Effect of dietary fatty acid composition on substrate utilization and body weight maintenance in humans

Background/purpose

Dietary fat content is a primary factor associated with the increase in global obesity rates. There is a delay in achieving fat balance following exposure to a high-fat (HF) diet (≥ 40 % of total energy from fat) and fat balance is closely linked to energy balance. Exercise has been shown to improve this rate of adaptation to a HF diet. Recently, however, the role of dietary fatty acid composition on energy and macronutrient balance has come into question.

Methods

We chose studies that compared monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and saturated fatty acids (SFA). We have reviewed studies that measured diet-induced thermogenesis (DIT), energy expenditure (EE), or fat oxidation (FOx) in response to a HF meal challenge, or long-term dietary intervention comparing these fatty acids.

Results

While single-meal studies show that SFA induce lower DIT and FOx compared to unsaturated fats, the effect of the degree of unsaturation (MUFA vs. PUFA) appears to yet be determined. Long-term dietary interventions also support the notion that unsaturated fats induce greater EE, DIT, and/or FOx versus SFA and that a high MUFA diet induces more weight loss compared to a high SFA diet. Sex and BMI status also affect the metabolic responses to different fatty acids; however, more research in these areas is warranted.

Conclusion

SFA are likely more obesigenic than MUFA, and PUFA. The unsaturated fats appear to be more metabolically beneficial, specifically MUFA ≥ PUFA > SFA, as evidenced by the higher DIT and FOx following HF meals or diets.     

Increasing trends in dietary total fat and fatty acid intake among Korean children: using the 2007–2017 national data

BACKGROUND/OBJECTIVESThe prevalence of obesity has been increasing in Korean children. As an unhealthy diet is known as one of the major determinants of childhood obesity, assessing and monitoring dietary fat intake of children is needed.SUBJECTS/METHODSThis analysis included 9,998 children aged 3–11 yrs from the 2007–2017 Korea National Health and Nutrition Examination Surveys. Dietary data were obtained from a single 24-h dietary recall. Intakes of total fat and fatty acids, including saturated fatty acid (SFA), monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), n-3 fatty acid (n-3 FA), and n-6 fatty acid (n-6 FA) were evaluated as the absolute amount (g) and proportion of energy from each fatty acid (% of energy). The total fat and SFA intake were also assessed according to compliance with dietary guidelines. Linear trends in the dietary fats intake across the survey period were tested using multiple regression models.RESULTSTotal fat intake significantly increased from 38.5 g (20.3% of energy) to 43.4 g (23.3% of energy) from 2007 to 2017. This increase was mainly accounted for the increases in intakes of SFA (7.2% to 8.4% of energy) and MUFA (6.2% to 7.5% of energy). PUFA intake increased from 4.4 to 4.7% of energy during the 11-yrs period: from 0.57 to 0.63% of energy for n-3 FA and from 3.8 to 4.1% of energy for n-6 FA. The proportions of children who consumed amounts exceeding the dietary guidelines for total fat and SFA significantly increased from 2007 to 2017, with increases from 9.8% to 17.4% for total fat and from 36.9% to 50.9% for SFA.CONCLUSIONSProminent increasing trends in the consumption of total fat and SFA but tiny change in n-3 FA intake were observed in Korean children. The healthy intake of dietary fats should be emphasized in this population.     

High-Intensity Interval Training and α-Linolenic Acid Supplementation Improve DHA Conversion and Increase the Abundance of Gut Mucosa-Associated Oscillospira Bacteria

