单不饱和脂肪酸膳食通过缓解氧化应激改善糖耐量正常人群的胰岛素敏感性

20例健康受试者分别接受单不饱和脂肪酸饮食、多不饱和脂肪酸饮食、饱和脂肪酸饮食3d,单不饱和脂肪酸可以改善机体的氧化应激状态,从而改善胰岛素敏感性.     

A diet rich in monounsaturated fatty acids improves the lipid profile of mice previously on a diet rich in saturated fatty acids

This study investigated whether switching from a diet rich in saturated fatty acids (SAFAs) to a diet rich in monounsaturated fatty acids (MUFAs) or to one with equal amounts of MUFAs-SAFAs favorably affects the lipid profile of hypercholesterolemic mice. C57BL/6 mice (n = 82) were allocated into 4 groups. The first group (control, n = 10) was fed standard chow. The 3 remaining groups (n = 24 mice/group) were fed a SAFA-rich diet for 8 weeks and were then allocated for 16 weeks to either a MUFA-rich diet, an equal in MUFAs-SAFAs-rich diet, or continued the previous SAFA-rich diet. After 8 weeks, mice consuming SAFA-rich diet had increased weight, total cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C) levels (P < .05 vs baseline). At week 24, MUFA-rich and MUFA-SAFA rich diets decreased TC and low-density lipoprotein cholesterol (LDL-C) levels (P < .05) compared with week 8. In conclusion, switching to MUFA-rich diets or substituting half of the SAFAs with MUFAs can reverse diet-induced-hypercholesterolemia.     

The effect of abdominal obesity on insulin sensitivity and serum lipid and cytokine concentrations in African women

OBJECTIVES: Studies have shown clear associations of abdominal obesity with lipid and glucose metabolism and cytokine levels in a number of different population groups. However, no such studies have been performed in an African population in which visceral adipose tissue levels have been shown to be lower than in European subjects. DESIGN AND PATIENTS: Cross-sectional analysis in 124 African women. MEASUREMENTS: Fasting serum samples were taken from all subjects and anthropometric measurements obtained. Blood levels of glucose, insulin, total cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, triglyceride, interleukin (IL)-6, IL-8 and IL-18 were measured. Subjects were separated into normal and abnormal glucose tolerant groups and into tertiles according to waist circumference (WC). Insulin resistance was assessed using the homeostasis model assessment (HOMA). RESULTS: Abnormal glucose-tolerant subjects had higher WC, glucose and HOMA levels than the normal glucose-tolerant group. Increased WC was associated with higher triglyceride, insulin and HOMA levels and lower HDL levels. Multiple regression analyses showed that WC associated positively with HOMA and serum triglyceride levels and negatively with HDL levels. IL18 was a positive but weak determinant of the HOMA level and BMI correlated positively with serum IL-6 concentrations. CONCLUSIONS: Although previous studies have shown that African subjects have a lower visceral adipose depot size than European subjects, abdominal obesity is still associated with insulin resistance and dyslipidaemia. The association between abdominal obesity and metabolic dysfunction within this population is not dependent upon IL-6, IL-8 or IL-18.     

Effects of free fatty acids on insulin secretion in obesity

The prevalence of obesity in Western society has reached epidemic proportions and its aetiological role in the development of type 2 diabetes has made finding an effective treatment for the condition of crucial importance. Of the many consequences of obesity, derangements in glucose metabolism present one of the greatest problems to health. While the role of obesity in causing insulin resistance has received much attention, the effect of obesity on β‐cell failure and the consequent development of type 2 diabetes requires re‐emphasis. In this review, the current understanding of the effects of elevated free‐fatty acids on β‐cell function will be examined, including a discussion of potential mechanisms. In particular, dysregulation of biochemical pathways and alterations in key enzymes, proteins and hormones will be considered as grounds for the progression to a diabetic phenotype.     

