Functions and Characteristics of Whey Protein in Sports Nutrition

乳清蛋白是牛乳中一类营养价值较高的优质蛋白,必需氨基酸种类齐全,组成模式与人体相似,并含有丰富的支链氨基酸和多种生物活性物质,能够提高机体的抗氧化能力,增强机体免疫力,促进骨骼肌蛋白质的合成,抑制肌肉蛋白分解,加速训练后体能的恢复,对于运动人群而言,是补充优质蛋白的良好来源.本文就合理的补充乳清蛋白对缓解运动性疲劳、提高运动能力的研究进展进行了综述.     

乳清蛋白提高运动能力的研究进展

从乳清蛋白不同补充形式的角度综述了乳清蛋白对改善运动人群生理指标和提升运动能力等方面的研究进展。     

大豆与乳清蛋白协同释放必需氨基酸的动态模式研究

目的：探讨运动后摄入大豆与乳清混合蛋白,血液中必需氨基酸的动态变化模式。方法：健康洁净级Wistar系雄性大鼠18只随机分为3组：大豆蛋白组、乳清蛋白组和双蛋白组。运动模型采用大鼠静水游泳,建立一次性力竭运动模型。蛋白干预后每隔30min采集尾静脉血,检测9种必需氨基酸浓度的动态变化。结果：与单独补充大豆及乳清蛋白相比,运动后摄入双蛋白能够维持高浓度的色氨酸及支链必需氨基酸持续性释放,2种蛋白的单独摄入或混合摄入不影响除色氨酸外的其他非支链必需氨基酸的释放。结论：运动后及时补充“大豆+乳清”双蛋白能够发挥2种动植物蛋白的协同作用,维持血液中支链必需氨基酸的持续性供给。     

蛋白和抗氧化剂对离心运动后肌肉功能和疼痛的影响

大量研究证实补充蛋白质或抗氧化剂均可有效提高机体的运动能力,然而,蛋白质和抗氧化剂联用的效果尚不清楚。本研究将60只SD大鼠随机分为4组,安静组(CG)、运动组(EG)、蛋白组(PG)和蛋白+抗氧化剂组(PAG),每组15只。PG组大鼠按照0.5 g/kg的剂量灌胃乳清蛋白溶液,PAG组大鼠按照0.5 g/kg的剂量灌胃乳清蛋白和抗氧化剂(富含花青素的浆果提取物)溶液。CG和EG组大鼠灌胃等体积的蒸馏水,共灌胃1周。然后,EG、PG和PAG组大鼠进行90 min的离心运动。采用机械缩足阈值来反映各组大鼠离心运动后的肌肉酸痛程度,研究显示,离心运动48 h后,PG组和PAG组大鼠的机械缩足阈值明显高于EG组,并且PG组和PAG组高于PG组。多项研究均显示,IL-6、IL-1β、MG53和MyoD参与肌肉的损伤及修复过程。本研究检测了上述因子的变化情况,发现大鼠在离心运动48 h后,后胫骨前肌组织中IL-6、IL-1β、MG53和MyoD的蛋白表达水平均显著升高,而蛋白+抗氧化剂可显著抑制上述指标的升高。苏木精伊红(HE)染色显示,离心运动48 h后,运动组大鼠的肌纤维受损程度达39.43%,显著高于蛋白组(23.54%)和蛋白+抗氧化剂组(8.42%)。此外,蛋白和抗氧化剂可显著抑制离心运动诱导的血清肌酸激酶的升高,并提高超氧化物歧化酶的活性。本研究证实蛋白联合抗氧化剂可有效减少离心运动引起的肌肉损伤、抑制机体的炎症反应并降低肌肉酸痛程度。     

慢病人群增加优质蛋白质摄入的思考与建议

优质蛋白质摄入缺乏是我国居民普遍存在的营养问题,是慢病的主要诱因之一。优质蛋白质的足量摄入能够提高机体免疫力,改善营养健康。双蛋白是优质植物蛋白和优质动物蛋白的融合,在增强免疫力、抗疲劳、抗氧化等方面显著优于单一蛋白。因此,在当前防疫的特殊时期,建议科学补充优质蛋白食物,加强对慢病人群的营养健康干预。     

乳清蛋白在临床营养中的应用

乳清蛋白被认为是"蛋白之王",是人乳蛋白的主要成分。乳清蛋白的临床功用包括维持和提高机体免疫力、抗自由基延缓衰老、维持肾功能和促进创伤愈合。疾病防治作用包括防治"四高症"、心脑血管疾病和消化系统疾病,以及有助于癌症康复和AIDS患者的治疗。     

