124n—3系多不饱和脂肪酸与健康

ｎ－３系多不饱和脂肪酸具有防治心血管疾病、促进脑组织及视网膜的正常生长发育等生理作用，因此越来越引起人们摄取的兴趣。本从目前的膳食结构以及ｎ－３系多不饱和脂肪酸的生理作用阐述了摄取ｎ－３系多不饱和脂肪酸的必要性，并对ｎ－３系多不饱和脂肪酸的来源、摄取剂量、副作用以及需注意的问题等进行了探讨。     

鱼油对小鼠脑磷脂中脂酸组成的影响

昆明种小鼠随机分成两组，对照组和鱼油组，按小鼠处死时间，对照组分三个亚组，鱼油组分四个亚组。取小鼠脑组织，采用气相色谱法测其脑磷脂中脂肪酸组成，考察鱼油中ｎ－３系多不饱和脂肪酸对小鼠大脑的影响，结果表明：鱼油可使小鼠脑重增加（Ｐ＜０．０５），使脑磷脂中饱和脂肪酸，单不饱和脂肪酸和ｎ－６系多不饱和脂肪酸水平降低，使ｎ－３系多不饱和脂肪酸水平上升（Ｐ＜０．０５）。停用鱼油两周后，其脑磷脂中脂肪酸水平与     

多不饱和脂肪酸对儿童早期发育的影响

母乳中含有丰富的多不饱和脂肪酸,n-3系和n-6系多不饱和脂肪酸具有重要的生物学意义,两者在儿童脑发育、视觉发育和免疫调节方面起着重要作用.胎儿可通过胎盘获得多不饱和脂肪酸,婴幼儿则可通过母乳获得,而无法提供母乳者可服用强化多不饱和脂肪酸配方奶.由于早产儿在孕期获得的多不饱和脂肪酸相对足月儿较少,故对其在出生后应及时补充多不饱和脂肪酸,以促进早产儿的脑发育和视觉发育,调节早产儿的免疫功能,降低疾病的发生率.该文主要介绍了多不饱和脂肪酸的生理作用、来源及在儿童早期发育方面的促进作用.     

食鱼与卒中

食鱼与卒中［英］／ＧｉｌｕｍＲＦ…∥ＡｒｃｈＩｎｔＭｅｄ．－１９９６，１５６（５）．－５３７～５４２有些流行病学研究发现食鱼与冠心病危险性降低有关。但对食鱼与卒中的关系知之甚少。由于鱼油中ｎ－３多不饱和脂肪酸的血小板抑制作用可能会增加出血性卒中和／或...     

鱼油对小鼠脑磷脂中脂肪酸组成的影响

昆明种小鼠随机分成两组，对照组和鱼油组，按小鼠处死时间，对照组分三个亚组，鱼油组分四个亚组。取小鼠脑组织，采用气相色谱法测其脑磷脂中脂肪酸组成，考察鱼油中ｎ一３系多不饱和脂肪酸对小鼠大脑的影响，结果表明：鱼油可使小鼠脑重增加（Ｐ＜０．０５），使脑磷脂中饱和脂肪酸，单不饱和脂肪酸和ｎ一６系多不饱和脂肪酸水平降低，使ｎ一３系多不饱和脂肪酸水平上升（Ｐ＜０．０５）。停用鱼油两周后，其脑磷脂中脂肪酸水平与对照组的水平接近，即鱼油对脑磷脂中脂肪酸组成的影响作用逐渐减弱。由此推论，在人脑早期形成发育过程中，适时、适量、持续补充人体必需ｎ一３系多不饱和脂肪酸是必要的。     

n-3系多不饱和脂肪酸与健康

n- 3系多不饱和脂肪酸具有防治心血管疾病、促进脑组织及视网膜的正常生长发育等生理作用 ,因此越来越引起人们摄取的兴趣。本文从目前的膳食结构以及 n- 3系多不饱和脂肪酸的生理作用阐述了摄取 n- 3系多不饱和脂肪酸的必要性 ,并对 n- 3系多不饱和脂肪酸的来源、摄取剂量、副作用以及需注意的问题等进行了探讨     

Omega-3多不饱和脂肪酸的研究进展

Omega3多不饱和脂肪酸(omega-3 polyunsat urated fatty acids.n-3PUFAs;叉称n-3,ω-3),是人体生长和健康所必需的物质,届于18-24碳脂肪酸家族,其碳链上具有3个以上的双键,依照第一个双键距离甲基端碳原子不同分为n-3系、n-6系、n-7系、n-9系(即n编号系统,也叫w编号系统),n-3PUFAs是指从脂肪酸碳链甲基端算起,第一个双键位于第3位碳原于上的多不饱和脂肪酸,属于亚麻酸类.     

