不同膳食脂肪酸对大鼠乳腺癌组织脂肪酸组成和脂代谢基因表达的影响

目的探讨不同膳食脂肪酸组成影响大鼠乳腺癌发生、发展的可能分子机制。方法用8种不同膳食脂肪酸组成(SFA、MUFA、n-6PUFA、n-3PUFA、1∶1n-6/n-3、5∶1n-6/n-3、10∶1n-6/n-3、1∶2∶1S/M/P其中n-6/n-31∶1)喂养SD雌性大鼠,并在大鼠乳腺癌模型的基础上,用气相色谱内标法观察大鼠乳腺组织脂肪酸组成改变,RT-PCR分析组织脂代谢调控基因(FAS、COX-2和5-LOX)的表达。结果在不同膳食脂肪酸构成中,只有1∶1n-6/n-3能有效抑制大鼠乳腺癌的发生。不同膳食脂肪酸构成可导致大鼠乳腺组织脂肪酸组成发生相应变化,且各组间的脂肪酸含量有显著差异。高乳腺癌诱发的SFA、MUFA、n-6PUFA、5∶1n-6/n-3、10∶1n-6/n-3和1∶2∶1S/M/P喂养组乳腺组织含有较多的C18∶1、C18∶2和C20∶4,而EPA和DHA含量极少。无或低乳腺癌诱发的n-3PUFA和1∶1n-6/n-3喂养组乳腺组织EPA和DHA明显增多,C20∶4含量显著减少。RT-PCR结果显示1∶1n-6/n-3低诱癌组较相应对喂组上调FAS、COX-2和5-LOXmRNA表达力度明显弱于其它高乳腺癌诱发组。结论不同膳食脂肪酸组成能明显改变大鼠乳腺组织脂肪酸组成,进而影响脂代谢基因FAS、COX-2和5-LOX表达,可能是大鼠乳腺癌发生的分子机制之一。     

膳食脂肪酸对正常和携瘤小鼠血浆脂肪酸谱的影响

目的研究膳食中的脂肪酸对正常和携瘤小鼠血浆脂肪酸谱的影响并研究肿瘤代谢是否影响血浆脂肪酸谱。方法正常(无瘤)鼠和携瘤鼠在两个独立的实验中分别进行。每个实验均包含普通餐和4种高脂餐。这些高脂餐均含20%(质量比w/w)的脂肪,因脂肪来源的不同而分别富含饱和脂肪酸(SFA,月桂酸C12:0和肉豆蔻酸C14:0),单不饱和脂肪酸(MUFA,油酸C18:1),n-6多不饱和脂肪酸(n-6PUFA,亚油酸C18:2)和n-3多不饱和脂肪酸(n-3PUFA,亚麻酸C18:3)。在正常鼠实验中,20只雄性Balb/C小鼠被随机分成普通饲料对照(NC)组和4个高脂餐组(即SFA组、MUFA组、n-6PUFA组、n-3PUFA组),用相应的饲料喂养6w。在另一实验中,48只雄性Balb/C裸鼠被随机分成2个正常饲料组和4个高脂餐组。将Mia Pa Ca2人胰腺癌细胞移植到除一个普通饲料组外的5组裸鼠皮下。将6组动物用相应的饲料喂养7w。每一实验结束后,用气相色谱的方法分析血浆脂肪酸谱的变化。结果以普通餐组为对照组,血浆脂肪酸变化如下:(1)在无瘤和携瘤两种状态下,属于SFA的C12:0和C14:0含量在SFA组增高(P0.01)而属于MUFA的C18:1在MUFA组增高(P0.01)。(2)在无瘤状态下,属于n-6PUFA的C18:2在n-6PUFA组没有显著变化(P0.05),且与n-3PUFA组相比还有降低。而在携瘤状态下,C18:2的含量在n-6PUFA组却有增高趋势。(3)在无瘤和携瘤两种状态下,属于n-3PUFA的C18:3的含量在n-3PUFA组增高(P0.01)。结论 1.当无瘤鼠进食4种高脂餐时,餐中富含的SFA,MUFA和n-3PUFA可在血浆中增高,而餐中富含的n-6PUFA则不高。2.携瘤鼠对实验餐的反应与无瘤鼠大体相同,但n-6PUFA高脂餐也可增进携瘤鼠血浆中的n-6PUFA。3.癌细胞对n-6PUFA代谢的影响导致了血浆n-6PUFA在无瘤和携瘤鼠间的差异,该差异可能对癌症的诊断和治疗有所帮助。     