维生素D与乳清蛋白联合干预社区绝经期女性肌肉衰减综合症的研究

目的：探讨单独口服乳清蛋白、维生素D或两者联合补充促进绝经期女性骨骼、骨外健康效应及改善肌肉衰减综合征影响。方法：2015—2016年在北京市王佐镇50岁及以上绝经期女性中,筛选出肌肉衰减综合征的患者80名,并随机分4组,即对照组（普通膳食组）、维生素D组、乳清蛋白组和乳清蛋白联合维生素D干预组。随访半年,重点监测受试者口服维生素D以及乳清蛋白前后血清1,25-（OH）2D3、血生化指标以及上下肢肌力测定,握力、步速等变化的同时,应用ISCCWG诊断标准进行肌量测定,观察ASM指标的变化规律,对比分析4组间患者前述指标在基线以及给予乳清蛋白和维生素D后变化的差异。结果：通过连续6个月每日单独补充800 IU维生素D,可以使受试人群的体内血清1,25-（OH）2D3水平达到30 ng/mL,且恢复到了正常水平（P<0.05）。当同时联合每日30 g乳清蛋白进行干预,6个月以后其受试者体内的血清1,25-（OH）2D3水平也可达到30 ng/mL。通过干预实验的结果表明,受试人群体内的白蛋白水平、体内血清肌酐、四肢骨骼肌量、步速、握力都有了较为明显的提高,尤其在联合补充维生素D和乳清蛋白后,变化更为显著。结论：维生素D、乳清蛋白的干预对受试人群的四肢骨骼肌量、步速、握力都得到了较为明显的改善趋势,尤其在联合补充维生素D和乳清蛋白后,变化更为显著。.     

肌酸提高运动能力的作用

介绍了肌酸在机体的分布与合成及其在肌肉能量代谢中的作用。综述了补充肌酸对提高体内肌酸含量和运动能力的作用 ,并介绍了肌酸提高运动能力作用的机制研究情况     

乳清蛋白及其生物活性肽血压调节功能研究进展

乳清蛋白既是优质蛋白来源，也是抗高血压生物活性肽的理想来源，开发具有调节血压功效的蛋白多肽类产品对未来临床高血压防治将发挥重要作用。文章综述了乳清蛋白生物活性肽血压调节功能的基本机制和研究现状，并对其未来发展趋势和应用前景进行了讨论。     

乳清蛋白肽对衰老模型小鼠的抗氧化和学习记忆改善作用

目的：探讨乳清蛋白肽对衰老模型C57BL/6N小鼠的抗氧化和学习记忆改善作用。方法：采用SPF级雄性C57BL/6N小鼠72只,随机选取12只作为空白对照组,其余小鼠采用D-半乳糖100 mg/kg BW腹腔注射造模,连续造模6 w,期间空白对照组小鼠腹腔注射等量生理盐水。6 w后内眦取血,测定血清MDA水平,并按MDA水平随机分为模型对照组、乳清蛋白组1.5 g/kg BW和3个乳清蛋白肽干预组（0.3、1.5、3.0 g/kg BW）。每日经口灌胃给予受试样品水溶液,干预周期为30 d,期间继续维持模型对照组、乳清蛋白组及乳清蛋白肽组D-半乳糖及空白对照组生理盐水腹腔注射造模。干预结束后,按开阔场实验、水迷宫实验、新物体识别实验顺序进行行为学实验。行为学实验结束后,对小鼠血清、肝脏及脑组织氧化应激相关指标进行检测。结果：与空白对照组相比,D-半乳糖衰老模型小鼠显示出了运动、探索及学习记忆能力障碍,模型组小鼠抗氧化酶水平低于空白组、脂质过氧化和羰基化蛋白水平高于空白组。与模型对照组相比,乳清蛋白肽可显著改善衰老小鼠空间探索、空间及非空间学习记忆能力,并提高血清及肝脏SOD、GSH-Px活力,改善血清及脑组织脂质过氧化物与羰基化蛋白累积水平。结论：乳清蛋白肽对衰老模型小鼠具有抗氧化和改善学习记忆作用。     

Production of High-Viscosity Whey Broths by a Lactose-Utilizing Xanthomonas campestris Strain

Xanthomonas campestris BB-1L was isolated by enrichment and selection by serial passage in a lactose-minimal medium. When BB-1L was subsequently grown in medium containing only 4% whey and 0.05% yeast extract, the lactose was consumed and broth viscosities greater than 500 cps at a 12 s⁻¹ shear rate were produced. Prolonged maintenance in whey resulted in the loss of the ability of BB-1L to produce viscous broths in whey, indicating a reversion to preferential growth on whey protein, like the parent strain.     