多不饱和脂肪酸的研究概况

多不饱和脂肪酸具有广泛而重要的生物学功能，ｎ－３和ｎ－６多不饱和脂肪酸都是合成类廿碳烷酸化合物的前体，它们在体内的平衡对于稳定细胞膜功能，调控基因表达，维持细胞因子和脂蛋白平衡，抗心血管病，促进生长发育等方面起着重要作用，是目前营养生化研究热点之一。     

紫外线和尿刊酸对小鼠迟发性超敏反应的影响

采用改良的Ｒｏｓｓ 方法，不同时间点分别给小鼠腹腔注射尿刊酸和皮下注射半抗原，测量耳厚作为指标。观察不同剂量的顺式尿刊酸对小鼠迟发性超敏反应的抑制作用，并与紫外线引起的免疫抑制作用相比较。结果显示注射顺式尿刊酸２００μｇ 、４００μｇ 和６００μｇ 组的免疫抑制率分别是４７－３ ％ 、５２－５ ％ 和５６－０ ％ ，呈现剂量反应关系。一次照射紫外线５－０ｋＪ／ｍ ２ 组的免疫抑制率是４３－６ ％ 。紫外线引起皮肤免疫功能抑制的途径之一是把皮肤组织中的尿刊酸从反式结构转变成顺式结构。     

外源性脂肪酸对结肠癌细胞生长的影响及其可能机制

目的：探讨八种外源性脂肪酸对人结肠癌细胞生长的影响及其作用机制。方法：体外实验中应用MTT法观察外源性脂肪酸对细胞生长的影响，并对细胞脂质过氧化反应产物丙二醛含量进行了测定。结果：多不饱和脂肪酸可抑制结肠癌细胞生长，饱和及单不饱和脂肪酸作用不明显，八种脂肪酸对正常成纤维细胞没有明显抑制作用。多不饱和脂肪酸可引起细胞内丙二醛含量升高。结论：多不饱和脂肪酸可选择性抑制肿瘤细胞生长，脂质过氧化反应增强，可能是其主要作用机制。     

Dietary fatty acid modulation of mucosally-induced tolerogenic immune responses

Immunological unresponsiveness or hyporesponsiveness (tolerance) can be induced by feeding protein antigens to naive animals. Using a classical oral ovalbumin gut-induced tolerance protocol in BALB/c mice we investigated the effects of dietary n-6 and n-3 polyunsaturated fatty acids (PUFA) on high-and low-dose oral tolerance (and in non-tolerised animals, i.e. effects of antigen challenge alone) in relation to lymphoproliferative, cytokine and antibody responses. Fish oil rich in long-chain n-3 fatty acids decreased both T-helper (Th) 1- and Th2-like responses. In contrast, borage (Borago officinalis) oil rich in n-6 PUFA, of which gamma-linolenic acid is rapidly metabolised to longer-chain n-6 PUFA, increased Thl-like responses and decreased Th2-like responses, and possibly enhanced suppressor cell or Th3-like activity. These findings are in general agreement with other studies on the effects of long chain n-3 PUFA on immune system functions, and characterise important differences between long-chain n-3 and n-6 PUFA, defining more precisely and broadly the immunological regulatory mechanisms involved. They are also discussed in relation to autoimmune disease.     

