Effects of dietary fibers on lipid metabolism in liver and adipose tissue in chicks

Two experiments were conducted to investigate the effect of dietary fibers on lipid metabolism with 14-day-old male chicks fed isonitrogenous and isocaloric diets with or without 4% cellulose or 8% alfalfa meal for 3 and 6 weeks. Feeding the cellulose or alfalfa meal resulted in significant reductions in hepatic lipid deposition and plasma lipid content. Hepatic de novo fatty acid synthesis from acetate, glucose and leucine was significantly reduced by feeding the cellulose or alfalfa meal. Triglyceride synthesis from palmitate in the hepatic tissue was significantly reduced by dietary alfalfa meal. Malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+) activity in the hepatic tissue was not affected by feeding the cellulose or alfalfa meal for 3 and 6 weeks. Secretion of lipoprotein from the liver appears to be accelerated by the dietary fibers. Lipoprotein lipase activity in the adipose tissue and clearance rate of intravenously injected lipid were enhanced by feeding the alfalfa meal. Feeding the cellulose for 3 weeks reduced hormone-sensitive lipase activity in the adipose tissue.     

The effect of dietary protein levels on mineral toxicity in chicks.

Studies have been conducted to determine the influence of dietary protein levels of 10, 20, and 30% fed as soybean meal on the toxicity of selenium, cadmium, vanadium, cobalt, and nickel to chicks. The toxicity was evaluated in terms of growth retardation and a decrease in resistance to S. gallinarum infection as measured by mortality. The toxicity of selenium or cadmium was unaffected by the protein level of the diet while the toxicity of vanadium, cobalt and nickel was decreased by increased dietary protein as measured by the interactions on growth. The interactions apparent on growth were not as apparent on resistance to infection indicating that the latter parameter is much less sensitive to these dietary manipulations than is growth.     

Effects of dietary protein deficiency on mineral metabolism and bone mineral density.

The effects of dietary protein restriction on mineral and bone metabolism are uncharacterized. We studied growing rats fed a diet low in protein (5%) for 4, 6, and 8 wks (n = 10 animals/group) and compared them with animals pair-fed with a protein-replete (18%) diet. The low-protein diet rapidly induced a profound hypocalciuria that persisted for greater than or equal to 8 wk. Serum calcium and phosphorus concentrations were not affected but serum total and free 25-dihydroxyvitamin D concentrations as well as gastrointestinal calcium absorption were lower in the low-protein animals. Skeletal dimensions were reduced in the protein-deprived rats but there were no significant differences in bone mineral content between control and low-protein animals at 4, 6, and 8 wks. Hence, dietary protein deprivation resulted in slower growth but bone mineral density was maintained when there was a marked reduction in urinary calcium excretion.     

Effects of dietary aluminum on chicks Gallus gallus domesticus with different dietary intake of calcium and phosphorus

Birds that feed in acidified areas may be exposed to an increased intake of aluminum, while their intake of calcium and phosphorus may simultaneously be low. In particular, juvenile birds foraging in acidified areas may suffer from increased effects of aluminum due to high demands of calcium. Day old chicks were fed six different diets where aluminum was combined with normal and low concentrations of dietary calcium and phosphorus for 14 days. The normal calcium-available phosphorus (Ca-P) level was 1.05%–0.45%, and the low dietary Ca-P level was 0.49%–0.21%. Aluminum was given in dietary levels of 0%, 0.13%, and 0.31%. Aluminum had no effects on growth, mortality, or hematocrit, but induced hypocalcemia.Bones accumulated more aluminum than kidneys. A high dietary concentration of aluminum (0.31%) increased the accumulation of aluminum twofold in bones and threefold in kidneys when the dietary concentration of calcium and phosphorus was halved. Opposed to the predictions, bone mineralisation was stimulated by an intermediate increase in dietary aluminum (0.13%) at both levels of dietary calcium and phosphorus. Bone stiffness was also stimulated at this dietary aluminum concentration, but only at the diet low in calcium and phosphorus. A high dietary aluminum concentration did not have any effect on bone stiffness or calcium concentration. Bone stiffness correlated positively with the calcium concentration in bone, and negatively with the aluminum concentration in bone. The effect of dietary aluminum on bone stiffness is probably caused by an alteration in bone mineralization, rather than by the presence of aluminum in bones.     

