肠道梭菌在机体能量过度摄入中的作用

肥胖与肠道菌群对能量的过度摄入有密切的关系。目前发现人体肠道中与肥胖有关的细菌主要有厚壁菌门和拟杆菌门细菌,其中梭菌属是厚壁菌门中非常重要而且数量庞大的一类菌。研究表明肠道梭菌属细菌代谢是导致机体能量摄入过度的主要原因之一。此外,肠道菌的多糖水解酶降解膳食纤维产生短链脂肪酸提供机体额外的能量,细菌脂多糖的吸收增多促进机体能量过度摄入,饥饿诱导脂肪因子的表达受到抑制时能量更容易以脂肪的形式蓄积,这些因素均与肥胖的形成有密切关系。但是目前对肠道梭菌在以下几个方面的作用仍未被阐明:1)梭菌是否是多糖水解酶的主要来源;2)多糖水解酶产生的短链脂肪酸对能量摄入的贡献;3)梭菌占优对细菌脂多糖的产生与吸收的影响;以及4)梭菌对FIAF表达的影响等。本文提出了可能的机制,为进一步的研究提供参考。     

学生早餐不可忽视(下)

二、早餐中摄入谷类食物的重要性 粮谷类食物是碳水化合物的主要来源,碳水化合物是我们机体最重要的能量来源,中国营养学会建议碳水化合物供能要占一天总能量的60％左右,蛋白质供能占10-14％,脂肪供能占25-30％。     

低卡路里的脂肪与油脂替代物在东方食品中的应用

尽管脂肪与油脂是人类所需的一种必需营养成分,是人体内能量的最大来源,但摄入过多亦是各种疾病的诱发因素。另外,人们不仅要求食品健康卫生,而且要求美味可口,这些通过食品新配料和新技术已经成为现实。直到近来,通过在食品里添加高甜度甜味剂与低能量填充剂,大大降低了食品里的卡路里含量。最先导入市场的是基于蛋白质与碳水化合物的新原料,它们能给食品水相带来一定的粘度,提供某些类似油脂的口感。最近,新异构化脂类与热稳定性好的合成脂品的开发成功,可使食品在显著减少卡路里与脂肪的情况下具有更多油脂的特征。这类脂肪替代物应用在…     

膳食脂质消化行径及其影响机制研究进展

膳食脂质是肌体能量、必需营养物质和生物活性成分的重要来源或载体,其在体内的消化行径往往受到消化场所及存在形态差异的影响。本文通过对膳食脂质在胃肠道内不同阶段的消化行径进行综述,分析膳食脂质在各阶段消化过程中的变化,阐明了膳食脂质在机体代谢过程中与脂肪酶、胆盐的亲和机制,以及小肠内的微生物菌群与膳食脂质在消化吸收中的相互作用,概述了不同类型、不同来源的膳食脂质间的消化差异。最后,本文总结了脂肪酸的链长及饱和程度、甘油三酯的结构、脂质的物理性质、乳化液滴的大小、界面性质及钙离子对膳食脂质体内消化的影响,以期为合理地摄入脂质、预防和治疗膳食脂质摄入过量引起的相关疾病提供依据,同时为研发功能结构脂及设计新型的含脂质食品提供参考。     

食品中抗肥胖成分的最新研究进展

随着生活方式的改变和饮食结构的变化,食物摄入量增加、能量支出减少和脂肪代谢紊乱造成肥胖和超重的流行。肥胖已经成为发展中国家的公共卫生问题,研究食品中的抗肥胖成分(如甘油二酯和共轭亚油酸)的作用机理,把抗肥胖功能性食品的开发集中于减少能量的摄入(如降低食品的能量密度或减少食物的摄入)或增加能量的消耗(促进新陈代谢),将成为食品研究与开发的重点。     

淀粉基脂肪替代物的研究应用概况

综述了淀粉为基质的脂肪替代物的研究进展及其应用。淀粉为基质的脂肪替代物包括以玉米淀粉、马铃薯淀粉、大米淀粉、木薯淀粉为原料的脂肪替代物,用于替代食品中的脂肪,可以安全有效地降低食品中的脂肪含量,从而减少总膳食能量和脂肪的过多摄入所带来的不利影响。     