不同膳食脂肪酸构成影响MNU诱导大鼠乳腺肿瘤发生的研究

目的:探讨不同膳食脂肪酸对甲基亚硝基脲(MNU)诱导的大鼠乳腺肿瘤发生的影响。方法:用含15%脂肪(wt/wt)的半合成饲料喂养雌性SD大鼠。大鼠50d龄时,分8组喂养8种不同膳食脂肪酸组成的饲料,即SFA、MUFA、n-6PUFA、n-3PUFA、1∶1n-6/n-3、5∶1n-6/n-3、10∶1n-6/n-3和S/M/P为1∶2∶(1其中n-6/n-3为1∶1),每组又分肿瘤组和对喂组,肿瘤组,单次腹腔注射MNU(50mg/kgbw),相应的对喂组注射生理盐水,持续喂养18w。观察各组大鼠体重增长、乳腺肿瘤发生率、肿瘤多发率及肿瘤潜伏期等。结果:除喂养n-3PUFA的大鼠在实验6w后出现体重增长受阻外,其它组别的大鼠体重增长无明显差异。各对喂组大鼠均无乳腺肿瘤发生,而在MNU注射组中,喂养n-3PUFA的大鼠也无乳腺肿瘤发生,但喂养SFA、MUFA、n-6PUFA、5∶1n-6/n-3、10∶1n-6/n-3和S/M/P(1/2/1)大鼠乳腺肿瘤诱发率是1∶1n-6/n-3的2倍,且喂养1∶1n-6/n-3的大鼠,其肿瘤发生的潜伏期也最长。结论:不同膳食脂肪酸构成对MNU诱导的大鼠乳腺肿瘤发生影响不同。,1∶1n-6/n-3膳食脂肪酸构成能有效抑制MNU诱导的乳腺肿瘤发生。     

膳食脂肪酸对胰腺癌小鼠骨骼肌和肝脏细胞中脂肪酸构成的影响（英文）

目的探讨含不同类型脂肪酸的高脂膳食对荷胰腺癌小鼠骨骼肌和肝脏细胞中脂肪酸构成的影响。方法将60只健康5w龄雄性C57BL/6裸鼠随机分为6组:饱和脂肪酸(SFA)组、单不饱和脂肪酸(MUFA)组、n-6多不饱和脂肪酸(n-6 PUFA)组、n-3多不饱和脂肪酸(n-3 PUFA)组、等能量对照(ISO-C)组和正常对照(NC)组。四个高脂膳食组用四种高脂(15%g/100g)饲料分别喂养,其油脂来源分别为椰子油(富含SFA),橄榄油(富含MUFA),大豆油(富含n-6 PUFA)和亚麻籽油(富含n-3 PUFA)。ISO-C组和NC组的饲料含4%⁵%的大豆油。各组裸鼠在用各自的试验饲料喂养1w后,将HPAF-Ⅱ胰腺癌细胞接种到胰腺内,继续该饲料喂养至第14w末。处死小鼠,取股四头肌和肝组织,用气相色谱-质谱联用仪分析脂肪酸构成。结果骨骼肌和肝脏的脂肪酸构成在ISO-C组和NC组之间大致相同,以ISO-C组为对照组,我们发现小鼠骨骼肌脂肪酸的变化如下:(1)属于饱和脂肪酸的棕榈酸(C16:0)、十七烷酸(C17:0)、硬脂酸(C18:0)和花生酸(C20:0)的含量在SFA组增高(P<0.05);(2)属于单不饱和脂肪酸的油酸(C18:1)的含量在MUFA组增高(P<0.05);(3)属于n-6多不饱和脂肪酸的γ-亚麻酸(γC18:3)的含量在n-6 PUFA组增高(P<0.05);(4)属于n-3多不饱和脂肪酸的亚麻酸(C18:3)、二十碳五烯酸(C20:5)和二十二碳五烯酸(C22:5)的含量在n-3 PUFA组增高(P<0.05)。小鼠肝脏脂肪酸的构成结果显示:(1)饱和脂肪酸的含量在SFA组没有增高;(2)单不饱和脂肪酸中仅二十烯酸(C20:1)的含量在MUFA组增高(P<0.05);(3)n-6多不饱和脂肪酸二十碳二烯酸(C20:2)和花生四烯酸(C20:4)的含量在n-6 PUFA组增高(P<0.05);(4)亚麻酸(C18:3)、二十碳五烯酸(C20:5)、二十二碳五烯酸(C22:5)和二十二碳六烯酸(C22:6)的含量在n-3 PUFA组均增高(P<0.05)。结论荷瘤小鼠进食由不同类型脂肪酸组成的高脂膳食后,骨骼肌脂肪酸的构成反映了饲料脂肪酸的构成,而肝脏脂肪酸的构成与饲料脂肪酸的构成仅部分相同。     