代谢综合征患者血清三酰甘油多不饱和脂肪酸谱与内脏脂肪的关系

目的 探讨血清三酰甘油中的n-6与n-3必需多不饱和脂肪酸（PUFA）各组分及其比例与代谢综合征患者核磁共振测量的腹腔内脏脂肪面积（MRI-IAF）的关系.方法 比较在体检中新发现的代谢综合征和健康人群的代谢和体脂指标的差异,探讨代谢综合征患者血清三酰甘油脂肪酸谱各组分与MRI-IAF等体脂参数的相关性,并且以相关的血清脂肪酸谱组分为被筛选变量,逐步回归分析以上变量对MRI-IAF、腰围和体质指数（BMI）的影响.结果 代谢综合征组的各项体脂及代谢指标均较对照组差,其中MRI-IAF差距较大[（108.3±13.3）cm2 vs.（63.0±7.1）cm2,t=18.28,P＜0.05）],代谢综合征组血清三酰甘油的n-6/n-3 PUFA比值高于对照组（10.1±3.3vs.7.2±2.1,t=8.564,P＜0.05）,而C18∶3 n-3[（1.4±0.4）％vs.（1.7±0.6）％,t=-3.295]、C20∶5 n-3[（0.2±0.2）％vs.（0.6±0.6）％,t=-3.611]、C22∶6n-3[（0.9±0.5）％vs.（1.2±0.6）％,t=-2.920]及n-3PUFA低于对照组[（2.5±0.6）％vs.（3.7±1.2）％,t=-7.034]（P均＜0.05）,所有n-6 PUFA及C22∶5 n-3的差异无统计学意义;n-6/n-3 PUFA、n-3 PUFA、二十二碳六烯酸和二十碳五烯酸均与MRI-IAF （r=-0.377～0.565,P=0.024）相关,n-6/n-3 PUFA还与腰围（r=0.400,P=0.016）和BMI相关（r=0.357,P=0.033）,而n-6 PUFA与各体脂参数不相关;逐步回归分析提示n-6/n-3PUFA比值与MRI-IAF、腰围、BMI的相关性较强（校正的R2=0.102～0.299,P=0.033）.结论 血清三酰甘油n-6/n-3 PUFA比值和n-3 PUFA与代谢综合征患者MRI-IAF等体脂参数相关,补充膳食n-3 PUFA的同时可能还需要考虑避免n-6 PUFA的过量摄入.     

Protective effect of dietary n-3 polyunsaturated fatty acids on myocardial resistance to ischemia-reperfusion injury in rats

Dietary n-3 polyunsaturated fatty acids (PUFA) reduce coronary heart disease (CHD) complications, such as chronic arrhythmia and sudden cardiac death. Improved myocardial resistance to ischemia-reperfusion injury results in smaller myocardial infarction, which is a major factor in the occurrence of CHD complications. We hypothesized that a specific dietary fatty acid profile (low in saturated and n-6 PUFA but high in plant and marine n-3 PUFA) may improve myocardial resistance to ischemia-reperfusion injury and reduce infarct size. To test this assumption, we used a well-defined rat model of myocardial infarction. Based on our results, in comparison to a diet that is high in either saturated or n-6 PUFA but poor in plant and marine n-3 PUFA, a diet that is low in saturated fats and n-6 PUFA but rich in plant and marine n-3 PUFA results in smaller myocardial infarct size (P < .01). The effects of the 3 diets were also examined by analyzing the fatty acid composition of plasma, erythrocyte cell membranes, and the phospholipids of myocardial mitochondria. The results show a great accumulation of n-3 PUFA and a parallel decrease in arachidonic acid, the main n-6 PUFA, in plasma, cell membranes, and cardiac mitochondria (P < .0001). We conclude that improved myocardial resistance to ischemia-reperfusion may be one of the critical factors explaining the protective effects of dietary n-3 PUFA against CHD complications in humans. In addition to increasing n-3 PUFA intake, an optimal dietary pattern aimed at reducing cardiovascular mortality should include a reduction of the intake of both saturated and n-6 PUFA.     

Seasonal Variations in Fatty Acid Composition and the N-6/N-3 Fatty Acid Ratio of Pikeperch (Sander LUCIOPERCA) Muscle Lipids

Total lipid, fatty acid composition and the N-6/N-3 fatty acid ratios of muscle of pikeperch (Sander lucioperca) was determined once every two months. The ratio of unsaturated fatty acids (UFA) was higher than half of the total fatty acid content, and the monounsaturated fatty acid (MUFA) was higher than the polyunsaturated fatty acid (PUFA) ratio. The n-3 fatty acids were present in excess of the n-6 fatty acids. Eicosapentaenoic (EPA), docosahexaenoic (DHA), and arachidonic (AA) acids were the most abundant PUFA. The fatty acid composition and n-6/n-3 fatty acids ratio in the muscle of pikeperch are significantly influenced by spawning and the season. Relative proportions of PUFA (especially n-3 fatty acids) diminished significantly with the maturation of gonads. The ratio of n-6/n-3 fatty acids was less than one except during the reproduction period. This result suggests that meat quality of pikeperch is very good except during the spawning period with respect to the n-6/n-3 fatty acids ratio.     

