学龄前儿童氮平衡测定及蛋白质适宜摄入量探讨

以发育正常,身体健康,蛋白质营养状况良好的4～7岁幼儿园寄宿儿童105人为对象,观察摄入不同量蛋白质膳食情况下的氮平衡,15批试验结果表明:摄入蛋白质g/MJ(x)与储存氮g/kg(y)之间有显著相关(r=0.6709,n=15,p<0.01),回归方程(?)=0.0198x-0.1042。正常儿童储存氮平均0.06g/kg,代入上式应摄入蛋白质8.29g/MJ,如每日摄入6.3MJ(1500kcal)时,蛋白质适宜摄入量应为52g。     

浙江省城市居民膳食蛋白质摄入状况分析

目的分析浙江省城市居民膳食蛋白质摄入状况。方法于2009-2011年运用3天24小时回顾法和称重法对浙江省城市共3452名2岁及以上居民进行膳食调查,获得居民每日食物、蛋白质和必需氨基酸摄入量,结合人口学信息对蛋白质摄入进行统计分析。结果纳入分析的膳食调查人数为3240人。蛋白质摄入量为每标准人日71.1g,低于蛋白质推荐摄入量(RNI)80%的人群占34.3%,优质蛋白质占蛋白质供给量的51.7%。各种必需氨基酸的氨基酸比值系数接近1,氨基酸比值系数分等于85,随着文化程度的提高蛋白质摄入量大于等于RNI的比例也随着之增加(OR=0.822,P0.001)。结论浙江省城市居民膳食蛋白质摄入量合理,优质蛋白质比例适当,必需氨基酸组成含量比例与WHO/FAO推荐模式相近,膳食蛋白质营养价值高。蛋白质摄入量随着文化程度的增高而增加。浙江省城市居民存在蛋白质摄入不足的风险,以老年男性和育龄女性最为突出。     

三例慢性放射病患者的氮平衡观察

选择三例慢性放射病患者进行了两期氮平衡实验,每期三日。第一期:当膳食中蛋白质摄入量为75.4～77.2g,热量为1586～1669kcal时,氮平衡为-0.01～-0.50g,第二期:当膳食中蛋白质和热量分别增加至97.2g和2467～2483kcal时,氮平衡为+2.37～+2.93g。两期的蛋白质、脂肪、糖的表观消化率基本相似,显然第一期出现的负氮平衡与蛋白质和热量摄取量不足有关。文中指出,在治疗慢性放射病患者时,应注意供给高热量和高蛋白质的膳食。     

大理医学院部分女大学生膳食营养状况分析

目的：了解医学院女大学生膳食素摄入情况。方法：采用24h膳食记录和称重法，连续3d调查医大二、三年级女生膳食，并进行实验室生化检查，结果：护理专业女生能量摄入量只达RDA的45．2％，早餐占全日热量的17．7％，动物性脂肪大于植物性脂肪，蛋白质主要来源于植物性食品，优质蛋白质摄入量适宜；钙、维生素A、维生素B2摄入量不足。结论：该医学院女大学生膳食状况离平衡膳食相差较远，能量摄入严重不足，建议调整膳食结构，提高膳食能量，植物性脂肪、维生素A、维生素B2的摄入量，减少动物性脂肪摄入量。     

维持性血液透析的79例患者膳食结构调查分析

目的了解维持性血液透析患者的膳食结构及饮食习惯,为维持性血液透析患者平衡膳食、合理营养提供科学依据。方法选取2012年10月—2013年2月在无锡市某三甲医院血液透析中心透析的79例患者,进行膳食情况及个人基本情况调查资料;采用24h膳食回顾的调查方法获取膳食信息,依据中国营养学会2000年修订的《中国居民膳食营养素参考摄入量》标准（DRIs）进行评价。结果79例维持性血液透析患者在能量、蛋白质、脂肪、碳水化合物、钙、磷等都存在不同程度的摄人量不足,其中,蛋白质摄入尤其缺乏,25～49岁男性患者蛋白质摄入量占推荐量的68．63％,50～59岁男性患者蛋白质摄人量占推荐量的62．75％,50—59岁女性患者蛋白质摄入量占推荐量的62．35％。患者钙摄人量只占推荐量49．96％;钠摄人量占推荐量的157．89％。结论膳食结构不均衡,能量、蛋白质、钙摄入不足是维持性血液透析患者的主要特点,建议增加谷类、禽肉类、水产类、蔬菜类等营养丰富的食品以提高能量、蛋白质摄入,提高患者的营养状况,延长他们的生存期及提高其生活质量。     