Sterol Composition of the Strobilus of Equisetum arvense L.

“Process whey protein” was prepared by heating bovine milk whey protein isolate solution at neutral pH under salt-free conditions. The process whey protein solution, being clear, was heated at various pHs (2.0 to 11.0) and NaCl concentrations (0 to 200 mM), and the turbidity and gel properties of the products were then examined. For comparison, the properties of the whey protein isolate treated under the same conditions were measured. The whey protein isolate formed a transparent gel or sol below pH 3 and above pH 7 at low NaCl concentration after heating, but the process whey protein formed transparent gels and sols over a wider range of pH and NaCl concentrations than those of the whey protein isolate. More elastic, firmer, and denser gels were obtained from the process whey protein than from the whey protein isolate. The process whey protein provides a novel food material with useful properties.     

Functional properties of whey,whey components,and essential amino acids: mechanisms underlying health benefits for active people (review)

Whey proteins and amino acid supplements have a strong position in the sports nutrition market based on the purported quality of proteins and amino acids they provide. Recent studies employing stable isotope methodology demonstrate the ability of whey proteins or amino acid mixtures of similar composition to promote whole body and muscle protein synthesis. Other developing avenues of research explore health benefits of whey that extend beyond protein and basic nutrition. Many bioactive components derived from whey are under study for their ability to offer specific health benefits. These functions are being investigated predominantly in tissue culture systems and animal models. The capacity of these compounds to modulate adiposity, and to enhance immune function and anti-oxidant activity presents new applications potentially suited to the needs of those individuals with active lifestyles. This paper will review the recent literature that describes functional properties of essential amino acids, whey proteins, whey-derived minerals and other compounds and the mechanisms by which they may confer benefits to active people in the context that exercise is a form of metabolic stress. The response to this stress can be positive, as with the accretion of more muscle and improved functionality or greater strength. However, overall benefits may be compromised if immune function or general health is challenged in response to the stress. From a mechanistic standpoint, whey proteins, their composite amino acids, and/or associated compounds may be able to provide substrate and bioactive components to extend the overall benefits of physical activity.     

Biodegradable biocomposite films based on whey protein and zein: barrier, mechanical properties and AFM analysis

Whey and zein protein are byproducts of the food industries and have good film making properties. Single and laminated films were produced from zein protein and whey protein and their film properties were studied. Glycerol and olive oil were used as plasticizer for the single and laminated films. The laminated films exhibited higher ultimate tensile strength (UTS) than the single whey protein films (260% and 200% in the whey-zein-glycerol and whey-zein-olive oil films, respectively). The UTS of the whey protein films increased 2-3-fold after lamination. The laminated films showed higher barrier properties than the single whey protein films (180% in the whey protein-zein-glycerol films and 200% in the whey protein-zein-olive oil films in comparison to single whey protein films) and lower than the single zein films.     

Enzyme-induced aggregation and gelation of proteins

This paper provides a brief overview of the effects of protein hydrolysis on aggregation and gel forming properties of protein systems. Among the food globular proteins, whey proteins and soy proteins are the most extensively studied for their ability to form different textures upon proteolysis. Recent studies were focused on identifying aggregating peptides and on mechanisms of aggregation and gelation.     

Studies on whey fermentation using lactic acid bacteria L. acidophilus and L. bulgaricus

The fermentation process of acid curd whey using pure cultures of L. bulgaricus and L. acidophilus was investigated. The influence of the starter culture amount on the acidification rate in the fermentation was specified, the biological value of fermented and fermented-ammoniated curd whey was determined, and the ability of fermented whey to prevent the injurious effect of Bac. mesenthericus on the wheat bread quality was examined. Acid curd whey was fermented up to a titratable acidity of 19.8–21.6 g lactic acid/kg whey using L. acidophylus and L. bulgaricus. Mathematical equations were developed on the basis of experimental data to calculate the titratable acidity (A) as a functionof fermentation time (τ) and temperature (t). Fermentation and fermentation-ammoniation processes increase the biological value of whey (the content of the vitamins B₁, B₂, B₆, PP and the free amino acids increase). A new dry fodder BIOLAKTS was developed from fermented curd whey and was recommended for use in veterinary medicine. The fermentation-ammoniation process of curd whey was carried out by adding calculated amounts of non-protein nitrogen NH₄OH to increase the total protein equivalent and to achieve mutual proportions of protein and lactose 1:1.4, as in skimmed milk. Fermented-ammoniated curd whey was used to obtain a skimmed milk substitute. A dry flour lactic acid concentrate (FLC) was created as a mixture of high quality wheat flour and evaporated fermented whey in established ratios. As our experiments prove, it can be used as an additive in bread-making to prevent the spoiling of wheat bread by Bac. mesenthericus.     