广东省3岁及以上城市居民脂肪及脂肪酸摄入状况分析

目的 分析广东省城市居民的脂肪及脂肪酸的摄入水平与食物来源.方法 2017-2018年选取广东省5个城市,采用多阶段分层整群抽样方法抽取3岁及以上居民,运用非连续3 d 24 h回顾调查法收集调查对象膳食摄入信息.结果 广东省城市居民平均每日能量摄入量为1671.9 kcal,脂肪摄入为69.2 g,脂肪供能比为39....     

关于膳食指南的科学依据

文章阐述了膳食与健康的相互关系，说明只有按照科学原理调整膳食结构，使人体摄入的蛋白质、脂肪、能量、矿物质和维生素等各种营养成分达到平衡时，才能保证机体处于健康状态。     

食品中生物胺研究进展

生物胺的过量摄入会对人和动物机体造成严重毒害作用，为了解食品中生物胺对人体健康的影响，对食品中生物胺来源与影响因素以及生物胺代谢和毒性作用进行简要综述。     

脂肪替代品及其在肉制品中的应用

脂肪是三大营养素之一,在人体内发挥着重要的生理功能,但常摄入高脂肪膳食会对人体健康产生危害。脂肪替代品是一类被添加到低脂或无脂食品中,使它们具有与同类全脂食品相同或相近的感官效果,但所提供的能量降低的物质。阐述脂肪替代品的研究及其在肉制品中的应用现状,分析其中存在的问题,提出相应的解决对策,以期为脂肪替代品在肉制品中的进一步开发利用提供理论依据。     

蛋白质基质脂肪模拟物制备方法及其应用的研究进展

随着人们对饮食健康的关注日益增加,脂肪摄入过多带来的负面影响渐渐被人们正视。因此,脂肪替代品应运而生。脂肪模拟物作为脂肪替代品的一部分,由于其安全可靠得到了国内外的广泛研究。脂肪模拟物的制备是生产低脂食品的关键环节,目前蛋白质基质的脂肪模拟物主要通过物理方法、化学方法或者酶解法来制备,其应用主要在肉制品、乳制品、烘焙制品以及色拉调味品中。通过总结近年来国内外对脂肪模拟物的研究,对蛋白质基质脂肪模拟物的制备方法进行了分类阐述,并对不同的方法进行了分析和展望;对蛋白质基质脂肪模拟物的原料蛋白及其应用进行了较全面的总结。     

Invited review: Palmitic and stearic acid metabolism in lactating dairy cows

Energy is the most limiting nutritional component in diets for high-producing dairy cows. Palmitic (C16:0) and stearic (C18:0) acids have unique and specific functions in lactating dairy cows beyond a ubiquitous energy source. This review delineates their metabolism and usage in lactating dairy cows from diet to milk production. Palmitic acid is the fatty acid (FA) found in the greatest quantity in milk fat. Dietary sources of C16:0 generally increase milk fat yield and are used as an energy source for milk production and replenishing body weight loss during periods of negative energy balance. Stearic acid is the most abundant FA available to the dairy cow and is used to a greater extent for milk production and energy balance than C16:0. However, C18:0 is also intimately involved in milk fat production. Quantifying the transfer of each FA from diet into milk fat is complicated by de novo synthesis of C16:0 and desaturation of C18:0 to oleic acid in the mammary gland. In addition, incorporation of both FA into milk fat appears to be limited by the cow’s requirement to maintain fluidity of milk, which requires a balance between saturated and unsaturated FA. Oleic acid is the second most abundant FA in milk fat and likely the main unsaturated FA involved in regulating fluidity of milk. Because the mammary gland can desaturate C18:0 to oleic acid, C18:0 appears to have a more prominent role in milk production than C16:0. To understand metabolism and utilization of these FA in lactating dairy cows, we reviewed production and milk fat synthesis studies. Additional and longer lactation studies on feeding both FA to lactating dairy cows are required to better delineate their roles in optimizing milk production and milk FA composition and yield.     