慢性肾功能衰竭的饮食治疗及护理

1 供给优质蛋白质和必需氨基酸应尽量选用含必需氨基酸的优质蛋白食品,如鸡蛋、牛奶、瘦肉等。这些食品蛋白质的生理价值最高。而大豆、大米、面粉所含非必需氨基酸较高,应予限制,否则不利于氮质排出。当然膳食中蛋白质供量多少,主要取决于患者的症状及肾功能损害程度。早期肾衰蛋白质供给量按0.6g/kg/d,限制磷低于75mg/d。晚期肾衰,优质蛋白的供给量0.38g/kg/d,     

学龄儿童脂肪摄入量调查分析

以北京某小学9～11岁学龄儿童202名为研究对象进行3日膳食调查。结果表明．平均每人每日摄入总热量6538．8KJ，占供给量标准的76．23％。热量来源：蛋白质占13．3％，脂肪占39．2％，碳水化合物占47.4％。脂肪摄入量68．2g，其中动物性脂肪35.9g．占脂肪总量的53％，摄入不饱和脂肪酸14．3g，饱和脂肪酸18.5g，P／S比值为0.77，胆固醇摄入量为430.3mg。上述结果表明该人群热能摄入量不足，而脂肪供热比偏高．摄入胆固醇量偏高。文中建议改善学龄儿童的膳食．增加主食量，减少动物性脂肪和含胆固醇多的食物摄入量，以利于学龄儿童身体健康。     

我国成年男子蛋白质需要量的研究

用短期和长期的氮平衡方法测定了我国成年男子吃动植物混合膳食时蛋白质的需要量。受试者均为成年男性职工,短期组10名,长期组6名。短期组平均年龄、体重和身高分别为37.9岁、64.3kg及173cm;长期组分别为30.2岁、67.7kg及171cm。 短期组实验分5期,每期14天,第一天吃低氮膳、第2～11天吃实验膳,最后3天吃一般膳食,不加限制。各期蛋白质水平按实验顺序分别为0.60、0.73、0.42、0.90和1.05g/kg体重/日;长期组实验期为三个月,蛋白质水平为0.93(0.91～0.94)g/kg体重/日。用凯氏定氮法测定了各代谢期中主副食及粪尿中氮的合量。短期组结果表明,在0.42、0.60和0.73g水平时,机体均处于负氮平衡状态,在0.90g时多数达到正氮平衡,而至1.05g时全部达到正氮平衡。通过直线回归方程式计算,y=-47.75±0.32x(n=46,r=0.83、P<0.01),当y=0时,x=129.4～192.5mg氮,平均为147.7±18.6mg氮,相当于每日每公斤体重摄入0.92g蛋白质才能达到氮平衡。长期组的结果表明,当蛋白质水平为0.93g/kg体重/日,在为期三个月的实验中即可维持机体正氮平衡。二组结果相一致。若加上维持氮平衡平均摄入量的二个标准差作为安全系数,则蛋白质的需要量为1.16g/kg体重/日。     

山东省体育运动技术学院部分学员营养现况调查

为了解体育院校学员的营养状况,用称重法对山东省体育运动技术学院的部分学员进行了膳食调查,并进行了体格及生化检查。结果表明:马拉松学员热能摄入量基本能满足机体需要,体操队学员热能摄入量较低。被调查的学员摄入蛋白质占总热能的15％～19％,E／T(必需氨基酸／总氨基酸)为35.4±2.9％.说明蛋白质质量较高,脂肪占总热能的32％～57％,P／S(多不饱和脂肪酸／饱和脂肪酸)为0.53±0.12,说明脂肪摄入过多,且饱和脂肪酸所占比例较高;碳水化合物摄入量较少,仅占总热能的26％～50％。马拉松学员钙的钙摄入量不足,体操队学员钙、铁摄入均不足。大部分学员维生素摄入不足,但由于学员经常服用维生素制剂,故无维生素缺乏症出现。被调查学员氮平衡略呈正值。     

慢性肾功能衰竭的饮食治疗及护理

慢性肾炎最终会导致慢性肾功能衰竭,它严重地威肋着病人的生命。食疗可减轻肾脏负担,有计划的饮食治疗,可延缓和阻断慢性肾衰的进展。为此,我们在护理工作中实施如下。1 供给优质蛋白质和必需氨基酸,尽量选用含必需氨基酸的优质蛋白质食品如鸡蛋、牛奶、瘦肉生理价值最高,含必需氨基酸比例与人体蛋白最相似。豆类蛋白质高达40％,大米、面粉所含非必需氨基酸较高应予限制,否则不利氮质的排出。膳食中蛋白质的供给取决于患者症状及肾功能损害程度,一般按0.5g/kg/日,体重计算,每日供给量不低于 20g,因人     

