Bioavailability of iron in ground beef and plant protein concentrates

Weanling male Wistar rats were fed a low iron basal diet for 4 weeks. They were then divided into 16 groups according to a randomized block design based on hemoglobin level. During the repletion period of 2 weeks, one group was fed the basal diet. The other fifteen groups received ferrous sulphate, freeze-dried ground beef, ground granular soy product, a 2:1 mixture of beef and the soy product, or rapeseed protein concentrate as iron sources at three levels. All diets were isocaloric and isonitrogenous. The efficiency of iron utilization was calculated on the basis of iron gained in hemoglobin and iron consumed, applying appropriate correction for iron obtained from the ingredients of the basal diet. The relative biological value (RBV) of iron in the test source was calculated as the ratio between the efficiency for the test and the standard source (ferrous sulphate). The RBVs were: freeze-dried ground beef, 0.53; ground soy product, 0.62; 2:1 mixture of beef and soy product, 0.71; rapeseed protein concentrate, 0.55. The low availability of iron in beef containing 60% heme iron indicated that the anemic rat is not a suitable model for normal man, since the absorption of heme iron by man is much higher than that of inorganic or non-heme iron.     

Effect of cholesterol supplementation on plasma and liver cholesteryl ester fatty acids in rats fed casein or soy protein

The effect of supplementation with cholesterol on plasma and liver cholesteryl ester fatty acids was examined in rats fed diets containing different protein sources. Weanling male rats were fed a semi-purified diet containing 20% casein or 20% soy protein for seven weeks and then 1% (by weight) of cholesterol was added for three more weeks. Rats fed soy protein grew consistently slower than those fed casein. The plasma and liver cholesterol contents were not significantly different between the two protein groups in the unsupplemented rats; however, they were significantly increased in cholesterol-fed animals, particularly in casein-fed rats. Analysis of the cholesteryl ester fatty acid composition in plasma and liver demonstrated that cholesterol-feeding significantly increased the levels of saturated fatty acids, monounsaturated fatty acids and linoleic acid in casein-fed rats as compared to those fed soy protein. The level of cholesteryl arachidonate in liver, which was low initially, increased slightly in the liver of casein-fed rats but did not significantly change in the plasma of either protein group.     

大米蛋白调控生长期幼鼠及成熟期大鼠肝脏脂类水平的研究

目的探讨大米蛋白对生长期幼鼠及成熟期大鼠肝脏脂类水平的调控效果及年龄对调控效果的影响作用。方法分别给雄性Wistar 7周龄幼鼠及20周龄大鼠投喂CP为20%及14%的大米蛋白、大豆蛋白、酪蛋白2 w后,检测各组幼鼠、大鼠肝脏总脂质、肝脏总胆固醇及肝脏甘油三酯含量。结果各实验组间幼鼠及大鼠生长效率差异无统计学意义。与酪蛋白组相比,大米蛋白组、大豆蛋白组幼鼠及大鼠的肝脏总脂质水平、肝脏总胆固醇含量、肝脏甘油三酯含量显著降低（P〈0.05）。相对于酪蛋白组,大米蛋白降低幼鼠及大鼠肝脏总脂质、肝脏总胆固醇、肝脏甘油三酯的程度差异无统计学意义（P〉0.05）。大米蛋白组与大豆蛋白组间各检测指标差异无统计学意义（P〉0.05）。结论在正常的膳食条件下,大米蛋白能够显著降低生长期幼鼠及成熟期大鼠肝脏脂类含量,显示与大豆蛋白一致的降低肝脏脂类水平的作用效果,并不受年龄的影响与制约。     

Growth and composition of brain myelin lipid in rats raised on restricted casein and soy protein diets

Studies were made in weanling and post-weanling rats to compare the effects of restricted dietary levels (8%) of casein (CS) and soy protein (SP) on the lipid composition of brain myelin, isolated by discontinuous sucrose density gradient ultracentrifugation. Diets containing normal levels (25%) of SP and CS (control), were also investigated. With the restricted protein diets, but not the 25% SP diet, there were significant reductions in the quantities of myelin, and of myelin lipid classes, relative to control. These deficits, including those of growth and body weight (but not brain weight), were greater at weaning than at 6 weeks of age. The severity of the deficits at each age, differed very significantly, depending on the type of dietary protein fed. Concerning the individual phospholipids at weaning, the restricted protein diets resulted in significantly lower values relative to control; these values were more depressed with the 8% SP than with 8% CS diet. The results were explained on the basis of a possible greater amino acid imbalance in the low protein SP diet than the corresponding CS diet.     