Influence of lipase and/or emulsifier addition on the ileal and faecal nutrient digestibility in growing pigs fed diets containing 4% animal fat

Information on the addition of lipase and/or emulsifiers to less digestible or saturated fat sources, such as tallow or other animal fats, used in swine feeding is very limited. Therefore, in a 4 × 4 Latin square design, the effects of adding lipase (0.05% L5, microbial source) and/or an emulsifier (0.3% Lysoforte) on the apparent ileal (AID) and faecal (AFD) digestibility of the main nutrients and fatty acids in particular were studied with four ileal‐cannulated growing pigs (female, initial live weight 20 kg) fed diets containing barley/soybean meal supplemented with 4% animal fat. The fat source contained 35% saturated (S) and 65% unsaturated (U) fatty acids. All diets were free of antibacterial substances (antibiotics, copper sulphate or zinc oxide beyond requirements), in order to avoid interactions between the parameters studied and the gut flora. Lipase addition did not affect the AID or AFD of fat. However, the digestibility of minor fatty acids (C6:0, C14:0) was significantly improved by lipase at both ileal and faecal level. On the other hand, lipase supplementation (P < 0.05) improved the AID of dry matter (DM) and energy as well as the AFD of DM, organic matter (OM), crude protein (CP), ash and energy. Addition of an emulsifier did not have any significant influence on the AID or AFD of fat, while the AID values of DM, OM, CP and energy as well as the AFD values of DM, OM, CP and ash were significantly (P < 0.05) improved. Adding lipase in combination with an emulsifier to the diets decreased (P < 0.05) the AID and AFD of fat, with minor effects on the AID and AFD of the non‐fat components of the diet. The lack of improvement in the digestion of fat by exogenous lipase and/or emulsifier may be related to the rather high U/S ratio (0.65:0.35) of the animal fat source used and to the mode of incorporation of the emulsifier (no pre‐dispersion in the fat source). Furthermore, during the trial the diets, stored at room temperature, showed a steady increase in their content of free fatty acids (to more than 700 g kg^?1 fat), due to endogenous lipase activity, leaving less room for upgrading the digestion of animal fat by exogenous lipase and/or emulsifier. Copyright © 2004 Society of Chemical Industry     

The Effect of Inclusion of Naked Oats in the Concentrate Offered to Dairy Cows on Milk Production,Milk Fat Composition and Properties

Dairy cows in early or mid-lactation were offered naked oats- or barley-based concentrates in addition to ad libitum access to grass silage in a continuous design experiment of 10 weeks duration. Concentrates were formulated on an isonitrogenous basis and contained either 500 g barley or 565 g naked oats kg⁻¹ concentrates as the principal energy source in the concentrate. Concentrate type had no effect on silage intake, milk yield or milk protein concentration. However, nitrogen and modified acid detergent fibre digestibility were significantly reduced by inclusion of naked oats and this was reflected in a significant reduction in milk fat concentration. Milk fat from early lactation cows on the naked oats diet contained the highest proportion of unsaturated and the lowest proportion of saturated fatty acids. Sensory and instrumental analyses determined that this milk fat produced the softest, most spreadable butter. This was supported by solid fat content results. The degree of change in milk fat composition due to diet was similar irrespective of stage of lactation but milk fat compositions with the control treatment differed with stage of lactation. Dietary effects were established by the end of the first week of the trial and persisted for the 10-week trial period.     