中国成人膳食脂肪酸摄入和食物来源状况分析

目的分析我国成人膳食脂肪酸摄入量及主要脂肪酸的食物来源。方法利用2002年中国居民营养与健康状况调查中3d24h回顾膳食调查结果,结合食物成分表中脂肪酸数据及补充测定的34种食物脂肪酸数据,对44905名成人(不包括孕妇和乳母)的膳食脂肪酸摄入量及食物来源进行分析。结果城市居民饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA)摄入量中位数分别为15.9、23.6和20.2,农村居民分别为13.8、23.4和13.7g/d;城市居民α亚麻酸(ALA)、二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)、亚油酸(LA)和花生四烯酸(AA)摄入量中位数分别为2.3g/d、1.8mg/d、22.1mg/d、17.6g/d、45.4mg/d,农村居民分别为1.3g/d、0.0mg/d、6.0mg/d、11.3g/d、43.1mg/d。城市、农村居民膳食中S/M/P比值分别为1:1.4:1.3和1:1.5:1.1;n-6/n-3系列多不饱和脂肪酸比例分别为7.6和8.0。全国居民SFA、MUFA和PUFA供能百分比中位数分别为6.1、9.8和6.3。城市居民51.4%的膳食SFA来自动物性食物,农村为38.5%。城市和农村居民膳食中MUFA的主要来源是食用油和动物性食物。城市居民膳食脂肪中约50%的PUFA、n-6PUFA和n-3PUFA来自于豆油和色拉油;农村PUFA和n-6系列PUFA来源广泛。农村居民膳食n-3PUFA近一半来自于菜籽油。结论城乡居民SFA、MUFA、PUFA的摄入比例合理;与参考摄入量相比,城乡居民n-6/n-3PUFA比例偏高,应增加膳食中n-3系列PUFA摄入量所占比例。     

补充Cr~(3+)和Mg~(2+)对胰岛素抵抗人群血清脂肪酸的影响

目的补充铬(Cr3+)和镁(Mg2+)对胰岛素抵抗人群血清脂肪酸组成的影响。方法将120名年龄45~59岁的胰岛素抵抗人群随机分为对照、铬、镁、铬+镁共4组,分别给予安慰剂、铬160μg/d、镁200 mg/d、铬160μg/d+镁200 mg/d补充干预,为期3月。干预前后分别抽取静脉血并分离血清,气相色谱法分析血清脂肪酸组成。结果各组与干预前相比,单独补充镁或铬和镁联合补充可以降低棕榈油酸、二十碳三烯酸所占总脂肪酸百分比,提高n-3多不饱和脂肪酸(PUFA)占总脂肪酸百分比,但差异不具显著性;单独补充镁或铬和镁联合补充可以显著降低n-6/n-3PUFA比值(P0.05);饱和脂肪酸含量干预前后没有明显变化。各干预组与对照组相比,脂肪酸组成差异没有统计学意义。结论镁或铬联合镁补充可以通过降低棕榈油酸、二十碳三烯酸,提高n-3 PUFA含量,降低n-6/n-3 PUFA比值改善胰岛素抵抗状态。     