Effect of soy milk and bifidobacterium-fermented soy milk on plasma and liver lipids in ovariectomized Syrian hamsters

The effects of soy milk and fermented soy milk on lipid metabolism were studied in ovariectomized Syrian hamsters. Five mo-old Syrian hamsters were randomly assigned to four treatment groups: ovariectomized (OVX)+control diet (OVX-C); OVX+soy milk diet (OVX-SM); OVX+fermented soy milk diet (OVX-FSM); and sham-operated+control diet (Sham-C). The hamsters were fed on these diets for 4 wk. The atherogenic index value of the OVX-FSM group was lower than that of the OVX-C group. The plasma triglyceride level of the OVX-FSM group was significantly lower than that of the OVX-C group. The liver total cholesterol contents in the OVX-SM and OVX-FSM groups were significantly lower than that in the OVX-C group. Thus, these results demonstrate that bifidobacterium-fermented soy milk had a hypolipidemic effect in ovariectomized hamsters.     

大豆蛋白和高钙摄入对高血胆固醇模型大鼠血脂水平的影响

目的探讨膳食大豆蛋白和/或高钙摄入对高血胆固醇模型大鼠血浆胆固醇及有关血脂指标的影响.方法用含5%猪油、1%胆固醇和0.25%胆碱的高脂饲料喂饲健康Wistar雌性大鼠,经14d诱发高血胆固醇以后,测血浆总胆固醇(TC),总甘油三酯(TG),高密度脂蛋白胆固醇(HDL-C)和载脂蛋白B(ApoB100)的浓度.然后,按体重和血浆胆固醇浓度将动物均衡分为4组,以2×2析因设计,分别喂饲含有酪蛋白和大豆分离蛋白及正常钙(0.59%)和高钙水平(1.12%)的纯合成高脂饲料.经21d喂养后,采血,测定指标同前.实验结果用SPSS统计软件进行方差分析.结果经14d诱导高血脂后,实验模型大鼠的TC水平为(4.10±1.11)mmol/L(n=24),而喂饲正常饲料的阴性对照鼠仅为(1.92±0.28)mmol/L(n=8),升高了2.14倍.又经21d喂饲含有处理因素的饲料后,酪蛋白组,酪蛋白加钙组,大豆蛋白组和大豆蛋白加钙组大鼠的TC水平分别为(10.56±2.74,7.99±2.19,5.48±0.51和6.81±0.98)mmol/L;ApoB100为(0.46±0.14,0.31±0.12,0.17±0.07和0.21±0.05)g/L.同酪蛋白组相比,其他3组动物的TC和ApoB100浓度显著降低.而各组间TG和HDL-C的变化均无显著性.结论膳食大豆蛋白和/或高钙摄入均可降低高血胆固醇模型大鼠的TC和ApoB100浓度,但对TG和HDL-C的作用不明显.大豆蛋白是这种作用的主要因素,但同时存在大豆蛋白和高钙摄入的相互作用.膳食大豆蛋白和高钙摄入的降血胆固醇机制还需要进一步探讨和研究.     

大豆蛋白对高血胆固醇模型大鼠胆固醇代谢的影响

目的:探讨膳食大豆蛋白对高胆固醇模型大鼠血浆胆固醇及其有关血脂指标的影响,并对其可能的作用机理加以研究。方法: 4周龄断乳雄性Wistar大鼠,经28d诱发高血胆固醇以后,按体重和血浆总胆固醇浓度将动物均衡分为两组,分别喂饲含酪蛋白和大豆蛋白的纯合成高脂饲料56d。结果:经28d诱导高脂模型后,高血胆固醇模型大鼠的TC浓度是阴性对照组的1 51倍。又经56d喂饲含有处理因素的饲料后,同酪蛋白组相比,大豆蛋白组动物TC,TG,apoB含量显著降低,而FT4水平显著高于酪蛋白组(P<0. 05)。膳食大豆蛋白摄入可降低高血胆固醇模型大鼠TC、TG、apoB浓度、使血浆FT4含量增高,但对HDL-C,apoA,FT3,TSH和胰岛素(INS)水平无影响。结论:大豆蛋白可影响血浆胆固醇水平,但其相应的作用机理还需进一步探讨。     