替米沙坦对高脂饮食大鼠肥胖和血脂水平的影响

目的 探讨运用替米沙坦阻断肾索-血管紧张素系统(RAS)对大鼠肥胖和血脂水平的影响.方法 40只雄性SD大鼠随机分为对照组、对照治疗组、高脂组、高脂治疗组,分别用正常饮食、正常饮食联合替米沙坦、高脂饮食、高脂饮食联合替米沙坦处理.各组大鼠体质量每周测量一次,喂养10周后取大鼠静脉血检测血脂,测量内脏脂肪质量,计算Lee's指数.结果 高脂饮食组大鼠平均体质鼍随时间变化的趋势显著高于对照组和高脂治疗组(P=0.046,P=0.035).高脂治疗组大鼠平均体质量的增加和平均内脏脂肪质量均显著低于高脂组(P=0.012,P=0.024).高脂治疗组大鼠平均甘油三酯(TG)水平显著低于高脂组(P=0.002),但平均高密度脂蛋白胆固醇(HDL-c)水平显著高于高脂组(P=0.023).结论 替米沙坦可以抑制大鼠高脂饮食引起的肥胖,同时改善高脂饮食引起的血脂紊乱.     

Relationship between insulin sensitivity and degree of obesity in mild hypertension.

Eighteen patients with mild hypertension (diastolic blood pressure > or = 90 and < 104 mm Hg) and 15 normotensive control subjects were studied. Insulin tolerance tests (ITT) and fasting plasma insulin (FPI) level measurements were performed to evaluate insulin sensitivity. Insulin sensitivity, as measured with the ITT, showed a strong correlation with body mass index (BMI) in the hypertensive and control groups (r = -0.68, p < 0.01 and r = -0.61, p < 0.01, respectively). The fasting insulin levels also correlated significantly with BMI in both groups (r = 0.55, p < 0.05 in the hypertensive and r = 0.76, p < 0.01 in the control group). Insulin sensitivity in the hypertensive subjects whose BMI was < or = 27.0 kg/m2 (nonobese), as measured with the ITT and FPI, was not different from the nonobese normal controls (K(itt), 5.36 +/- 1.74% min-1 versus 5.61 +/- 1.66% min-1, respectively, p > 0.2; FPI, 5.8 +/- 3.4 microU/ml versus 7.1 +/- 2.5 microU/ml, respectively, p > 0.2). Also, insulin sensitivity, as measured with the ITT, was not statistically significantly different between hypertensive and normotensive obese subjects (K(itt), 2.82 +/- 1.55% versus 3.90 +/- 0.67% min-1, respectively, p > 0.1). When fasting plasma insulin levels were compared, a higher level was observed in the obese normotensive subjects than in the obese hypertensive group (FPI, 19.8 +/- 10.0 microU/ml and 11.5 +/- 4.9 microU/ml, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

老问题新认识:对脂肪酸与肥胖和胰岛素抵抗关系的再评价

美国牛津糖尿病中心的Karpe F等近期发表的"Fatty acids,obesity,and insulin resistance:time for a reevaluation"(Diabetes,2011,60:2441)。根据他们自己的研究和文献对脂肪酸(FA)在肥胖和IR中的关系撰文提出新认识。首先,非酯化脂肪酸(NEFA)的基本功能现在认为NEFA是将储存在脂肪组织的TG转运到其利用处的转运工具,而不只是供肝、心肌等利用。第二,上身和腹部皮下脂肪堆积是NEFA主要来源,不同于普遍认为只有一小部分NEFA来自腹内脂肪组织。第三,空腹血浆NEFA几乎全部来自脂肪细胞内TG水解,但餐后血浆NEFA约40%～50%来自食物脂肪乳糜颗粒中的TG被LPL水解,脂肪利用被胰岛素抑制,在富含碳水化合物餐后NEFA浓度下降。第四,NEFA升高伴急性IR,常见于肥胖,控制不良的糖尿病患者,IR伴异位脂肪——脂肪组织以外的胰岛素效应组织如骨骼肌细胞脂质增加(细胞TG),反映脂肪清除损害甚于摄取。现撷其精要摘译并如以评论,供广大读作者参考。     

Adipose tissue fatty acids and insulin sensitivity in elderly men

Aims/hypothesis  

Dietary fatty acids may affect insulin sensitivity. Adipose tissue fatty acid composition partly reflects long-term dietary intake, but data from large studies regarding relationships with insulin sensitivity are lacking. We aimed to determine the association between adipose tissue fatty acids and insulin sensitivity in elderly Swedish men.     