Obesity, a major public health problem, is the consequence of an excess of body fat and biological alterations in the adipose tissue. Our aim was to determine whether high-intensity interval training (HIIT) and/or α-linolenic acid supplementation (to equilibrate the n-6/n-3 polyunsaturated fatty acids (PUFA) ratio) might prevent obesity disorders, particularly by modulating the mucosa-associated microbiota. Wistar rats received a low fat diet (LFD; control) or high fat diet (HFD) for 16 weeks to induce obesity. Then, animals in the HFD group were divided in four groups: HFD (control), HFD + linseed oil (LO), HFD + HIIT, HFD + HIIT + LO. In the HIIT groups, rats ran on a treadmill, 4 days.week⁻¹. Erythrocyte n-3 PUFA content, body composition, inflammation, and intestinal mucosa-associated microbiota composition were assessed after 12 weeks. LO supplementation enhanced α-linolenic acid (ALA) to docosahexaenoic acid (DHA) conversion in erythrocytes, and HIIT potentiated this conversion. Compared with HFD, HIIT limited weight gain, fat mass accumulation, and adipocyte size, whereas LO reduced systemic inflammation. HIIT had the main effect on gut microbiota β-diversity, but the HIIT + LO association significantly increased Oscillospira relative abundance. In our conditions, HIIT had a major effect on body fat mass, whereas HIIT + LO improved ALA conversion to DHA and increased the abundance of Oscillospira bacteria in the microbiota.     

Validation of a short questionnaire to qualitatively assess the intake of total fat, saturated, monounsaturated, polyunsaturated fatty acids, and cholesterol

Background To validate a self‐administered 20‐item short questionnaire (SQ) for classifying individuals according to their intake of total fat, saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA), as well as cholesterol. Methods The SQ was sent to a randomly selected subsample of 300 participants of the European Prospective Investigation into Cancer and Nutrition (EPIC) in Heidelberg. The SQ was sent back by 244 participants (52.5% women, 47.5% men). Intake of total fat, SFA, MUFA, PUFA, and cholesterol was calculated from a 148‐item food frequency questionnaire (FFQ). The intake was compared with the scores computed from the SQ. Results Spearman's correlation coefficient between the intake estimated from the FFQ and the score from the SQ ranged from r = 0.29 (PUFA) to r = 0.56 (cholesterol). When the participants were assigned to quartiles of intake according to both methods 29–42% were classified into the same quartile, 1–7% of the participants were grossly misclassified. Conclusions The SQ demonstrated a good validity with respect to SFA and cholesterol and an acceptable validity with respect to total fat and MUFA, while the results are less good for PUFA. The SQ can be used to classify persons according to their intake into categories of intake.     

脂肪酸构成对兔主动脉粥样硬化形成的作用

目的 :　探讨防治动脉粥样斑形成的膳食脂肪酸构成 (饱和∶单不饱和∶多不饱和脂肪酸 )并从血脂代谢上阐释其机制。方法 :　 3 1只雄性兔分为脂肪酸构成 1∶ 1∶ 1 (I)、1∶ 1 .7∶1 .2 (II)、1∶ 1 .7∶ 2 .3 (III)的高脂组和对照组。喂养前、喂养第 44d和 77d测空腹血浆总甘油三酯(TG)、总胆固醇 (TC)、低密度脂蛋白胆固醇 (LDL-C)和高密度脂蛋白胆固醇 (HDL-C) ,第 77d处死动物 ,测定升主动脉粥样硬化斑块面积。结果 :　 (1 ) I、II、III组斑块面积 (mm2 )分别为 4.45±2 .3 8、6.0 9± 2 .73和 3 .90± 1 .68,III组显著低于 II组 (P<0 .0 5 ) ;(2 )喂养第 77d III组兔空腹血浆 TG为 0 .63± 0 .2 5 mmol/L显著低于 I组 1 .0 1± 0 .3 8和 II组 1 .2 4± 1 .1 7(P<0 .0 5 ) ,III组HDL-C/TG为 3 .68± 1 .69mmol/L,显著高于 I、II组的 2 .72± 1 .3 8和 2 .76± 1 .5 3 (P<0 .0 5 ) ,III组血浆 TG77d的累积浓度明显小于 I、II组 (P<0 .0 5 )。结论 :　 1∶ 1 .7∶ 2 .3膳食脂肪酸构成能降低血浆 TG和升高 HDL-C/TG,具有抗主动脉粥样硬化的作用     

Low fat and high monounsaturated fat diets decrease human low density lipoprotein oxidative susceptibility in vitro