Effects of dietary fibers on magnesium absorption in animals and humans

There is overwhelming evidence that dietary fibers are an important component of human and animal diets and play an important role in human health. Because dietary fibers and some associated substances, such as phytate, have in vitro mineral-binding capacities, they have been thought to impair absorption of minerals such as calcium, iron and zinc, although magnesium absorption seems to be less affected. Indeed, the effect of dietary fibers depends largely on their own nature and characteristics, and also on mineral homeostasis. In 1977 it was observed that resistant starch, a fermentable dietary fiber, could improve Mg absorption in rats. More recently, attention has been focused on other fermentable substrates such as inulin and oligo- or polysaccharides, for their potential prebiotic and health effects. Studies conducted on different types of fermentable carbohydrates have confirmed their beneficial effect on Mg absorption in different animal species. The majority of these studies have also sought to determine the effects of fibers on other minerals such as calcium, iron and zinc. In contrast to the studies with Mg, these studies did not show a consistent effect on the absorption of these minerals. This is due to the particularities of sites and mechanism of Mg absorption. To date, four human studies have been carried out that generally confirmed the enhancing effect of fermentable oligo- or polysaccharides on Mg absorption.     

Effects of certain dietary fibers on apparent permeability of the rat intestine

Apparent intestinal permeability was determined indirectly by orally administering a poorly absorbed dye, phenol red, to rats and measuring its recovery in feces and in urine. Increased apparent permeability was recognized by increased dye recovery in urine and by an increased ratio of urinary to fecal dye recovery. Guar gum, pectin, carrageenan type I (80% kappa, 20% lambda), carrageenan type II (iota) and cellulose were each fed at levels of 5 and 15% (wt/wt) of the diet for 31 d to male Fischer 344 rats. The average initial weight of rats was 230 g. Rats fed 15% guar gum gained significantly less weight than most of the other rats (P less than 0.05). Phenol red recovery was measured at 2 and 4 wk after the beginning of the experiment. At 2 wk urinary recoveries of phenol red were high in rats fed fiber-free and carrageenan type II diets, indicating increased apparent permeability. By 4 wk, adaptation had apparently taken place. Urinary dye recoveries were lower in every diet group, and most fiber-containing diet groups gave significantly lower recoveries than did the fiber-free group. Fecal recovery of phenol red was high in the cellulose, carrageenan I, and 5% carrageenan II groups, intermediate in the 5% pectin and 15% carrageenan II groups, and low in the fiber-free, guar gum and 15% pectin groups at both 2 and 4 wk. The ratio of phenol red recovery from urine to that from feces, another index of apparent intestinal permeability, was higher in the fiber-free diet group than in all the other groups. Rats fed 15% dietary fiber had higher average ratios than those fed the same fiber at 5%. These data are consistent with the hypothesis that intestinal permeability to foreign substances may be altered considerably by diet.     

饮食及生活习惯对中老年男性骨密度影响

目的 确定几种常见生活因子对中老年男性骨密度(BMD)的影响,以便指导骨质疏松症的防治工作。方法 对在武汉同济医院高干病房进行体检的286例50～79岁的汉族中老年男性采用问卷方法进行生活饮食习惯等情况调查;用双能量X线骨密度测量仪(DEXA)测定腰椎及股骨颈BMD值,并进行统计分析。结果 (1)将平均每天摄钙量按从低至高分A、B、C₃组,其中年龄在60～69岁的C组腰椎及股骨颈BMD明显高于A组(P<0.01),与B组比较其股骨颈BMD差异也有统计学意义(P<0.05);70～79岁年龄的C组腰椎及股骨颈BMD与A、B组比较均有很大差距,差异有统计学意义(P<0.05)。(2)不同的蛋白质摄入量及饮酒对骨密度的影响不明显。(3)吸烟对骨密度有较大影响,吸烟组股骨颈BMD低于非吸烟组(P<0.05)。(4)运动对骨密度有较大影响,运动组股骨颈BMD高于非运动组(P<0.05)。结论 增加钙的摄入有助骨密度的提高;蛋白质的摄入情况以及饮酒对骨密度影响不大;吸烟促进骨密度的降低;运动有助于骨密度的提高。     

Effects of increased dietary calcium intake upon the calcium and bone mineral status of lactating adolescent and adult women