Relationship among obesity,blood lipids and insulin resistance in Bangladeshi adults

IntroductionInsulin resistance (IR) and abnormal lipid profiles are the risk factors for cardiovascular diseases in obesity. To clarify the relationship of the changes in insulin resistance, body weight and lipid profile, the present study was performed on Bangladeshi adults, total of 1500 individuals at the time of their general health examination in the hospital.MethodsAfter exclusion of other endocrine diseases, the remaining 772 patients were classified as IR ≥ 2 and IR < 2 based on the homeostatic model assessment-estimated insulin resistance (HOMA-IR) index. The endocrine disease free subjects were further clustered based on age, gender and obesity. The anthropometric and biochemical profiles were statistically analyzed and correlated with IR ≥ 2 and IR<2 groups as well as other clusters of the subjects. Apart from some disparities, notable differences were observed in all anthropometric data.ResultsTotal cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL) and serum insulin levels were significantly higher in IR ≥ 2 group in comparison with IR<2 group. Obesity and dyslipidemia were associated as prevalent components of IR. Generalized linear model revealed that TC: LDL and TG: HDL had significant effect on IR. Age group II (41–60 years old) subjects had significantly higher lipid profile compared to age group I (20–40 years old) and age group III (61–80 years old).ConclusionsResults reported herein support the notion that lipoprotein ratios might be the reliable biomarkers to evaluate IR.     

Effects of lipid-lowering diets enriched with monounsaturated and polyunsaturated fatty acids on serum lipoprotein composition in patients with hyperlipoproteinaemia.

Controlled comparisons of the effects of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) as a part of lipid-lowering diets in persons with hyperlipoproteinaemia are sparse. The present study was carried out at a metabolic ward. Forty hyperlipidaemic patients (25 hypercholesterolaemic and 15 hypertriglyceridaemic) were given a 3-week diet rich in either MUFA (saturated fatty acids 7.3 energy% (E%), MUFA 14.6 E%, PUFA 4.8 E%) or PUFA (saturated fatty acids 7.8 E%, MUFA 8.4 E%, PUFA 10.4 E%), but otherwise with an identical composition. The mean serum cholesterol reduction on the MUFA diet was 12% (P < 0.001), with a low density lipoprotein cholesterol reduction of 11% (P < 0.001). The corresponding reductions on the PUFA diet were 15% (P < 0.001) and 16% (P < 0.001). The serum apolipoprotein B and A-I concentrations decreased highly significantly by 13% and 11% on the MUFA diet and by 14% and 11% on the PUFA diet. None of these changes differed between the two diets. Neither were there any differences between the diets regarding the effects on blood glucose, serum insulin and plasma fibrinogen, but there was a significant decrease in serum insulin with a significant reduction of the insulin/glucose ratio after the MUFA diet. The results of this study indicate that MUFA and PUFA are interchangeable within the given frames in lipid lowering diets even in patients with hyperlipidaemia.     