广州成人膳食n-6/n-3脂肪酸比值与心血管疾病危险因素的关系

目的分析广州40～65岁居民膳食n-6/n-3脂肪酸比值与心血管疾病危险因素的关系。方法 40～65岁广州市民1133人,采用定量食物频数问卷调查对象的每日摄入食物种类和数量,计算能量和营养素摄入量,检测其红细胞膜脂肪酸构成、血脂及颈动脉内中膜厚度(IMT),分析n-6/n-3比值大小高Q3,中Q2,低Q1与血压、血脂和IMT的关系。结果 995人资料完整纳入分析。对象日均膳食总能量摄入为9.10±2.09MJ、脂肪供能比为(34.3±7.9)%。膳食n-6/n-3脂肪酸比值为(29.74±22.71):1,红细胞膜n-6/n-3脂肪酸比值为(2.7±1.0):1,膳食SFA:MUFA:PUFA为1:1.5:1。膳食n-3脂肪酸摄入量与红细胞膜n-3构成比、膳食n-6/n-3比值与红细胞膜n-6/n-3比值均呈显著正相关关系。膳食n-6/n-3比值最高组Q3(>31.16)对象的收缩压、TC和IMT水平显著高于最低组Q1(<17.40);红细胞膜n-6/n-3比值最高组Q3(>3.04)和中间组Q2(2.18～3.03)对象的收缩压、舒张压、TC、LDL-C及IMT水平均显著高于最低组Q1(≤2.17)。结论广州市40～65岁居民膳食n-6/n-3脂肪酸比值约为30:1;该比值小于17.40:1时,有较低的血压,总胆固醇及IMT水平。     

多不饱和脂肪酸不同配比对大鼠血脂影响

目的 研究不同n-3/n-6配比的多不饱和脂肪酸(PUFA)对大鼠血脂影响。方法 将58只SD大鼠根据血清总胆固醇(TC)水平随机分为6组,分别给予基础饲料、高脂饲料和添加n-3/n-6不同配比PUFA的高脂或基础饲料。于第15,30,45 d分别测血脂水平,第45 d取脂肪组织称重并测肝组织中过氧化物酶体增殖物激活受体γ(PPAR-γ)和腺苷酸活化蛋白激酶α2(AMPK-α2)的mRNA表达。结果 摄入添加PUFA膳食的4组大鼠45d后血清甘油三酯(TG)分别为(1.15±0.37),(1.25±0.56),(1.00±0.25),(1.17±0.30)mmol/L,均明显低于高脂组的(1.73±0.33)mmol/L;TC分别为(1.80±0.18),(1.89±0.20),(1.41±0.21),(1.58±0.16)mmol/L,均明显低于高脂组的(2.23±0.19)mmol/L;低密度脂蛋白胆固醇(LDL-C)分别为(1.00±0.23),(1.25±0.18),(1.06±0.13),(1.25±0.14)mmol/L,均明显低于高脂组的(1.53±0.27)mmol/L;其脂体比、PPAR-γmRNA、AMPK-α2mRNA表达量均明显高于高脂组,差异均有统计学意义(P<0.05)。结论 PUFA改善大鼠高血脂并降低脂肪积累,可能与肝组织AMPK和PPAR-γ等脂肪酸氧化基因表达增加有关。     

中国黄海海域部分海鱼脂肪酸含量分析

目的分析中国黄海海域部分可食用海鱼的脂肪酸含量。方法于青岛市大型水产批发市场采集我国黄海海域38种海鱼样品,提取脂肪后甲酯化,以气相色谱法分析其脂肪酸含量。结果 38种海鱼总脂含量范围为0.459(鲬鱼)~17.086 g/100 g(海鲫)。海鱼中含量最多的饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)、n-6和n-3多不饱和脂肪酸(PUFA)分别为C16∶0、C18∶1n9、C20∶4n6和C22∶6n3。SFA总量范围为44.5(黄线狭鳕)~2442.9 mg/100 g(海鲫),P50=345.6 mg/100 g;MUFA总含量范围为19.8(黄线狭鳕)至2753.5 mg/100 g(青鳞鱼),P50=242.3 mg/100 g;n-6PUFA总量范围9.5 mg/100 g(黄线狭鳕)~939.5(梭鱼),P50=42.5 mg/100 g;总n-3PUFA含量范围为84.3(鲬鱼)~1452.2 mg/100 g(海鲫),P50=324.3 mg/100 g。n-3PUFA、EPA和DHA的含量均与总脂含量呈正相关(P0.001)。结论黄海海域大多数海鱼的不饱和脂肪酸含量丰富且具有种属差异性,可以作为n-3不饱和脂肪酸的良好来源。     