Low protein diet and ketosteril in predialysis patients with renal failure

After a short review of the contemporary understanding of amino acid supplementation to low protein diets in patients with uremia we present the results of administration of ketosteril in 20 low-protein-diet patients on such a diet. MATERIAL AND METHODS: Twenty patients (10 men and 10 women) with stable II and III stage chronic renal failure were assigned to a low protein diet (protein up to 40 g/day). Ketosteril (6 tablets a day) were added to the diet. Some of the basic markers of protein metabolism and nitrogen balance were followed. RESULTS: No evidence of deteriorated protein synthesis was found in the therapy thus administered. Serum urea and creatinine values did not change and even tended to decrease. Glomerular filtration was found to increase insignificantly more markedly in the patients with renal failure in the early stages. CONCLUSIONS: A low protein diet with increased content of essential amino acids and their keto-analogues does not deteriorate the nitrogen balance of patients with chronic renal failure. By adding essential amino acids and keto-analogues a normal protein metabolism is maintained in spite of the reduce intake of protein substances with the diet. Supplementation of the diet of chronic renal failure patients with essential amino acids and keto-analogues allows a considerable reduction of the protein intake to be achieved which brings about reduction of glomerular hyperfiltration which actually retards the progression of renal failure and improves its short-term prognosis.     

A controlled trial of fixed versus tailored calorie intake in patients receiving intravenous feeding after abdominal surgery

Excessive intravenous calorie intakes have been shown to increase fat deposition and CO2 production with deleterious results. A controlled trial has therefore been performed to determine whether there is clinical benefit from tailoring calorie intake of intravenously fed patients to the patient's metabolic expenditure. Twenty patients requiring intravenous feeding after abdominal surgery were randomly allocated to receive either (i) a constant regimen containing 2 600 calories and 15.55 g nitrogen or (ii) a varied regimen with a fixed calorie: N2 ratio of 167:1 but with the calorie intake adjusted according to the previous day's metabolic expenditure. Only one patient had a requirement of greater than 2 600 calories; there was no difference in mean RQ during intravenous feeding between the constant regimen (0.90 +/- 0.10 s.d.) and the varied regimen (0.90 +/- 0.09 s.d.) and no significant difference in peak CO2 production. Excess calorie intake over expenditure did not correlate with increased positive nitrogen balance but on the varied regimen patients receiving a higher nitrogen intake tended to be in more positive nitrogen balance. This study suggests that a fixed calorie intake of 2 600 calories per day is suitable for adult patients requiring intravenous feeding after abdominal surgery but currently prescribed nitrogen intakes may be suboptimal.     

Minimum protein requirements in liver cirrhosis determined by nitrogen balance measurements at three levels of protein intake

Nitrogen balance at three levels of protein intake was measured in eight patients with cirrhosis of the liver; moreover, at each level of protein intake, the effects on nitrogen balance of branched-chain amino-acid enriched protein and natural protein were compared. From these nitrogen balance data, minimum protein requirements were calculated by linear regression analysis. The patients were in a negative nitrogen balance on a 40 g protein diet (-0.75 +/- 0.15 gN.), and in positive nitrogen balance on 60 g (+1.23 +/- 0.22 gN.) or 80 g of protein per day (+2.77 +/- 0.20 g N.). Their mean minimum protein requirement (48 +/- 5 g of protein/day or 0.75 g/kg/day) is higher than expected in healthy people; the safe level of protein intake (mean + 2 sd) is 58 g per day or 1.2 g/kg/day. Nitrogen balances and protein requirements were not different on branched-chain amino-acid enriched diets. The physical condition of the patients improved when they came into positive nitrogen balance; the higher rates of protein intake were well tolerated without onset of encephalopathy. We conclude that protein requirements are elevated in cirrhosis of the liver; diets supplying less than 60 g of protein per day should not be prescribed in long term treatment of cirrhotic patients.     