Oxidative modification of low density lipoprotein (LDL) is thought to play an important role in the development of atherosclerosis. Some studies have found that LDL enriched in monounsaturated fatty acids (MUFA) are less susceptible to oxidation than LDL enriched in polyunsaturated fatty acids (PUFA). A high MUFA diet is an alternative to a lower-fat blood cholesterol-lowering diet. Less is known about the effects of high MUFA versus lower-fat blood cholesterol-lowering diets on LDL oxidative susceptibility. The present study was designed to evaluate the effects of men and women consuming diets high in MUFA (peanuts plus peanut butter, peanut oil and olive oil) on LDL oxidative susceptibility, and to compare these effects with those of a Step II blood cholesterol-lowering diet. A randomized, double-blind, five-period crossover design (n = 20) was used to study the effects of the following diets on LDL-oxidation: average American [35% fat, 15% saturated fatty acids (SFA)], Step II (25% fat, 7% SFA), olive oil (35% fat, 7% SFA), peanut oil (35% fat, 7% SFA) and peanuts plus peanut butter (35% fat, 8% SFA). The average American diet resulted in the shortest lag time (57 +/- 6 min) for LDL oxidized ex vivo, whereas the Step II, olive oil and peanuts plus peanut butter diets resulted in a lag time of 66 +/- 6 min (P < or = 0.1). The slower rate of oxidation [nmol dienes/(min x mg LDL protein)] observed when subjects consumed the olive oil diet (24 +/- 2) versus the average American (28 +/- 2), peanut oil (28 +/- 2) and peanuts plus peanut butter diets (29 +/- 2; P < or = 0.05) was associated with a lower LDL PUFA content. The results of this study suggest that lower-fat and higher-fat blood cholesterol-lowering diets high in MUFA have similar effects on LDL oxidative resistance. In addition, our results suggest that different high MUFA sources varying in the ratio of MUFA to PUFA can be incorporated into a high MUFA diet without increasing the susceptibility of LDL to oxidation.     

Composition of Dietary Fat Source Shapes Gut Microbiota Architecture and Alters Host Inflammatory Mediators in Mouse Adipose Tissue

Background: Growing evidence shows that dietary factors can dramatically alter the gut microbiome in ways that contribute to metabolic disturbance and progression of obesity. In this regard, mesenteric adipose tissue has been implicated in mediating these processes through the elaboration of proinflammatory adipokines. In this study, we examined the relationship of these events by determining the effects of dietary fat content and source on gut microbiota, as well as the effects on adipokine profiles of mesenteric and peripheral adipocytes. Methods: Adult male C57Bl/6 mice were fed milk fat–based, lard‐based (saturated fatty acid sources), or safflower oil (polyunsaturated fatty acid)–based high‐fat diets for 4 weeks. Body mass and food consumption were measured. Stool 16S ribosomal RNA (rRNA) was isolated and analyzed via terminal restriction fragment length polymorphism as well as variable V3–4 sequence tags via next‐generation sequencing. Mesenteric and gonadal adipose samples were analyzed for both lipogenic and inflammatory mediators via quantitative real‐time polymerase chain reaction. Results: High‐fat feedings caused more weight gain with concomitant increases in caloric consumption relative to low‐fat diets. In addition, each of the high‐fat diets induced dramatic and specific 16S rRNA phylogenic profiles that were associated with different inflammatory and lipogenic mediator profiles of mesenteric and gonadal fat depots. Conclusions: Our findings support the notion that dietary fat composition can both reshape the gut microbiota and alter host adipose tissue inflammatory/lipogenic profiles. They also demonstrate the interdependency of dietary fat source, commensal gut microbiota, and inflammatory profile of mesenteric fat that can collectively affect the host metabolic state.     

An acute intake of a walnut-enriched meal improves postprandial adiponectin response in healthy young adults