We studied the effectiveness of an increased calcium (Ca) diet in preventing bone mineral loss in lactating adolescent mothers. Three groups of lactating women were studied: 15 control adolescents consuming their usual Ca diet (900 mg/d), 21 experimental adolescents consuming a high-Ca diet (greater than 1600 mg/d), and 12 adults. At 2 and 16 wk postpartum, serum calcium, phosphate, magnesium, albumin, alkaline phosphatase, vitamin D, parathyroid hormone (PTH), and calcitonin (CT) were determined. Bone mineral analyses were performed by photon absorptiometry. By 16 wk the control adolescent group had a 10% decrease in bone mineral content (BMC) and increased PTH and CT. The experimental adolescent and adult groups had no significant change in BMC during the study. There was a positive correlation (r = 0.45, p less than 0.01) between dietary Ca intake and BMC in all adolescents. Data suggest that bone loss during lactation in adolescents may be prevented with adequate dietary Ca intakes.     

营养教育与膳食干预对中老年骨质疏松患者营养状况和骨密度的影响

目的探讨营养教育与膳食干预对中老年骨质疏松患者营养状况和骨密度的影响。方法将2013年5月至2014年5月在唐山市某三甲医院诊断为骨质疏松并自愿参与调查的90例中老年患者随机分为干预组(45例)和对照组(45例),对两组患者进行常规的骨质疏松治疗,对干预组患者在常规治疗基础上加强营养教育与膳食干预,包括集体授课、面对面营养健康咨询及指导、发放宣传手册、膳食调查及指导等内容,干预期6个月,分析干预前后两组患者膳食结构、粗粮、奶类、豆类及海产品的食用频率、各营养素摄入量等营养状况及骨密度的改变。结果 (1)干预后,谷类、蔬菜、水果、蛋类、奶类、豆类的摄入量符合推荐摄入量的患者比例,干预组高于对照组,差异有统计学意义(P0.05);两组患者肉类和油脂类的摄入差异无统计学意义。(2)干预后两组患者食用粗粮、奶类、豆类及海产品的频率比较,差异有统计学意义(P0.05)。(3)干预后,干预组患者蛋白质、维生素A、维生素C、钙、锌、镁、膳食纤维的摄入量均优于对照组患者,差异有统计学意义(P0.05)。(4)干预后,干预组患者的腰椎及股骨颈的骨密度均高于对照组,差异均有统计学意义(P0.05);干预前后两组患者的腰椎及股骨颈骨密度组内比较的差异均有统计学意义(P0.05)。结论营养教育与膳食干预能够促进中老年骨质疏松患者膳食的合理摄入,改善患者自身的健康状况,增加骨密度,从而提高常规治疗效果。     

Effects of dietary protein intake on carnitine status in Thai men

Healthy men receiving adequate intakes of energy and fat without protein and carnitine for 14 days had significantly higher mean 24-h urinary free, acyl, and total carnitine excretions than the control subjects. Hen egg was the sole source of protein in this study and constained 7.77 μmol of carnitine/100 g. The stress stimuli due to the lack of protein and carnitine intakes were alleviated with the protein intakes of 0.35, 0.50, 0.55, 0.65, 0.70, and 0.85 g/kg/d, evidenced by the significant decreases in the 3 forms of 24-h urinary carnitine excretions. Their significantly lower in the 3 forms of 24-h urinary carnitine excretions than the control subjects with carnitine intake of 176 μmol/d were due to their limited intakes of carnitine: 12–30 μmol/d. Their significant increases in urinary acylcarnitine/total carnitine ratios indicated the utilization of carnitine in fatty acid oxidation.     

Effect of dietary vitamin C on ascites in broiler chicks

A total of 480 day-old broiler chicks were divided randomly into 4 equal groups, each of 4 replicates, and reared for two weeks. To their rations, which contained sodium chloride at 2.5% ascorbic acid was added at the rate of 0, 150, 300 and 450 mg/kg for groups 1, 2, 3 and 4 respectively. Incidences of ascites cases were 20.8, 10.8, 7.5 and 7.5% for the groups 1, 2, 3 and 4 respectively. When vitamin C was added to their rations body weights were increased significantly, but feed consumption remained unchanged. There were no significant differences in water consumption or body moisture. The total serum protein was significantly increased. The packed cell volume was only increased in the chicks that had received 450 mg vitamin C/kg of feed and there were no significant differences in the ascorbic acid content of the plasma. It was concluded that the addition of vitamin C to the chicks' rations reduces the incidence of ascites caused by toxic dietary levels of sodium chloride.     