Effect of soy product kinako and fish oil on serum lipids and glucose metabolism in women with metabolic syndrome

ObjectivesAt the doses typically used to treat hypertriacylglycerolemia, fish oil may increase low-density lipoprotein (LDL) cholesterol and blood glucose levels. The aim of the present study was to verify whether soy could attenuate the effects of fish oil on blood lipids and carbohydrate metabolism in patients with metabolic syndrome.MethodsSixty-five women (47.9 ± 9.98 y) were studied with the use of a parallel, randomized design. The control group maintained the usual diet; the second group received 29.14 g/d of soy (kinako); the third group received 3 g/d of fish oil n-3 fatty acids; and the fourth group received fish oil (3 g/d) and kinako (29.14 g/d). Assessments were performed at baseline and after 45 and 90 d.ResultsIn relation to baseline values, fish oil increased (P < 0.05) total and LDL cholesterol, glucose, insulin, and homeostasis model assessment of insulin resistance levels after 90 d. Comparisons among groups demonstrated a decrease (P < 0.05) in total cholesterol in the fish oil and kinako group after 90 d as compared with the fish oil group. LDL cholesterol decreased (P < 0.01) in the kinako group as compared with the fish oil group. Blood glucose and homeostasis model assessment of insulin resistance levels decreased after 90 d (P < 0.01 and P < 0.05, respectively) and insulin levels decreased (P < 0.05) after 45 d when the kinako group was compared with the fish oil group.ConclusionsThe present study showed that kinako moderates the adverse effects of high doses of fish oil on LDL cholesterol, total cholesterol, and glucose metabolism levels.     

Effects of gamma irradiated,cooked soy‐, beef‐, and soy/meat‐based diets in rats

There is increased demand for microbiologically safe foods. Ionizing energy (referred to as radiation pasteurization or irradiation) is effective in reducing the level of pathogenic organisms such as Salmonella, Trichinae, and Campylobacter which affect the health each year of many people. The irradiation of phytate (IP6), known to bind essential minerals in beef, soy, and soy‐extended beef, at an absorbed dosage of less than 4 kilogray (kGy) caused no difference (P > 0.05) in the level of IP3–6 compared with non‐irradiated samples. In a 3‐wk study, 84 weanling rats (12 groups, 7 per group) consumed diets containing irradiated and non‐irradiated soy, beef, and a soy‐beef combination fed at 20% of the diet. There were no differences in liver and tibia mineral concentrations. Moreover, there was no measurable effect on body weight, feed efficiency, survival of experimental animals, nor on any of the 4 blood or 7 biochemical parameters measured. In addition, the phytate:zinc and the [phytate × calcium]:zinc molar ratios of the diets were calculated as an estimation of potential zinc deficiency. Microbiological tests, performed both before and after irradiation, on the soy‐extended meat and meat patties used as dietary ingredients demonstrated a reduction in the bioload as a consequence of irradiation. Thus, irradiation at the dosage described above had no negative nutritional effects, was unable to enhance hydrolysis of phytate yet reduced the number of microorganisms in the animal food.     

大豆蛋白对高脂饲料喂养大鼠固醇调节元件结合蛋白基因表达的影响

目的探讨大豆蛋白在正常饮食和高脂饮食状态下对大鼠脂代谢相关固醇调节元件结合蛋白(SREBP)基因表达水平的影响。方法 48只清洁级SD大鼠,按体重随机分为4组,分别喂饲含酪蛋白和大豆蛋白的正常饲料和高脂饲料28d后,脱颈椎处死动物,检测激素指标及基因表达水平。结果大豆蛋白组大鼠血清胰岛素水平和胰岛素/胰高血糖素比值显著低于酪蛋白组(P<0.05);大豆蛋白高脂组大鼠血清胰岛素水平显著低于酪蛋白高脂组(P<0.05);大豆蛋白组和大豆蛋白高脂组大鼠肝脏SREBP-1,2基因表达均分别显著低于酪蛋白组和酪蛋白高脂组(P<0.05);大豆蛋白组和大豆蛋白高脂组大鼠肝脏SREBP-1蛋白表达明显低于酪蛋白组和酪蛋白高脂组(P<0.05)。结论大豆蛋白可能通过影响胰岛素进而影响SREBP-1基因表达来调节血脂水平。     