A deficit in adiponectin plays an important causal role in insulin resistance and metabolic syndrome. We hypothesized that as seen during the fasting state, the intake of a walnut-enriched meal increased postprandial adiponectin. Twenty-one healthy white men followed a 4-week baseline diet and then consumed 3 fat-loaded meals that included 1 g fat/kg body weight (65% fat) according to a randomized crossover design: olive oil–enriched meal (22% saturated fatty acids [SFA], 38% monounsaturated fatty acids [MUFA], 4% polyunsaturated fatty acids [PUFA]), butter-enriched meal (35% SFA, 22% MUFA, 4% PUFA), and walnut-enriched meal (20% SFA, 24% MUFA, 16% PUFA, and 4% α-linolenic acid). Leptin, resistin, adiponectin, and free fatty acids were determined at 0, 3, 6, and 8.5 hours after the fat load. After the walnut-enriched meal, plasma adiponectin concentrations were higher at 3 and 6 hours (P = .011, P = .046, respectively) compared with the butter-enriched meal and higher at 6 hours compared with the olive oil–enriched meal (P = .036). Free fatty acid levels decreased from baseline at 3 hours after the walnut-enriched meal (P = .001). No differences were observed between the 3 meals for leptin and resistin responses. Our data confirmed a beneficial profile in the postprandial response to walnuts, source of omega-3 PUFA with an increased postprandial adiponectin and lower postprandial free fatty acid responses. These findings suggest that the postprandial state is important for understanding the possible cardioprotective effects associated with omega-3 PUFA dietary fat.     

Dietary intake of fats and fatty acids in the Korean population: Korea National Health and Nutrition Examination Survey, 2013

BACKGROUND/OBJECTIVESThe aim of this study was to estimate average total fat and fatty acid intakes as well as identify major food sources using data from the Korea National Health and Nutrition Examination Survey (KNHANES) VI-1 (2013).SUBJECTS/METHODSTotal fat and fatty acid intakes were estimated using 24-hour dietary recall data on 7,048 participants aged ≥ 3 years from the KNHANES VI-1 (2013). Data included total fat, saturated fatty acid (SFA), monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), n-3 fatty acid (n-3 FA), and n-6 fatty acid (n-6 FA) levels. Population means and standard errors of the mean were weighted in order to produce national estimates and separated based on sex, age, income, as well as residential region. Major food sources of fat, SFA, MUFA, PUFA, n-3 FA, and n-6 FA were identified based on mean consumption amounts of fat and fatty acids in each food.RESULTSThe mean intake of total fat was 48.0 g while mean intakes of SFA, MUFA, PUFA, n-3 FA, and n-6 FA were 14.4 g, 15.3 g, 11.6 g, 1.6 g, and 10.1 g, respectively. Intakes of MUFA and SFA were each higher than that of PUFA in all age groups. Pork was the major source of total fat, SFA, and MUFA, and soybean oil was the major source of PUFA. Milk and pork were major sources of SFA in subjects aged 3-11 years and ≥ 12 years, respectively. Perilla seed oil and soybean oil were main sources of n-3 FA in subjects aged ≥ 50 years and aged < 50 years, respectively.CONCLUSIONSEstimation of mean fatty acid intakes of this study using nationally represented samples of the Korean population could be useful for developing and evaluating national nutritional policies.     

Dietary Fat and Polyunsaturated Fatty Acid Intakes during Childhood Are Prospectively Associated with Puberty Timing Independent of Dietary Protein

Dietary fat and fat quality have been inconsistently associated with puberty timing. The aim of this study was to investigate the prospective associations of dietary fat, saturated fatty acid (SFA), polyunsaturated fatty acid (PUFA), and monounsaturated fatty acid (MUFA) with puberty timing. Using longitudinal data from China Health and Nutrition Survey (CHNS) and Southwest China Childhood Nutrition and Growth (SCCNG) Study, we analyzed dietary data, anthropometric measurements, and potential confounders. Dietary intakes were assessed by 3-day 24-h recalls. Age at Tanner stage 2 for breast/genital development (B2/G2) and age at menarche/voice break (M/VB) were used as puberty development markers. Cox proportional hazard regression models were used to estimate the relevance of dietary intake of total fat, SFA, PUFA, and MUFA on puberty timing. Among 3425 girls and 2495 boys, children with higher intakes of total fat and PUFA were more likely to reach their B2/G2 or M/VB at an earlier age. Associations were not attenuated on additional adjustment for childhood dietary protein intake. However, higher intakes of SFA or MUFA were not independently associated with puberty development. A higher intake of dietary fat and PUFA in prepuberty was associated with earlier puberty timing, which was independent of dietary protein intake.     