Effect of dietary supplementation of sodium acetate and calcium butyrate on milk fat synthesis in lactating dairy cows

Acetate is a major source of energy and substrate for milk fat synthesis in the dairy cow. We recently reported a linear increase in milk fat yield and greater than a 30% net apparent transfer of acetate to milk fat with ruminal infusion of neutralized acetate. Additionally, ruminal acetate infusion linearly increases plasma β-hydroxybutyrate. The objective of the current study was to investigate the ability of acetate and butyrate fed in a diet to increase milk fat synthesis. Twelve multiparous lactating Holstein cows were randomly assigned to treatments in a 3 × 3 Latin square design with 14-d periods that included a 7-d washout followed by 7 d of treatment. Cows were fed ad libitum a basal diet with a low risk for biohydrogenation-induced milk fat depression, and treatments were mixed into the basal diet. Treatments were 3.2% NaHCO₃ (control), 2.9% sodium acetate, and 2.5% calcium butyrate (carbon equivalent to acetate treatment) as a percent of diet dry matter. Feeding sodium acetate increased dry matter intake by 2.7 kg, had no effect on milk yield, and increased milk fat yield by 90 g/d and concentration by 0.2 percentage units, compared with control. Calcium butyrate decreased dry matter intake by 2.6 kg/d, milk yield by 1.65 kg/d, and milk fat yield by 60 g/d, compared with control. Sodium acetate increased concentration and yield of 16 carbon mixed source fatty acids (FA) and myristic acid, while decreasing the concentration of preformed FA, compared with control. Calcium butyrate had no effect on concentration of milk FA by source, but increased concentration of trans-10 C18:1 in milk by 18%, indicating a shift in rumen biohydrogenation pathways. Our data demonstrate that milk fat yield and concentration can be increased by feeding sodium acetate at 2.9% of diet dry matter, but not by feeding calcium butyrate at an equivalent carbon mass.     

不同比例碳水化合物和油脂饮食对机体代谢和健康影响的研究进展

碳水化合物和油脂是人体重要的能量来源,饮食中必须保证足够的脂肪和碳水化合物。高脂、高碳水化合物饮食能够提供丰富营养,同时也会诱发脂肪肝、肥胖、心血管疾病、高血糖、高血脂以及影响子代发育等。综述了不同比例碳水化合物和油脂饮食对脂肪代谢、糖代谢、繁殖发育等方面影响,并介绍了植物提取物对不同比例油脂与碳水化合物饮食引起的疾病的治疗作用,以期为人们合理膳食提供参考。     

婴儿配方乳粉脂质母乳化的研究进展

人乳脂肪是最复杂的天然脂质混合物之一,具有独特的脂肪酸组成、分布和许多复杂脂质。乳脂肪几乎提供着新生婴儿所需的一半能量,同时还会影响婴儿日后的代谢方式和整体发育。因此,随着对母乳脂肪及婴儿生长需求研究的深入,以母乳脂质组成为模板,对婴儿配方乳粉脂质进行母乳化模拟,可以缩小母乳与婴儿配方乳粉喂养婴儿之间的差异。目前,婴儿配方乳粉脂质母乳化主要集中在脂肪酸组成模拟、sn-2棕榈酸结构脂的应用以及乳脂肪球膜成分的添加方面。另外,利用乳脂肪球膜包裹脂滴实现脂肪球结构模拟的相关研究也在逐步开展。本文着重对这几个方面的研究进展进行总结,在关注婴儿营养需求的同时,为婴儿配方乳粉的研发提供理论依据。     

我国食用油脂加工研究进展及发展对策

分析食用油脂加工着新进展,提出食用油脂加工存在的加工工艺落后、加工装备简单且能耗高、加工过程不规范等问题,并从食用油脂加工理念、加工工艺、加工装备和开发新型食用油脂等方面探讨了提升我国食用油脂加工水平的对策。     

Dietary Energy Value of Medium-chain Triglycerides

As a fat source in our diet, medium-chain triglycerides (MCTs) result in lower fat deposition when compared by 2 methods to long-chain triglycerides. Using data from 10 animal studies, the calculated energy loss during utilization of MCTs was 16%, resulting in a net energy value (NEV) of 6.97 kcal/g. The NEV calculated from the molecular composition of 9 MCTs with widely varying caprylic:capric fatty acid ratios was 6.72 ± 0.16 kcal/g. For 5 MCTs with completely defined fatty acid compositions, the NEV was 6.80 ± 0.15 kcal/g. Establishing the NEV for dietary MCTs at 6.8 kcal/g is proposed.