Increasing the dietary (n-3) to (n-6) polyunsaturated fatty acid ratio increases tumor necrosis factor production by murine resident peritoneal macrophages without an effect on elicited peritoneal macrophages.

Tumor necrosis factor (TNF), prostaglandin (PG) E2 and 6-keto-PGF1 alpha production by murine peritoneal macrophages was monitored following in vitro stimulation with lipopolysaccharide. Macrophages were obtained from mice fed diets containing increasing ratios of (n-3) to (n-6) fatty acids by addition of (n-3) polyunsaturated fatty acids (PUFA) to the (n-6) fatty acids in the diet, or by substituting (n-3) PUFA for the (n-6) fatty acids in the diet. Increasing the dietary (n-3) to (n-6) fatty acid ratio from 0 to 1 increased both cell-associated and secreted TNF production by resident peritoneal macrophages but did not affect TNF production by macrophages elicited with Complete Freund's Adjuvant (CFA). With increasing dietary (n-3): (n-6) ratio there was a decrease in the prostaglandin production by resident peritoneal macrophages, which may partly explain the increased TNF production. The CFA-elicited macrophages produced less prostaglandin than the resident macrophages, and the lower prostaglandin production may partly explain the lack of effect of dietary (n-3) PUFA on TNF production by CFA-elicited macrophages. Increasing the TNF production by resident macrophages with dietary (n-3) PUFA may be beneficial in enhancing antitumor actions and antipathogenicity; by not increasing the high TNF production of inflammatory macrophages, (n-3) PUFA may protect against undesirable systemic inflammatory effects of overproduction.     

n-6 fatty acid-specific and mixed polyunsaturate dietary interventions have different effects on CHD risk: a meta-analysis of randomised controlled trials

Randomised controlled trials (RCT) of mixed n-6 and n-3 PUFA diets, and meta-analyses of their CHD outcomes, have been considered decisive evidence in specifically advising consumption of 'at least 5-10 % of energy as n-6 PUFA'. Here we (1) performed an extensive literature search and extracted detailed dietary and outcome data enabling a critical examination of all RCT that increased PUFA and reported relevant CHD outcomes; (2) determined if dietary interventions increased n-6 PUFA with specificity, or increased both n-3 and n-6 PUFA (i.e. mixed n-3/n-6 PUFA diets); (3) compared mixed n-3/n-6 PUFA to n-6 specific PUFA diets on relevant CHD outcomes in meta-analyses; (4) evaluated the potential confounding role of trans-fatty acids (TFA). n-3 PUFA intakes were increased substantially in four of eight datasets, and the n-6 PUFA linoleic acid was raised with specificity in four datasets. n-3 and n-6 PUFA replaced a combination of TFA and SFA in all eight datasets. For non-fatal myocardial infarction (MI)+CHD death, the pooled risk reduction for mixed n-3/n-6 PUFA diets was 22 % (risk ratio (RR) 0.78; 95 % CI 0.65, 0.93) compared to an increased risk of 13 % for n-6 specific PUFA diets (RR 1.13; 95 % CI 0.84, 1.53). Risk of non-fatal MI+CHD death was significantly higher in n-6 specific PUFA diets compared to mixed n-3/n-6 PUFA diets (P = 0.02). RCT that substituted n-6 PUFA for TFA and SFA without simultaneously increasing n-3 PUFA produced an increase in risk of death that approached statistical significance (RR 1.16; 95 % CI 0.95, 1.42). Advice to specifically increase n-6 PUFA intake, based on mixed n-3/n-6 RCT data, is unlikely to provide the intended benefits, and may actually increase the risks of CHD and death.     