Pork fat and chicken fat similarly affect plasma lipoprotein metabolism in cynomolgus monkeys fed diets with adequate levels of linoleic acid

The effects on plasma lipoprotein metabolism of replacing pork fat (PF) with chicken fat (CF) (formulated as part of currently recommended prudent diets) was evaluated in 10 male cynomolgus monkeys. Monkeys were rotated through three dietary periods, (each of 10-wk duration), during which total cholesterol (TC), triacylglycerol (TG) and HDL-cholesterol (HDL-C) were measured (7, 8 and 9 wk) and in vivo lipoprotein metabolism evaluated (after 9 wk). Initially, all monkeys were fed a high-fat, high-cholesterol reference diet [38% of energy (en) from fat, 18%en saturated fatty acids (SFA), 10%en monounsaturated fatty acids (MUFA), 10%en polyunsaturated fatty acids (PUFA), 0.045 mg cholesterol/kJ diet]. Subsequently, monkeys were rotated through two test diets (30%en fat, SFA/MUFA/PUFA 1:1:1, 0.004-0.005 mg cholesterol/kJ diet), in which 80% of the fat was either PF or CF, with the remaining 20% derived from high-linoleic safflower oil. There was no significant difference between the two test diets for TG, TC, nonHDL-C, HDL-C or the ratio of TC/HDL-C. Lipoprotein composition, LDL apolipoprotein B pool size, fractional catabolic rate and transport rate were also not significantly different when monkeys consumed the two test diets. These data suggest that when incorporated into diets following current guidelines and containing adequate PUFA ( approximately 7-9%en), PF and CF similarly affect plasma lipids.     

Immunological effects of low-fat diets with and without weight loss

OBJECTIVE: The immunologic effects of isocaloric reduced- and low-fat diets and a voluntary calorie-restricted low-fat diet resulting in weight loss were compared to the immunologic effects of an average American diet in hyperlipidemic individuals. METHODS: Ten hyperlipidemic subjects were studied during three six-week weight maintenance phases: baseline (BL) [35% fat [14% saturated fat (SFA), 13% monounsaturated fat (MUFA), 8% polyunsaturated fat (PUFA)] and 147 mg cholesterol (C)/1000 kcal], reduced-fat (RF) [26% fat (4% SFA, 11% MUFA, 11% PUFA) and 45 mg C/1000 kcal], and low-fat (LF) [15% fat (5% SFA, 5% MUFA, 3% PUFA) and 35 mg C/1000 kcal] diets followed by 12-week, low-fat calorie reduced phase (LFCR). RESULTS: During the last phase, the subjects' weight significantly decreased (p = 0.005). Cholesterol levels were significantly reduced during all phases, compared to BL diet (p < 0.05). Delayed-type hypersensitivity (DTH) was assessed using Multi-test CMI. Maximum induration diameters were 22.7, 25.4, 30.5, 34.5 mm for BL, RF, LF and LFCR diets, respectively. Subjects on the LFCR diets had significantly higher DTH compared to the BL diet (p = 0.005). No significant effect of diet was observed on lymphocyte proliferation or interleukin (IL)-1, IL-2 and prostaglandin (PG) E(2) production. CONCLUSIONS: These data suggest that low-fat diets (15% energy), under conditions which result in weight loss, do not compromise and may enhance the immune response of middle-aged and elderly hyperlipidemic subjects. The results of this study provide support for the hypothesis that moderate caloric restriction in humans may have a beneficial effect on cell-mediated immunity such as those reported in calorie-restricted rodents.     

Acute effects of meal fatty acid composition on insulin sensitivity in healthy post-menopausal women