中国三地区人成熟母乳脂肪酸含量的研究

目的分析中国处于三个不同地理环境地区的母体成熟乳中脂肪酸含量的差异。方法选取江苏句容(河湖地区)、山东日照(沿海地区)和河北徐水(内陆地区)三地,每地区募集40～50名健康产妇,于产后第28天采集母乳,Folch法提取其中脂肪,气相色谱法分析其中31种脂肪酸构成及含量。结果句容,日照和徐水分别募集到47、50和46名受试者,各地成熟乳中饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)、n-6多不饱和脂肪酸(n-6PUFA)和n-3多不饱和脂肪酸(n-3PUFA)的主要成份均分别为C16∶0、C18∶1 n-9cis、C18∶2 n-6 cis和C18∶3 n-3。三地区成熟乳中花生四烯酸(ARA)百分含量中位数分别为0.72%、0.63%和0.63%;二十二碳六烯酸(DHA)分别为0.41%、0.47%和0.24%。三地区总乳脂含量中位数分别为4.47、1.50和3.91g/100g母乳;其总脂肪酸含量中位数分别为3934、1319和3437mg/100g母乳,日照总乳脂含量和总脂肪酸含量显著低于另两地区。结论母体成熟乳中脂肪酸含量及构成存在显著地区差异性。     

Palmitic and stearic acids similarly affect plasma lipoprotein metabolism in cynomolgus monkeys fed diets with adequate levels of linoleic acid

This study was designed to evaluate whether the exchange of specific saturated fatty acids [SFA; palmitic acid (16:0) for stearic acid (18:0)] would differentially affect plasma lipids and lipoproteins, when diets contained the currently recommended levels of total SFA, monounsaturated fatty acids and polyunsaturated fatty acids (PUFA). Ten male cynomolgus monkeys were fed one of two purified diets (using a cross-over design) enriched either in 16:0 (palmitic acid diet) or 18:0 (stearic acid diet). Both diets provided 30% of energy as fat (SFA/monounsaturated fatty acid/PUFA: 1/1/1). The palmitic acid and stearic acid diets were based on palm oil or cocoa butter (59% and 50% of the total fat, respectively). By adding different amounts of sunflower, safflower and olive oils, an effective exchange of 16:0 for 18:0 of approximately 5% of energy was achieved with all other fatty acids being held constant. Monkeys were rotated through two 10-wk feeding periods, during which time plasma lipids and in vivo lipoprotein metabolism (following the simultaneous injection of (131)I-LDL and (125)I- HDL were evaluated). Plasma triacyglycerol (0.40 +/- 0.03 vs. 0.37 +/- 0.03 mmol/L), plasma total cholesterol (3.59 +/- 0.18 vs. 3.39 +/- 0.23 mmol/L), HDL cholesterol (1.60 +/- 0.16 vs 1.53 +/- 0.16 mmol/L) and non-HDL cholesterol (2.02 +/- 0.26 vs. 1.86 +/- 0.23 mmol/L) concentrations did not differ when monkeys consumed the palmitic acid and stearic acid diets, respectively. Plasma lipoprotein compositional analyses revealed a higher cholesteryl ester content in the VLDL fraction isolated after consumption of the stearic acid diet (P < 0.10), as well as a larger VLDL particle diameter (16.3 +/- 1.7 nm vs. 13.8 +/- 3.6 nm; P < 0.05). Kinetic analyses revealed no significant differences in LDL or HDL transport parameters. These data suggest that when incorporated into diets following current guidelines, containing adequate PUFA, an exchange of 16:0 for 18:0, representing approximately 11 g/(d.10.46 mJ) [ approximately 11 g/(d.2500 kcal)] does not affect the plasma lipid profile and has minor effects on lipoprotein composition. Whether a similar effect would occur in humans under comparable dietary conditions remains to be established.     