Effects of dietary fibers and cholestyramine on the activity of pancreatic lipase in vitro

Most experiments were conducted in the presence of human gallbladder bile; colipase and pancreatic lipase were purified using porcine pancreas. The adsorption of bile salts, phospholipids and cholesterol from the bile, together with that of pancreatic lipase was measured on wheat bran, cellulose, hemicellulose (xylan), slightly methylated pectin (42%) and cholestyramine. In contrast to cholestyramine which intensively binds biliary lipids (61.7-81.7%) and pancreatic lipase (47.5%), the fibers studied only had a low adsorbent power. The direct influence of these fibers and of cholestyramine at concentrations ranging from 0-5% on lipase activity was measured at constant pH, using two conventional assay systems, long chain triglycerides and tributyrin. In the presence of human bile and colipase, a drastic reduction in triglyceride hydrolysis by lipase was observed with cholestyramine (loss of 66-82%) and wheat bran (loss of 77-94%) at 1% concentration. The other fibers did not have any marked effects on enzyme activity. The use of a radio labeled lipase made it possible to demonstrate that the inhibitory effect of bran on enzyme activity was independent of adsorption phenomena on bran. The fraction of bran that can be solubilized in the aqueous phase, in fact, induced this reduction in activity. The presence of protein inhibitor in bran may be responsible for the reduction in pancreatic lipase activity.     

Effects of dietary fibers on nonfasting plasma lipoprotein and apolipoprotein levels in rats.

This study was undertaken to determine whether selected dietary fibers had an effect on plasma lipoproteins, apolipoproteins and enzymes involved in cholesterol metabolism in rats. Each experimental diet contained 8% dietary fiber by weight; all animals were killed in a nonfasted state. After 4 wk, final body weight and liver cholesterol were similar in fiber-free controls and in rats fed diets containing cellulose, pectin, oat bran or wheat bran. Pectin-fed animals has significantly lower plasma cholesterol, HDL-cholesterol and apolipoprotein A-I levels, and exhibited significantly higher hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity than did the fiber-free control group. In addition, plasma triglyceride concentrations were lowest in pectin-fed animals. These multiple effects on lipid metabolism were not observed when oat bran, containing one-third soluble fiber, was used. Although total plasma cholesterol levels in wheat bran-fed animals were not different from those in the fiber-free controls or the cellulose-oat bran-fed animals, the LDL cholesterol level was significantly higher than in fiber-free controls or pectin-fed animals. This study demonstrate that dietary fibers included in the diet of rats are able to alter nonfasting lipoprotein cholesterol and apolipoproteins and that pectin, a soluble fiber, was most effective in lowering plasma cholesterol levels.     

Effects of dietary lipid composition and inulin-type fructans on mineral bioavailability in growing rats

ObjectiveThis study reports the effects of feeding with a combination of inulin-type fructans (ITF) and fish oil (FO) on mineral absorption and bioavailability as part of a semipurified diet offered to rats.MethodsMale Wistar rats (n = 24) were fed a 15% lipid diet (soybean oil [SO] or a 1:0.3 fish:soybean oil mixture [FSO]) and diets containing the same sources of lipids supplemented with 10% ITF (Raftilose Synergy 1) ad libitum for 15 d. Feces and urine were collected for mineral analyses during the last 5 d of the test period. Fatty acid composition was determined in liver and cecal mucosa homogenates. Liver and bone mineral analyses were performed by atomic absorption spectrophotometry. Bone biomechanical analyses were evaluated by a 3-point bending test.ResultsCompared with the controls, ITF-fed rats had enlarged ceca and a significant decrease in cecal content pH (P < 0.001). The apparent mineral absorption was improved in these rats, and this effect was enhanced by dietary combination with FO for all minerals except for magnesium. Addition of ITF to the diet resulted in higher bone mineral content (calcium and zinc) and bone strength, but increased bone mineral content was only statistically significant in FO-fed animals. A decrease in liver iron stores (P = 0.015) was observed in rats fed FO, considering that ITF consumption returned to levels comparable to the SO control group.ConclusionThese findings confirm the positive influence of ITF on mineral bioavailability, which was potentiated by addition of FO to the diet.