Postprandial plasma insulin concentrations after a single high-fat meal may be modified by the presence of specific fatty acids although the effects of sequential meal ingestion are unknown. The aim of the present study was to examine the effects of altering the fatty acid composition in a single mixed fat-carbohydrate meal on glucose metabolism and insulin sensitivity of a second meal eaten 5 h later. Insulin sensitivity was assessed using a minimal model approach. Ten healthy post-menopausal women underwent four two-meal studies in random order. A high-fat breakfast (40 g fat) where the fatty acid composition was predominantly saturated fatty acids (SFA), n-6 polyunsaturated fatty acids (PUFA), long-chain n-3 PUFA or monounsaturated fatty acids (MUFA) was followed 5 h later by a low-fat, high-carbohydrate lunch (5.7 g fat), which was identical in all four studies. The plasma insulin response was significantly higher following the SFA meal than the other meals after both breakfast and lunch (P<0.006) although there was no effect of breakfast fatty acid composition on plasma glucose concentrations. Postprandial insulin sensitivity (SI(Oral)) was assessed for 180 min after each meal. SI(Oral) was significantly lower after lunch than after breakfast for all four test meals (P=0.019) following the same rank order (SFA < n-6 PUFA < n-3 PUFA < MUFA) for each meal. The present study demonstrates that a single meal rich in SFA reduces postprandial insulin sensitivity with 'carry-over' effects for the next meal.     

The cholesterolaemic effects of dietary fats in cholesteryl ester transfer protein transgenic mice.

In order to investigate the role of cholesteryl ester transfer protein (CETP) in the cholesterolaemic response to dietary fats, we analysed plasma lipid profiles of CETP-transgenic and control C57BL/6 mice fed standard chow (AIN-93G; AIN), a low-fat diet, and diets high in butter (saturated fatty acids; SFA), high-oleic acid safflower oil (monounsaturated fatty acids; MUFA), and safflower oil (polyunsaturated fatty acids; PUFA) for 5 weeks. Each group contained four or five mice. There were significant diet and dietxgenotype effects on plasma total cholesterol (TC; and respectively), liver TC ( and respectively), and esterified cholesterol (EC; and respectively); diet effects on plasma triacylglycerol liver free cholesterol and body weight a genotype effect on body-weight gain and a dietxgenotype effect on energy intake In transgenic mice the SFA diet caused significantly higher plasma TC than the PUFA diet In control mice MUFA and PUFA diets, but not the SFA diet, caused significantly higher plasma TC than the low-fat and AIN diets Transgenic mice fed PUFA had lower plasma TC while transgenic mice fed MUFA had lower LDL+VLDL-cholesterol than controls in the same dietary groups. Transgenic mice fed MUFA and PUFA diets also had significantly higher liver TC and respectively) and EC and respectively) than controls fed the same diets. In the present study we showed that: (1) CETP transgenic mice had a cholesterolaemic response to dietary fats similar to that in human subjects; (2) CETP transgenic mice fed PUFA showed significantly lower plasma TC, while those fed MUFA had lower LDL+VLDL-cholesterol than controls; (3) hepatic accumulation of cholesterol, possibly resulting from the combination of the enhanced cholesteryl ester transfer to apolipoprotein B-containing lipoproteins and increased hepatic uptake of cholesterol, may contribute to the cholesterol-lowering effect of MUFA and PUFA in CETP-transgenic mice; (4) CETP may play a role in appetite and/or energy regulation.     

A review of the evidence for the effects of total dietary fat, saturated, monounsaturated and n-6 polyunsaturated fatty acids on vascular function, endothelial progenitor cells and microparticles

Vascular dysfunction is recognised as an integrative marker of CVD. While dietary strategies aimed at reducing CVD risk include reductions in the intake of SFA, there are currently no clear guidelines on what should replace SFA. The purpose of this review was to assess the evidence for the effects of total dietary fat and individual fatty acids (SFA, MUFA and n-6 PUFA) on vascular function, cellular microparticles and endothelial progenitor cells. Medline was systematically searched from 1966 until November 2010. A total of fifty-nine peer-reviewed publications (covering fifty-six studies), which included five epidemiological, eighteen dietary intervention and thirty-three test meal studies, were identified. The findings from the epidemiological studies were inconclusive. The limited data available from dietary intervention studies suggested a beneficial effect of low-fat diets on vascular reactivity, which was strongest when the comparator diet was high in SFA, with a modest improvement in measures of vascular reactivity when high-fat, MUFA-rich diets were compared with SFA-rich diets. There was consistent evidence from the test meal studies that high-fat meals have a detrimental effect on postprandial vascular function. However, the evidence for the comparative effects of test meals rich in MUFA or n-6 PUFA with SFA on postprandial vascular function was limited and inconclusive. The lack of studies with comparable within-study dietary fatty acid targets, a variety of different study designs and different methods for determining vascular function all confound any clear conclusions on the impact of dietary fat and individual fatty acids on vascular function.     