Conjugated linoleic acid supplementation for 8 weeks does not affect body composition, lipid profile, or safety biomarkers in overweight, hyperlipidemic men

The usefulness of conjugated linoleic acid (CLA) as a nutraceutical remains ambiguous. Our objective was, therefore, to investigate the effect of CLA on body composition, blood lipids, and safety biomarkers in overweight, hyperlipidemic men. A double-blinded, 3-phase crossover trial was conducted in overweight (BMI ≥ 25 kg/m(2)), borderline hypercholesterolemic [LDL-cholesterol (C) ≥ 2.5 mmol/L] men aged 18-60 y. During three 8-wk phases, each separated by a 4-wk washout period, 27 participants consumed under supervision in random order 3.5 g/d of safflower oil (control), a 50:50 mixture of trans 10, cis 12 and cis 9, trans 11 (c9, t11) CLA:Clarinol G-80, and c9, t11 isomer:c9, t11 CLA. At baseline and endpoint of each phase, body weight, body fat mass, and lean body mass were measured by DXA. Blood lipid profiles and safety biomarkers, including insulin sensitivity, blood concentrations of adiponectin, and inflammatory (high sensitive-C-reactive protein, TNFα, and IL-6) and oxidative (oxidized-LDL) molecules, were measured. The effect of CLA consumption on fatty acid oxidation was also assessed. Compared with the control treatment, the CLA treatments did not affect changes in body weight, body composition, or blood lipids. In addition, CLA did not affect the β-oxidation rate of fatty acids or induce significant alterations in the safety markers tested. In conclusion, although no detrimental effects were caused by supplementation, these results do not confirm a role for CLA in either body weight or blood lipid regulation in humans.     

Dietary conjugated linoleic acid reduces lipid peroxidation by increasing oxidative stability in rats

The antioxidative effect of conjugated linoleic acid (CLA) was examined by determining lipid peroxidation and antioxidative enzyme activities. Male Sprague-Dawley rats were fed one of the experimental diets-normal diet, vitamin E-deficient control diet, 0.5% CLA vitamin E-deficient diet, or 1.5% CLA vitamin E-deficient diet for 5 wk. Hepatic thiobarbituric acid reactive substances (TBARS) were increased in the vitamin E-deficient control group, but they were was significantly lowered in the CLA groups. Similarly, hepatic glutathione peroxidase activity was increased in the vitamin E-deficient diet and reduced by CLA supplementation. In addition, CLA caused a significant decrease in superoxide dismutase activity while having no effect on catalase activity. Analyses of the fatty acid composition revealed that dietary CLA was incorporated into hepatic microsomal membrane dose-dependently. Compared to the vitamin E-deficient control, CLA resulted in significantly higher saturated and monounsaturated fatty acids (palmitic and oleic acids) while lowering levels of oxidation-susceptible polyunsaturated fatty acids (linoleic, linolenic, and arachidonic acids) in both plasma and hepatic membrane. The concentrations of plasma cholesterol and triacylglycerol (TG) were lower in the 1.5% CLA group than in other groups. These results suggest that dietary CLA has antiatherosclerotic and antioxidant activity by increasing oxidative stability in plasma and hepatic membrane in the vitamin E-deficient rats.     

Conjugated linoleic acid and human health-related outcomes

Summary There has been increasing interest in health benefits of conjugated linoleic acid (CLA) based on findings with laboratory animals. Some human studies have also suggested health benefits of CLA, but because of the mixes used these could not be readily associated with a particular isomer of CLA. A recent study examined the separate effects of near‐pure cis‐9,trans‐11 CLA (c9,t11 CLA) or trans‐10,cis‐12 CLA (t10,c12 CLA) on health‐related outcomes in healthy young males. The CLA isomers were provided in capsules and at three doses (up to about 2.5 g/day) each for 8 weeks. Both c9,t11 and t10,c12 CLA were incorporated in a dose–response fashion into blood lipids and cells. At the doses and durations used, neither isomer of CLA affected bodyweight, body mass index or body composition, insulin sensitivity, immune function or markers of inflammation. However, at the doses and durations used, c9,t11 and t10,c12 CLA had opposing effects on blood lipid concentrations. Altered dairy cow‐feeding practices were used to produce c9,t11 CLA‐rich milk and, from this ultra heat‐treated milk, cheese and butter were produced. The milk and the dairy products made from it had ninefold higher contents of c9,t11 CLA, higher contents of n‐3 fatty acids and lower contents of total fat and of saturated fatty acids. They also contained much higher contents of trans‐vaccenic acid (tVA). The modified dairy products were used in a 6‐week controlled dietary intervention study in healthy middle‐aged males. c9,t11 CLA and tVA were incorporated from dairy products into blood lipids and cells. Consumption of the CLA‐rich (and tVA‐rich) dairy products did not affect bodyweight or body mass index, insulin sensitivity or inflammatory markers. However, there were some detrimental effects on blood lipids. These effects may be due to tVA rather than to c9,t11 CLA, as they are consistent with the effects of trans fatty acids and not consistent with the effects of c9,t11 CLA identified in the earlier study with c9,t11 CLA in capsules.     