Comparison of a high saturated fat diet with a high carbohydrate diet during pregnancy and lactation: effects on insulin sensitivity in offspring of rats

Insulin resistance plays a critical role in metabolic syndrome and is influenced by the amount and saturation of dietary fat. Both prenatal over and under nutrition can program susceptibility to insulin resistance. The aim of the study was to explore the impact of dietary fat given to mothers during gestation on the insulin sensitivity of the offspring. Female Wistar rats were fed with diets rich in carbohydrate (CHO) or saturated fat (SAFA) during pregnancy. The male offspring was split into 5 subgroups: groups 1 (control) and 3 continued on CHO or SAFA after birth, respectively. Group 2 with mothers on CHO continued on the CHO diet during the nursing period and changed to SAFA postweaning. Group 4 with mothers on SAFA continued on SAFA during the weaning period and changed to CHO postweaning. For group 5 the offspring of mothers given SAFA diet was changed to nursing mothers on CHO diet immediately after birth and continued on the same diet postweaning. At the age of 16 weeks, a euglycemic hyperinsulinemic clamp was performed. The glucose infusion rate was lowered in the groups receiving the SAFA diet (group 2, 24.7 +/- 2.0 mg/kg per minute; group 3, 22.0 +/- 1.9 mg/kg per minute; P < .05) compared with group 1 (32.2 +/- 2.3 mg/kg per minute). We did not detect any alterations in the rate of glucose disappearance during the clamp for any of the groups compared with group 1. A diet high in SAFA given to mothers during gestation and/or the weaning period does not seem to have deleterious effects on the insulin sensitivity in the offspring.     

血清irisin水平与腹型肥胖成人体脂率相关

目的探索血清irisin水平与体脂率的关系。方法选取2011年4月至2012年8月入组的厦门莲前社区腹型肥胖（男性腰围≥90cm,女性≥85cm）居民1204名,所有受试者接受问卷调查、体格测量、生化指标及血清irisin的测定,采用生物电阻抗的方法测定体脂率。数据运用t检验、单因素方差分析及logistic回归等进行统计分析。结果1204名肥胖受试者中女性807例,男性397例,年龄（534-7）岁（35～65岁）。女性体脂率高于男性[（39±4）％比（26±4）％,t=-53．50,P〈0．05],女性血清irisin水平亦高于男性[8．9（4．7—17．2）比7．6（4．0～14．4）肛∥L,t=-2．87,P〈0．05]。按血清irisin水平对受试者进行三分位分层分析,发现不同的血清irisin组间体脂率、总胆固醇（TC）、低密度脂蛋白胆固醇（LDL—C）差异有统计学意义（F=4．49、3．63、4．88,趋势P均〈0．05）。对体脂率进行分层分析,发现随着体脂率的增加,血清irisin水平增加（F=3．33,P〈0．05）,进一步进行logistic回归分析发现,校正年龄、性别、体质指数（BMI）、腰围、体力活动、血压、吸烟饮酒、TG、TC、LDL—C、高密度脂蛋白胆固醇（HDL—C）、糖化血红蛋白（HbAlC）、空腹血糖（FPG）、稳态模型胰岛素抵抗指数（HOMA—IR）后,体脂率每升高一个百分比,血清irisin水平则增加13％（OR=1．13,95％CI：1．01～1．25,X^2=4．83,P〈0．05）。结论在腹型肥胖人群中血清irisin水平与体脂率有关。     

Effect of a high glucose diet on insulin binding and insulin action in rat adipocytes

Summary To elucidate the mechanisms whereby changes in dietary composition affect the action of insulin on glucose metabolism, insulin binding and glucose uptake and oxidation have been studied in epididymal fat pad adipocytes from rats fed high glucose diets for 5 and 10 days. After 5 days, insulin binding was increased, due mainly to an increased number of receptors (3.4×10⁵ vs. 2.4×10⁵ sites per cell) in spite of increased plasma insulin levels (3.0±0.2 vs. 2.1±0.1 g/l; p<0.05). The maximal response of glucose oxidation to insulin was increased (925±55 vs. 510±58 n moles/2×10⁵ cells/2h; p<0.01) and the dose-response curve of glucose uptake was shifted to the left. After 10 days, receptor number decreased to the control level and the effect of insulin on glucose uptake and oxidation (% basal) were similar to controls. Thus, in the early stage of high glucose feeding, insulin receptor number, insulin sensitivity of glucose uptake, and insulin responsiveness of glucose oxidation were increased.     