Relationship between protein intake and nitrogen balance in obese patients on low energy diet

The effect of nitrogen intake on nitrogen balance was studied in six obese patients receiving low energy diets. They were given a control diet containing 2,000 kcal of energy and 80 g of protein for the first ten days. Then they were given Diet A with 1,100 kcal of energy and 70 g of protein for the next 2 weeks, followed by Diet B with 1,100 kcal of energy and 50 g of protein for 2 weeks. The relationship between nitrogen intake (X, mg/kg) and nitrogen balance (Y, mg/kg) during the low energy diet periods was statistically significant, with Y = 0.388X-60.32 (SD = 17.71, r = +0.67, n = 11, p less than 0.05). The nitrogen and protein requirements were estimated from this equation to be 201.1 mg/kg and 1.26 g/kg, respectively. In our experiment, the nitrogen balance in obese patients was well maintained although total energy was reduced to 1,100 kcal/day in Diet A. It is suggested that protein quantity in the diets should be taken into account when a low energy diet is used for the treatment of obesity.     

Full protein alimentation and nitrogen equilibrium in a renal failure patient treated with continuous hemodiafiltration: a case report of 67 days of continuous hemodiafiltration.

Standard care for patients with renal failure while in an intensive care unit involves traditional hemodialysis or peritoneal dialysis and protein restriction. We present a case of a patient with renal failure supported with continuous arteriovenous hemofiltration with dialysis (CAVH-D) who was given full protein alimentation. Total daily urea clearance was measured from the CAVH-D output. Protein load was 196 +/- 34 g/day while receiving total parenteral nutrition and 164 +/- 30 g/day while receiving enteral alimentation. Serum blood urea nitrogen was controlled between 40 and 75 mg/dL, except during septic episodes. Nitrogen balance was estimated based upon known alimentation protein load and measurable and estimated nitrogenous losses. The patient was potentially in nitrogen equilibrium during most of the dialysis period. The cumulative nitrogen balance was positive by 5.2 g after 67 days of dialysis. Volume of alimentation was 3.49 +/- 0.7 liters/day. With CAVH-D, the renal failure patient can receive full alimentation without volume or protein load limitations. Furthermore, nitrogen balances can be estimated easily while the patient is on CAVH-D.     

外科营养对消化道肿瘤病人术后营养状况的影响

目的比较肠内营养与肠外营养对消化道肿瘤病人术后营养状况的影响。方法将40例消化道肿瘤病人随机分为肠内营养(EN)组和肠外营养(PN)组,每组20例,试验周期为7天。术后第1天开始给予等热量、等氮量的营养支持一周(术后第1天和第2天分别提供热卡19.33～19.97Kcal/kg,氮量0.14～0.15g/kg;术后第3天至第7天每日提供热卡26.9～28.55kcal/kg,氮量0.2～0.21g/kg)。检测术前和术后第8天病人的体重、肱三头肌皮褶厚度、上臂肌围、血浆白蛋白、转铁蛋白、血清氨基酸谱和累计氮平衡等营养指标。结果两组病人均无严重并发症发生。两组病人术后第8天的体重均明显下降(P<0.001),组间无差异。两组病人术后第8天的肱三头肌皮褶厚度和上臂肌围较术前明显减小(P<0.05),而两组间无显著性差异。两组病人血浆白蛋白水平在术后第8天明显下降,而EN组较PN组下降幅度小(P<0.05)。两组病人的血浆转铁蛋白水平在术后与术前相比无明显变化。累计7天氮平衡EN组为(-26.1±15.3)g,而PN组为(-23.4±10.3)g,两组间无明显差异。EN组能明显升高血清天门冬氨酸(ASP)、丝氨酸(SER)、谷氨酸(GLU)、半胱氨酸(CYS)、异亮氨酸(ILE)及苯丙氨酸(PHE)的水平,对于其它氨基酸无明显影响。而PN组经过营养支持后,血清蛋氨酸(MET)浓度升高,组氨酸(HIS)浓度下降,其它氨基酸变化不明显。结论消化道肿瘤病人术后可出现明显的负氮平衡和低蛋白血症。术后早期应激状态下,肠内营养或肠外营养均不能避免机体分解代谢状态。术后早期进行肠内营养是安全、可行、有效的。肠内营养可以达到与肠外营养一样的维持体重和氮平衡的临床疗效。肠内营养较肠外营养能更好地维持血浆白蛋白水平和血清氨基酸水平。     

Influence of increasing dietary intake on whole body protein kinetics in normal man