Dietary soy,meat, and fish proteins modulate the effects of prebiotic raffinose on composition and fermentation of gut microbiota in rats

Soy, meat (mixture of pork and beef), and fish proteins were fed to rats with and without prebiotic raffinose (RAF), and the composition and fermentation of gut microbiota were examined. Bifidobacterium spp. populations were higher, and propionic acid concentration was lower in soy protein-fed than meat protein-fed rats. Likewise, Enterobacteriaceae populations were higher in fish protein-fed rats than other rats. RAF feeding increased Bifidobacterium spp. and decreased Faecalibacterium prausnitzii populations regardless of the dietary protein source. Interactions between dietary proteins and RAF were shown for Lactobacillus spp. and Clostridium perfringens group; the increase of Lactobacillus spp. populations by RAF was seen only for soy protein-fed rats, whereas the reduction of C. perfringens group by RAF was evident in fish and meat protein-fed rats. It is concluded that dietary proteins may differentially modulate the effects of prebiotic oligosaccharides on gut fermentation and microbiota, with differences observed between plant and animal proteins.     

Comparison of dietary casein or soy protein effects on plasma lipids and hormone concentrations in the gerbil (Meriones unguiculatus)

The effects of dietary animal protein (casein) or soy protein (soy isolate) on plasma lipids and hormones were investigated in the gerbil. Diets, fed to male gerbils (initial weight, 60 g) for 4 wk, contained either 18% casein or soy isolate as the protein source. The dietary fat sources were lard (16%) and safflower oil (1%). The cholesterol content of the diet was 0.1%. Plasma total cholesterol concentrations were lower in gerbils fed the soy protein diet (159 mg/dl) than in the gerbils fed the casein diet (190 mg/dl). Absolute HDL-cholesterol concentrations were unaffected by the protein source, but LDL-cholesterol concentrations were lower in the soy-fed gerbils. Thus, the ratio of LDL to HDL cholesterol was lower in the soy-fed gerbils (0.42) compared with the casein-fed gerbils (0.70). Plasma insulin levels were higher in the soy-fed gerbils as were plasma thyroxine and thyroid-stimulating hormone levels. The results indicate that the gerbils can be used to study dietary effects on cholesterol parameters. These data also suggest that changes in plasma thyroxine levels may in part account for the hypocholesterolemic effect of soy protein.     

Effects of soy protein supplemented with methionine on blood lipids and adiposity of rats

OBJECTIVE: The effects of soy protein isolate (SPI) versus casein on blood lipids and adiposity were investigated in rats fed methionine-equivalent diets. METHODS: Twenty-eight male Sprague-Dawley rats (230 to 250 g) were assigned in equal numbers to groups consuming SPI- or casein-based diets (20%) supplemented with L-methionine. After 28 d, blood was collected for triacylglycerol, total cholesterol, and high-density lipoprotein cholesterol assessment and epididymal fat pads were weighed. RESULTS: Food intake (519 +/- 90 versus 490 +/- 115 g), weight gain (144 +/- 35 versus 133 +/- 28 g), food efficiency ratio (0.29 +/- 0.09 versus 0.28 +/- 0.06), epididymal fat pad weights (5.409 +/- 2.076 versus 4.768 +/- 1.867 g), and serum concentrations of triacylglycerol (96.3 +/- 41.8 versus 93.4 +/- 37.4 mg/dL) and high-density lipoprotein cholesterol (32.6 +/- 7.4 versus 33.8 +/- 4.4 mg/dL) were similar between the casein and SPI groups, respectively. However, total cholesterol (73.8 +/- 17.8 versus 59.3 +/- 11.9 mg/dL) concentration was higher for the casein-fed rats than for the SPI-fed rats, respectively (P < 0.05). CONCLUSIONS: These results suggest that methionine supplementation may eliminate the decreased fat deposition previously ascribed to soy protein; however, methionine did not abolish the commonly observed hypocholesterolemic effects of soy.     