Effects of monounsaturated fatty acids v complex carbohydrates on serum lipoproteins and apoproteins in healthy men and women

The effects of a high-carbohydrate, high-fiber diet and an olive-oil-rich diet on the distribution of cholesterol over the various lipoproteins, on serum apolipoproteins, and on the composition of HDL2 and HDL3 were studied under strict dietary control. Forty-eight healthy subjects first consumed a high-saturated-fat diet [proportion of energy, en%] (saturated fat 20 en%, total fat 38 en%) for 17 days. For the next 36 days, 24 subjects consumed a diet high in complex carbohydrates (monounsaturated fat 9 en%, total fat 22 en%) and the other 24 consumed a high-fat, olive-oil-rich diet (monounsaturated fat 24 en%, total fat 41 en%). The amounts of protein (12% to 14 en%), polyunsaturated fat (4 to 5 en%), and cholesterol (31 to 35 mg/MJ) were similar in all three diets. Serum cholesterol levels fell by 0.44 mmol/L in subjects consuming the carbohydrate diet and by 0.52 mmol/L for those receiving the olive-oil-rich diet. VLDL-cholesterol levels rose by 0.08 mmol/L in the carbohydrate group and fell by 0.08 mmol/L in the olive oil group (P less than .05 for difference between test diets). HDL2 and LDL cholesterol levels fell to the same extent on both diets. HDL3 cholesterol fell by 0.09 mmol/L on the high-carbohydrate diet and increased by 0.01 mmol/L on the olive oil diet (P less than .05). There was no change in the composition of HDL3, suggesting that the fall was due to a decrease in the total number of circulating particles.(ABSTRACT TRUNCATED AT 250 WORDS)     

替米沙坦对肥胖性高血压患者体脂、血脂及胰岛素抵抗的影响

目的探讨替米沙坦对肥胖性高血压患者体脂、血脂、胰岛素抵抗的影响。方法 BMI≥25 kg/m2的原发性高血压患者60例,随机分成观察组和对照组,并分别给予替米沙坦和硝苯地平缓释片干预,观察干预前后BP、BMI、腰臀比（W/H）、TC、LDL-C、TG、胰岛素抵抗指数（IRI）、高敏C反应蛋白（hsCRP）等指标变化。结果与干预前比较,干预后12、24周两组BP均下降（P〈0.01）,干预后24周观察组W/H、TGI、RI、hsCRP下降（P〈0.01或P〈0.05）。观察组IRI、hsCRP的变化与SBP、DBP、BMI、W/H、TG等呈直线相关。结论替米沙坦除良好的降压外,有一定的减轻腹型肥胖、控制TG和改善胰岛素抵抗的作用。     

Inborn errors of metabolism with a protein-restricted diet: Effect on polyunsaturated fatty acids

Previous studies have shown that phenylketonuric patients display a deficiency in long-chain polyunsaturated fatty acids. A study has now been performed on 13 cases (5 with methylmalonic acidaemia and 8 with urea cycle disorders) whose dietary treatment also implies a limitation in protein-rich food. Plasma and red-cell phospholipid fatty acid profiles were studied. The most relevant results were a lower percentage of docosahexaenoic acid in plasma and red-cell phospholipids (0.91% ± 0.53% vs 2.88% ± 1.17% and 2.07% ± 0.92% vs 3.62% ± 1.01% (p < 0.001)) and a lower percentage of arachidonic acid in plasma (5.22% ± 2.02% vs 8.3% ± 2.11% (p < 0.001)).A long-chain polyunsaturated acid deficiency has also been confirmed in this group of metabolic patients and a dietary supplement is recommended since this population is subject to a special risk factor with regard to adequate psychomotor development. By extrapolating these data to the general population, the possibility can be inferred that long-chain polyunsaturated fatty acids are semi-essential in infant nutrition far beyond the breast-feeding period.