Dietary whey protein modulates liver glycogen level and glycoregulatory enzyme activities in exercise-trained rats

This study compared the effects of dietary whey protein with dietary casein or soy protein on glycogen storage and glycoregulatory enzyme activities in the liver of sedentary and exercise-trained rats. Male Sprague-Dawley rats (ca. 130 g) were divided into one sedentary and three exercise-trained groups, with eight animals in each group. Casein was provided as the source of dietary protein in the sedentary group while the exercise-trained groups were fed casein, whey, or soy protein. Rats in the exercise-trained groups ran for 30 mins/day, 4 days/week on a motor-driven treadmill. In the exercise-trained rats, animals fed whey protein had higher liver glycogen content than animals in the other two diet groups. Glucokinase activity was significantly higher in rats fed whey protein compared to that in rats fed soy protein, while glucose 6-phosphatase activity was significantly decreased in animals on the whey protein diet compared with those the other two diets. Although 6-phospho-fructokinase activity was significantly lower in the whey protein group than in the soy protein group, we found that fructose 1,6-bisphosphatase activity was significantly higher in the whey group compared with either the casein or soy groups. Pyruvate kinase activity in rats fed the casein diet was significantly higher than in rats fed either the whey or soy protein diets. In addition, hepatic alanine aminotransferase activity and serum alanine level were also increased in the whey protein group compared with the casein or soy protein groups. Taken together, these results demonstrate that the whey protein diet in exercise-trained rats results in significantly higher levels of liver glycogen, because of the combined effects of regulation of rate limiting glycolytic and gluconeogenic enzyme activities and activation of glycogenesis from alanine via alanine amino-transferase.     

Caseinate-Induced Competitive Displacement of Whey Protein from Interfaces

The caseinate-induced competitive displacement of whey protein from planar air-water interfaces was investigated based on atomic force microscopy (AFM) imaging and that from the surfaces of oil droplets immersed in aqueous solution based on AFM force spectroscopy. After the addition of sodium caseinate to the sub-phase, the surface pressure of planar interfacial films of pre-adsorbed whey protein increased from 8 mN/m to up to 21 mN/m. The thicknesses of interfacial films were uniform and remained to be approximately 2 nm at relatively low surface pressures up to 18 mN/m, while they became uneven at higher surface pressures and increased to up to 7.1 nm, presumably due to the compression of interfacial whey protein networks by adsorbed caseinate. The rigidity of oil droplets coated with protein adsorbed to their surfaces was then evaluated based on the slope of approximately linear force-distance curves obtained by pressing an oil droplet against another. The adsorption of whey protein to oil droplet surfaces increased droplets’ rigidity. The subsequent addition of caseinate to the bulk solution surrounding oil droplets coated with pre-adsorbed whey protein further increased droplets’ rigidity. The present results suggest that caseinate adsorbed to an interface to which whey protein had adsorbed in advance did not completely expel pre-adsorbed whey protein molecules into the aqueous phase but caused a compaction of interfacial whey protein networks and thereby strengthened the interfacial film.     

HPLC法分析乳清蛋白对糖尿病模型小鼠血浆氨基酸组分的影响

为寻求有效的氨基酸分离方法并探讨乳清蛋白对2型糖尿病防治的作用机制,采用HPLC法分析乳清蛋白中氨基酸组分及含量;分别以0％、10％、20％和40％的乳清蛋白(WP)灌胃1型、2型糖尿病模型组、正常组小鼠,4周后观察各组血浆氨基酸的变化.乳清蛋白中亮氨酸、异亮氨酸、缬氨酸分别占氨基酸总量的14.40％、5.93％和5....     

Simple purification of immunoglobulins from whey proteins concentrate

We have developed a new protocol with only two steps for purification of immunoglobulins (Ig) from a protein concentrate of whey. Following this protocol, we have an 80% recovery of immunoglobulins, fairly pure. The purification was achieved by eliminating the BSA, via a strong adsorption on DEAE-agarose. Full desoprtion of the other serum proteins could be achieved without contamination with BSA. Thus, a protein solution containing only Ig and very small proteins (e.g., beta-lactoglobulins and alpha-lactalbumin) was obtained. Offering this protein mixture to a lowly activated aminated support, only Ig adsorbed on the support. It has been shown that BSA is able to interact with other proteins (including Ig and lactalbumins). This ability to form complexes with other proteins prevented the success of the direct adsorption of Ig on this mildly activated support, even although Ig should be the largest protein presented in dairy whey.