不同来源的蛋白质对大鼠血脂水平的影响

目的研究雄性大鼠在长期摄入不同来源和含量的蛋白质饲料后,其血脂水平及各血脂比值的变化。方法将断乳雄性大鼠按体重随机分为4组(n=15),分别给予牛奶粉(HM组和LM组)或大豆粉/蛋清粉(HS组和LS组)为蛋白质来源的饲料(每种饲料中总蛋白质含量分别为18%和9%),持续喂养20周后,检测各组大鼠血清中血脂水平,并计算各类血脂的比值。结果在各实验组中,HM组大鼠血清总胆固醇(TC)和高密度脂蛋白胆固醇(HDL-C)水平最高(P<0.05),TC/HDL-C比值最低(P<0.05);HS组大鼠甘油三酯(TG)水平最低(P<0.05)。HS与HM组的TG/HDL-C比值低于LS与LM组(P<0.05)。LS与HS组低密度脂蛋白胆固醇(LDL-C)水平和LDL-C/HDL-C比值均低于LM与HM组(P<0.05)。结论给予高剂量大豆粉来源蛋白质,可以显著降低大鼠的TG水平;若长期给予高剂量牛奶粉作为蛋白质来源,可明显升高大鼠血清胆固醇总体水平。     

大豆异黄酮对高胆固醇模型大鼠血清胆固醇浓度和肝脏胆固醇代谢的影响

目的观察大豆异黄酮对高脂模型大鼠血清胆固醇浓度及其肝脏胆固醇代谢关键酶基因表达的影响。方法 9周龄SD雄性大鼠8只喂饲AIN93M饲料（阴性对照组）,18只喂饲高脂饲料建立高胆固醇模型。14 d后将高胆固醇大鼠随机分为异黄酮组（每天灌胃360 mg/kg BW大豆异黄酮）和高脂对照组,喂饲高脂饲料至实验结束。30 d后测血脂,实时定量聚合酶链式反应（polymerase chain reaction,PCR）测定肝脏羟甲戊二酰辅酶A还原酶（3-hydroxy-3-methylglutaryl-Coenzyme A reductase,Hmgcr）、胆固醇7α-羟化酶（cytochrome P450,family 7,subfamily a,polypeptide 1,Cyp7a1）、低密度脂蛋白受体（low density lipoprotein receptor,Ldlr）mRNA表达量。结果异黄酮组大鼠血清总胆固醇（total cholesterol,TC）和低密度脂蛋白胆固醇（low density lipoprotein cholesterol,LDLC）浓度分别比高脂对照组降低了23.7%（q=2.79,P=0.010）和23.2%（q=2.63,P=0.015）;动物肝脏的Hmgcr和Cyp7a1 mRNA表达量均出现下降,但差异无统计学意义（均有P〉0.05）。结论大豆异黄酮可明显降低高胆固醇大鼠血清TC和LDLC浓度,有可能影响肝脏胆固醇代谢。     

不同来源膳食蛋白质对大鼠体重及其血脂的影响

目的探讨不同膳食蛋白质摄入对大鼠体重及其血脂的长期动态影响。方法选用36只雄性成年Wistar大鼠,按体重随机分为酪蛋白组、大豆蛋白组和谷豆蛋白混合组,喂养12周,检测大鼠在体重及其血脂上的变化。结果大豆蛋白组体重、脂肪湿重、脂体比、TG和TC水平均显著低于酪蛋白组相应指标(P<0.05),HDL-C水平与酪蛋白组相比无统计学差异;谷豆蛋白混合组TC和TG水平均显著低于酪蛋白组和大豆蛋白组(P<0.05),HDL-C水平高于酪蛋白组,有统计学差异(P<0.05)。结论大豆蛋白可以降低大鼠TC和TG水平,谷豆蛋白混合后对TC和TG水平降低作用更明显,并有提高HDL-C的作用。