Changes in dietary lipid saturation modify fatty acid composition and high-density-lipoprotein binding of adipocyte plasma membrane

Binding of rat high-density lipoprotein (HDL) to adipocyte plasma membranes appears to be mediated by specific protein-recognition sites, but membrane lipids may also affect these interactions. To study the effect of dietary fatty acid composition on adipocyte-membrane phospholipid composition and HDL binding, male Wistar rats (250 +/- 10 g) were fed diets high in polyunsaturated (20% wt:wt sunflowerseed oil) or saturated and monounsaturated fatty acids (20% lard, by weight). Sunflower-oil vs lard feeding significantly increased the polyunsaturated fatty acid content of membrane diacylglycerophospholipids and the (22:0 and 24:0) content of long-chain fatty acids of sphingomyelin (p less than 0.05) from epididymal and perirenal adipocyte plasma membranes. Concomitant with these changes in membrane phospholipid composition, sunflower-oil vs lard treatment significantly increased the maximum binding capacity (Bmax) of 125I-labeled HDL2 (p less than 0.05). These results show that feeding polyunsaturated fatty acids enhanced HDL2 Bmax of adipocyte plasma membranes, possibly as a consequence of altering the fatty acid composition of membrane phospholipids.     

Linoleic acid conjugation by human intestinal microorganisms is inhibited by glucose and other substrates in vitro and in gnotobiotic rats

The anticarcinogen conjugated linoleic acid (CLA) is a product of bacterial activity that isomerizes linoleic acid (LA) in the rumen of herbivores. Therefore, fatty dairy products in the human diet are enriched with CLA. Although bacteria capable of in vitro LA conjugation were detected in the human intestinal tract, CLA synthesis from dietary sunflower seed oil was not observed in gnotobiotic rats associated with these intestinal bacteria. The objective of the study was to investigate variables that affect LA conjugation. In vitro, LA conjugation was strongly inhibited by glucose and other substrates. Concentrations of 1.5 mmol glucose/L inhibited LA conjugation by 50%. Methyl-alpha-D-glucoside was a less effective inhibitor than glucose, and 2-deoxy-D-glucose did not inhibit LA conjugation at all. To analyze the concentration of carbohydrates in intestinal contents, the LA-conjugating bacterial mixed culture and human fecal microorganisms were introduced into germ-free rats. Samples of feces and cecum and colon contents of both groups exhibited in vitro LA-conjugating activity. Rats associated with human intestinal microorganisms contained 5.7 +/- 1. 3 mmol glucose/L in the cecal contents and 6.6 +/- 1.0 mmol glucose/L in the colonic contents. Rats associated with CLA-producing bacterial culture contained 3.4 +/- 1.3 mmol glucose/L in the cecal contents and 4.2 +/- 1.0 mmol glucose/L in the colonic contents. These values are within a range that may explain the observed inhibition of LA conjugation in vivo.     

The metabolic conversion of 9,11,13-eleostearic acid (18:3) to 9,11-conjugated linoleic acid (18:2) in the rat

The presence of a significant amount of 9,11-conjugated linoleic acid (CLA, 9,11-18:2) was confirmed in the liver and plasma lipids of rats fed a 1% (w/w % of diet) eleostearic acid (ESA, 9,11,13-18:3) diet for 4 wk. The chemical structure of the 9,11-CLA apparent in the tissue lipids was identified by gas chromatography-electron impact mass spectrometry after its conversion to a 4,4-dimethyloxazoline derivative. The concentration of CLA in the total fatty acids of the liver and plasma lipids reached to about 1%, for each in the CLA-supplemented rats, while reaching 3.2% and 2.5%, respectively, in the ESA-supplemented rats. The results suggest that alpha-ESA is metabolized partially to CLA via a delta 13-saturation reaction in the rat. Some biological activities observed in alpha-ESA-fed animals may be ascribed also to CLA that is formed from ESA in the body.     