The whole body protein kinetic response to increasing dietary intake was studied in 20 normal adult male subjects receiving a defined formula diet orally. Each person received the same amount for 5 days at the rate ranging from 150 to 330 mgN/kg. day and 16 to 34 kcal/kg. day, keeping the calorie to nitrogen ratio as constant. Whole body protein flux was measured using a primed constant infusion of 15N glycine and determining isotopic enrichments in the urinary urea and ammonia. Whole body protein synthesis and breakdown rates were calculated from the flux measurement and nitrogen excretion and intake. The mean protein turnover (Q), synthesis (S) and breakdown (C) rates for all subjects were 3.72+/-0.42, 2.47+/-0.47 and 2.12+/-0.39 g protein/kg. day. These values increased with increasing dietary nitrogen intake up to 270+/-4 mgN/kg. day which is twice the daily recommended protein requirement for a normal adult man and then tended to decrease. Nitrogen intake in the range of 150 to 270 mg N/kg. day showed significant positive correlations with nitrogen balance, Q, S and S/C and the protein accretion was due to a relatively large increase in S compared to that in C. When the intake rate exceeded 270 mg N/kg. day, the nitrogen balance was still positive but now due to a larger decrease in C. These results show that the kinetic parameters of whole body protein metabolism in adult man appear to exhibit a maximum at a dietary nitrogen intake twice the daily requirement level. The mechanism of the maintenance of protein balance changes at this threshold.     

Use of urea kinetics in the nutritional care of the acutely ill patient

In acutely ill patients nitrogen balance is often assessed clinically from measurements of protein intake and urinary urea nitrogen. We have utilized urea kinetic modeling to measure urea generation rates, protein catabolic rates and nitrogen balance in 19 acutely ill patients with varying degrees of renal dysfunction and have studied the effect of varying caloric intake on protein balance during a period of fixed protein intake. In patients with measured creatinine clearances equal to or greater than 50 ml/min there was a highly significant correlation between nitrogen balance estimates derived from urea kinetic modeling and those obtained from urinary urea nitrogen (R = 0.939; p less than 0.001). When creatinine clearance measurements were between 20 to 50 ml/min the correlation between the two estimates was poorer (R = 0.337; p less than 0.001). In patients whose creatinine clearance was below 20 ml/min the correlation between measurements was worse still (R = 0.229; p less than 0.002). To determine the effects of increasing caloric intake on protein catabolic rate seven acutely ill patients were studied. When caloric intake was increased from 27.8 to 34.2 kcal/kg/day while on a fixed protein intake of 1.27 g/kg/day there was a significant fall in protein catabolic rate from 1.39 to 0.99 g/kg/day (p less than 0.002). As urea kinetic modeling takes into account changes in blood urea nitrogen, extrarenal losses of urea and the urinary urea pool, it is the preferred method for measuring protein balance in acutely ill patients particularly those with poor renal function. Serial monitoring of protein catabolic rates permits easy continuous assessment of the effect of increasing caloric intake on protein sparing during parenteral hyperalimentation.     

Effect of mild infectious illness on nitrogen metabolism in patients on a modified fast.

To assess the catabolic effects of mild infectious illness on protein metabolism, the metabolic responses to incidental infections were studied in four obese patients undergoing a modified fast consisting of a low calorie diet essentially free of carbohydrate but meeting protein needs. In six infectious episodes investigated, there was no change in urinary nitrogen excretion. Nitrogen balance was positive when protein intake was maintained at 0.8-1 g/kg body weight in four of five episodes, despite intakes of less than 700 kcal. These preliminary data from patients experiencing infections under these conditions suggest possibilities for significant reduction in catabolic losses in other stress situations.     

维持性血液透析患者饮食蛋白摄入和营养状态关系的探讨

目的探讨维持性血液透析患者饮食蛋白摄入和营养状态的关系。方法对北京大学第三医院维持性血液透析患者的饮食蛋白摄入和营养状态进行评估,资料收集包括饮食记录和分析、生化学指标、主观综合营养评估(SGA)及体测量指标四个方面。结果98例临床稳定的血液透析患者,平均标化饮食蛋白质摄入(NDPI)为0.96±0.25g/kg·d,平均标化饮食能量摄入(NDEI)为120.50±31.59kJ/kg·d。营养不良发生率为29%,根据NDPI将病人分为4组。组间各营养参数差异无显著性。结论大部分维持性血液透析病人的实际饮食蛋白摄入低于KDOQI推荐值,而且这种略低的饮食蛋白摄入没有造成病人营养不良发生率的增加。在我国现有的透析条件下需要针对氮平衡的前瞻对照研究确定合理的维持性血液透析病人的饮食蛋白摄入。