脂肪酸组成对化学物诱导的结肠癌变危险性机理的研究

大鼠喂以含１５％脂肪,但是脂肪酸组成不一致的５组半合成饲料,实验期给以甲基亚硝基脲诱导结肠肿瘤,观察脂肪组成对处于增生危险的大鼠结肠粘膜的增生细胞核抗原（ＰＣＮＡ）、碱性磷酸酶活性（ＡＬＰ）、膜脂流动性、前列腺素Ｅ２（ＰＧＥ２）及细胞动力学的影响。结果表明：含饱和脂肪酸和单不饱和脂肪酸成分最少而含ｎ－６多不饱和脂肪酸（ＰＵＦＡ）成分最高的第３组,ＰＣＮＡ和ＰＩ标志的Ｓ期细胞数最多,ＡＬＰ活性较高;含ｎ－３ＰＵＦＡ比例最高的第４组,ＰＣＮＡ和ＰＩ标志的Ｓ期细胞数、ＡＬＰ活性及ＰＧＥ２含量最少,而膜脂流动性最好。结果提示,含ｎ－３ＰＵＦＡ较高比例的脂肪酸组成降低由化学物诱导的结肠癌变危险性,其机制之一可能是,通过减少结肠粘膜ＰＣＮＡ、ＰＩ标志的Ｓ期细胞数、ＡＬＰ活性、保护膜脂流动性及减少ＰＧＥ２生成等进行。     

Chronic effects of a high-fat diet enriched with virgin olive oil and a low-fat diet enriched with alpha-linolenic acid on postprandial endothelial function in healthy men

Traditional cardiovascular risk factors are associated with endothelial dysfunction. The vascular endothelium plays a key role in local vascular tone regulation and can be modulated by dietary fat. We propose to determine the chronic effect of three diets with different fat compositions on postprandial endothelial function and inflammatory biomarkers. Twenty healthy men followed three 4-week diets in a randomised cross-over design: a Western diet, rich in saturated fat (22% SFA, 12% MUFA and 0.4% alpha-linolenic acid (ALA), all fractions are % of energy); a Mediterranean diet, rich in MUFA ( < 10 % SFA, 24 % MUFA and 0.4% ALA); a low-fat diet enriched in ALA ( < 10% SFA, 12% MUFA and 2% ALA). At the end of each dietary period all subjects underwent a postprandial study. Plasma concentrations of lipid parameters, soluble intercellular cell-adhesion molecule-1, soluble vascular cell-adhesion molecule-1 (sVCAM-1), nitrates and nitrites (NOx) and endothelial function studied by laser Doppler were examined at 0, 2, 4, 6 and 8 h. The endothelium-dependent vasodilatory response was greater 4 h after the ingestion of the MUFA-rich diet than after the SFA or ALA low-fat diets (P = 0.031). The 4 h postprandial plasma sVCAM-1 levels were lower after the MUFA meals than after the ALA low-fat diet (P = 0.043). The bioavailability of NOx was higher following the MUFA diet than after the SFA and ALA low-fat diets (P = 0.027). We found no differences in the other parameters measured. Chronic ingestion of a Mediterranean diet avoids the postprandial deterioration of endothelial function associated with Westernised diets in healthy individuals.     

Total fat and fatty acid intakes and food sources in Mediterranean older adults requires education to improve health