大豆异黄酮和皂甙对糖尿病大鼠抗动脉粥样硬化活性的研究

目的　研究大豆异黄酮和皂甙 (SPE)对糖尿病大鼠血糖、血脂、血浆脂蛋白脂质过氧化及血小板聚集活性的影响。方法　取 16只GK/Jcl雄性大鼠 (2型糖尿病模型 ) ,随机分为 2组 :对照组喂普通饲料 ,实验组喂添加 2 0g/kgSPE的饲料 2 0周 ,观察血液生化指标的变化。血浆脂蛋白采用序列超速离心分离法分离。结果　喂饲SPE的糖尿病大鼠血糖为 (11 9± 0 9)mmol/L ,动脉粥样硬化指数为 0 4 0± 0 14 ,血浆过氧化脂质水平为 (15 7± 0 5 )mmol/L ;未喂饲SPE的对照组糖尿病大鼠上述指标分别为 (14 2± 2 0 )mmol/L、0 5 8± 0 2 2和 (2 0 7± 3 0 )mmol/L ,差异有显著意义。由ADP和胶原蛋白诱导的血小板聚集率两组分别为 (5 4 1± 8 8) %和 (5 8 0± 7 9) %、(6 6 6±12 4 ) %和 (6 9 6± 9 4 ) % ,差异有显著意义。结论　SPE具有明显的降低血糖、改善动脉粥样硬化指数、抑制脂质过氧化和血小板聚集的作用 ,对大鼠糖尿病及其动脉粥样硬化并发症的发生可起到积极的预防和控制作用。     

Occurrence and biochemical characteristics of natural bioactive substances in bovine milk lipids

Bovine milk lipids (BML) contain a number of bioactive substances with positive as well as negative properties, mainly in the class of fatty acids. Besides trans fatty acids (TFA), conjugated linoleic acids (CLA) are of particular interest. Apart from ruminant meat products the main source of CLA in food are BML. Although TFA as well as saturated fatty acids (12:0-16:0) are thought to be positively correlated with atherosclerosis and coronary heart disease, CLA are considered antiatherogenic. Further, CLA are reported to reduce adipose fat and to have anticarcinogenic properties. The varying CLA and TFA contents of lipids from milk and dairy products are positively correlated with one another. However, TFA are also negatively correlated with 12:0-16:0 in BML. Anticarcinogenic effects are also ascribed to butyric acid as well as to some phospholipids and ether lipids present in BML. Moreover, the essential fatty acids 18:2n-6 and 18:3n-3 are found in BML which are involved in a variety of biochemical processes and thus have numerous functions in human metabolism. Contents of the individual bioactive components of BML are summarised taking into account also seasonal variations. The total content of bioactive substances in BML is approximately 75 % but their overall impact on human health considering benefits and drawbacks is difficult to assess.     

Fish oils in hypertriglyceridemia: a dose-response study

The effects of three supplemental doses of fish oil on plasma lipids, lipoproteins, and bleeding times were studied in ten hypertriglyceridemic patients. After a 3-wk baseline period each patient was given 15, 25, or 40 mL fish oil/d (containing 4.5, 7.5, and 12 g n-3 fatty acids) for three successive 6-wk periods, each separated by a 4-wk period of no supplementation. Plasma cholesterol concentrations decreased from 7.40 mmol/L to 6.35, 6.55, and 6.40 mmol/L with increasing doses of fish oil (p less than 0.01 vs baseline for each). Plasma triglyceride concentrations decreased from 6.10 mmol/L to 2.90, 2.80, and 2.35 mmol/L (p less than 0.01 vs baseline for each). Low-density-lipoprotein cholesterol concentrations increased significantly (by 23% and 28%) with the two higher doses, respectively. Bleeding times increased only with the largest dose. The lowest dose was the most hypolipidemic per gram n-3 fatty acids.