76% compared with the control. Animals fed the BRPH supplemented diet also had lower final body weight, liver weight, very low density lipoprotein cholesterol (VLDL-C), and liver cholesterol, and higher fecal fat and bile acid excretion than the control. Expression levels of hepatic genes for lipid oxidation, PPARα, ACOX1, and CPT1, were highest for hamsters fed the BRPH supplemented diet. Expression of CYP7A1, the gene regulating bile acid synthesis, was higher in all test groups. Expression of CYP51, a gene coding for an enzyme involved in cholesterol synthesis, was highest in the BRPH diet group. The results suggest that BRPH includes unique peptides that reduce weight gain and hepatic cholesterol synthesis.     

Effect of Wheat Bran Fiber and Bran Particle Size on Fat and Fiber Digestibility and Gastrointestinal Tract Measurements in the Rat

The effect of wheat bran (AACC hard red) and bran particle size on fat and fiber digestibility and gastrointestinal tract measurements were investigated with diets containing 5.7–10.7% dietary fiber. Fifty‐six male weanling Sprague‐Dawley rats were randomly assigned to four diets containing 5% cellulose (C5); 10.5% cellulose (C10); 21.5% coarse (2 mm) wheat bran (CB); or 22.2% fine (0.5 mm) wheat bran (FB) in a sixweek study. Dietary fiber digestibilities were significantly different (P < 0.05) among treatment diets (CB > FB > C5 > C10) but there was no effect in fat digestibility among treatments. High‐fiber diets fed to rats resulted in significantly greater wet and dry fecal weights than low‐fiber diets. Bran diets resulted in significantly higher fecal moisture than cellulose diets. Cecum lengths increased significantly with bran diets compared with cellulose diets. The CB diet resulted in significantly higher stomach weights than with cellulose diets. Stomachs were heavier and cecal lengths were greater with bran diets than with cellulose diets; however, a high‐cellulose diet resulted in increased colon weight. Except for higher fiber digestibility of coarse bran, bran particle size had no significant effects. Healthful effects of wheat bran may be associated with gastrointestinal morphology and function. Fecal bulking and decreased intestinal transit time can prevent constipation and may dilute or reduce absorption of toxic or carcinogenic metabolites, thus improving gastrointestinal health and lowering the risk of tumor development and cancer.