The proportion of fat has increased at the expense of carbohydrates in the past years, and we aimed to assess total fat and fatty acids intake and their food sources among Mediterranean older adults and compare them to national and international recommendations. This study was conducted in 211 participants to determine lipid and fatty acid intake using a Spanish food database. The mean daily intake of lipids was 68.6 g/d (standard deviation [SD]: 24.6; 34.4%, SD: 7.0 of total energy consumed). Men, younger participants, and those with higher education ingested more lipids than their peers. Fatty acids were ingested as follows (expressed as percentage of total energy intake): monounsaturated fatty acids (MUFA) (16.7%, SD: 4.1), saturated fatty acids (SFA) (9.6%, SD: 2.6), and polyunsaturated fatty acids (PUFA) (5.0%, SD: 1.7). Oils and seeds were the highest contributors in the intake of lipids (38.8%, SD: 16.0), MUFA (53.9%, SD: 18.7), and PUFA (33.0%, SD: 16.4). The total fat intake (34.4%, SD: 7.0) was within the range of International and Spanish recommendations among Mediterranean older adults; however, the intake of fatty acids did not abide by the international (PUFA) and Spanish recommendations (SFA, MUFA). α-Linoleic acid, eicosapentaenoic acid, and docosahexaenoic acid intake were lower than recommendations, but cholesterol intake (243.9 mg, SD: 140.4) was within the range of recommendations. Therefore, public health campaigns are needed to encourage older adults to decrease SFA intake and increase adherence to the Mediterranean diet pattern for a better health.     

Dietary mono- and polyunsaturated fatty acids similarly increase plasma apolipoprotein A-IV concentrations in healthy men and women

We investigated the effect of dietary fatty acid composition on plasma apolipoprotein (apo) A-IV concentrations. Plasma apo A-IV concentrations were measured by ELISA in plasma of 48 healthy men and women in a controlled dietary study. First, all participants consumed a 2-wk baseline diet rich in saturated fatty acids (SFA). Then, they were randomly assigned to one of three dietary treatments, which contained refined olive oil [rich in monounsaturated fatty acids (MUFA), n = 17], rapeseed oil [rich in MUFA and alpha-linolenic acid [18:3(n-3)], n = 13], or sunflower oil [rich in (n-6) PUFA, n = 18] as the principal source of fat for 4 wk. The plasma concentrations of apo A-IV increased when subjects consumed the diets rich in unsaturated fatty acids, by 16% or 13.0 mg/L [F((2,76)) = 12.874, P < 0.001 by repeated-measures ANOVA]. The increase was not affected by diet group affiliation, gender or apo A-IV genotype. In conclusion, diets rich in unsaturated fatty acids, independent of the degree of unsaturation, gender and apo A-IV genotype, increase plasma apo A-IV concentrations compared with a baseline diet rich in SFA in healthy men and women.     

Effect of substituting saturated with monounsaturated fatty acids on serum visfatin levels and insulin resistance in overweight women: A randomized cross-over clinical trial

Objective: This study aimed to determine the effects of a monounsaturated fatty acids (MUFA)-rich diet on serum visfatin, interleukin-6 and insulin levels among overweight women. Design: In this randomized cross-over clinical trial, 17 premenopausal overweight women were included. Participants were randomly assigned to consume either a hypocaloric, saturated fatty acids (SFA)-rich diet (16% SFA and 8% MUFA) or a hypocaloric, MUFA-rich diet (16% MUFA and 8% SFA) for 12 weeks crossing over after a 2-week washout period. Percentages of energy from other macronutrients were similar between the two diets. Biochemical and anthropometric assessments were done at the first and at the end of each period. Statistical analyses were done using paired t-test. In all statistical analysis, p < 0.05 was considered as significant. Results: The participant's mean body mass index was 27.6 kg/m². Mean percentages of MUFA intake were 13% during MUFA-rich diet and 7% during SFA-rich diet. The corresponding values for SFA intake were 8.5% and 14%, respectively. We failed to find any significant differences between two intervention diets in terms of their effect on the serum levels of IL-6, visfatin and insulin. However, serum visfatin and IL-6 levels increased during the SFA-rich diet (0.4 ± 0.4 ng/ml and 0.19 ± 0.3 pg/ml, respectively) and decreased during the MUFA-rich diet ( ? 0.7 ± 0.5 ng/ml and ? 0.17 ± 0.3 pg/ml, respectively). In spite of a slight reduction in both periods, changes in serum insulin levels did not reach significant levels comparing the two periods. Conclusions: Our findings did not support any significant effect of a MUFA-rich intake on serum IL-6 and insulin levels as compared with a SFA-rich diet; however, it has the potential to favourably affect serum visfatin levels.