A high ratio of dietary n-6/n-3 polyunsaturated fatty acids is associated with increased risk of prostate cancer

Experimental studies suggest omega-3 (n-3) polyunsaturated fatty acids (PUFA) suppress and n-6 PUFA promote prostate tumor carcinogenesis. Epidemiologic evidence remains inconclusive. The objectives of this study were to examine the association between n-3 and n-6 PUFA and prostate cancer risk and determine if these associations differ by race or disease aggressiveness. We hypothesize that high intakes of n-3 and n-6 PUFA will be associated with lower and higher prostate cancer risk, respectively. A case-control study comprising 79 prostate cancer cases and 187 controls was conducted at the Durham VA Medical Center. Diet was assessed using a food frequency questionnaire. Logistic regression analyses were used to obtain odds ratios (ORs) and 95% confidence intervals (95% CI) for the associations between n-3 and n-6 PUFA intakes, the dietary ratio of n-6/n-3 fatty acids, and prostate cancer risk. Our results showed no significant associations between specific n-3 or n-6 PUFA intakes and prostate cancer risk. The highest dietary ratio of n-6/n-3 was significantly associated with elevated risk of high-grade (OR, 3.55; 95% CI, 1.18-10.69; P_trend = 0.03), but not low-grade prostate cancer (OR, 0.95; 95% CI, 0.43-2.17). In race-specific analyses, an increasing dietary ratio of n-6/n-3 fatty acids correlated with higher prostate cancer risk among white men (P_trend = 0.05), but not black men. In conclusion, our findings suggest that a high dietary ratio of n-6/n-3 fatty acids may increase the risk of overall prostate cancer among white men and possibly increase the risk of high-grade prostate cancer among all men.     

(n-3) Polyunsaturated fatty acids promote activation-induced cell death in murine T lymphocytes

Previous studies showing dietary (n-3) polyunsaturated fatty acids (PUFA) attenuate T cell immune-mediated inflammatory diseases led us to hypothesize that (n-3) PUFA promote activation-induced cell death (AICD) in T cells. Because T cell subsets display a differential resistance to AICD, we compared the effects of (n-3) PUFA feeding on T cells stimulated in vitro to express different cytokine profiles. Mice were fed either diets lacking (n-3) PUFA (control) or (n-3) PUFA-containing diets for 14 d. Splenic T cells were stimulated with alphaCD3/alphaCD28, phorbol myristate acetate (PMA)/Ionomycin or alphaCD3/PMA for 48 h, followed by reactivation with the same stimuli for 5 h. Apoptosis was measured using Annexin V/propidium iodide. (n-3) PUFA were selectively incorporated into membrane phospholipid pools. Cytokine analyses revealed that (n-3) PUFA enhanced AICD only in T cells expressing a T helper cell (Th)1-like cytokine profile after stimulation with PMA/Ionomycin compared to mice fed the (n-6) PUFA control diet (P = 0.0008). In contrast, no increase in apoptosis was seen in T cells stimulated with alphaCD3/PMA, which exhibited a Th2 cytokine profile. These data demonstrate that the ability of (n-3) PUFA to promote AICD is dependent on the activation stimulus. In conclusion, we have identified a novel mechanism by which (n-3) PUFA modulate T cell-mediated immunity by selective deletion of Th1-like cells while maintaining or enhancing the Th2-mediated humoral immune response.     

Fatty acid composition of the red blood cell membrane in relation to menopausal status

PURPOSE: Menopausal status effects female anatomical functioning at a variety of system-wide and cellular levels, including cellular membrane composition. This study analyzed a nested case-control ORDET data set of 433 pre and post-menopausal breast cancer controls to examine the effects of menopausal status on the fatty acid composition of the red blood cell membrane.METHODS: ORDET is a prospective cohort study conducted in Italy to investigate the etiologic role of hormones and diet in breast cancer development. The fatty acid composition was measured and analyzed by gas chromotography, comparing retention time with standard measurement. Twenty-two individual fatty acids were measured, recorded, and categorized into four fatty acid groups: saturated, monounsaturated, polyunsaturated n-6 (PUFA n-6), and polyunsaturated (PUFA n-3) fatty acids.RESULTS: Post-menopausal women had consistently lower mean values for all four fatty acid categories and all individual fatty acids. Statistically significant mean differences, by menopausal status, were observed for three of the four fatty acid categories: saturated fatty acids (p = 0.006), PUFA n-6 acids (p = 0.001), and PUFA n-3 acids (p = 0.000). The biggest statistically significant differences in mean values among individual fatty acids for each category were observed for Palmitic acid (p = 0.009), Oleic acid (p = 0.040), Linoleic acid (p = 0.000), and Docosahexaenoic acid (p = 0.000). Individual fatty acids were also less highly correlated among post-menopausal women.CONCLUSIONS: There was an observed relationship between menopausal status and the fatty acid composition of the red blood cell membrane that warrants further study. This relationship may contribute to the physiological and psychological changes that occur during and after menopause, and may have far-reaching implications for women's health.