Roundtable discussion: Dietary fats in prevention of atherosclerotic cardiovascular disease

This roundtable discussion on dietary fats was inspired by a recent Presidential Advisory from the American Heart Association giving recommendations about dietary fats for prevention of atherosclerotic cardiovascular disease. The Advisory clarifies a long-held position that saturated fat should be reduced in the American diet. New studies and meta-analyses have questioned the adverse role of saturated fat. The Advisory adds a crucial clarification based primarily on 4 randomized controlled diet trials, each conducted over 4 to 8 years during the 1960s extending to the 1970s. In each trial, saturated fat was reduced and replaced by vegetable oil rich in polyunsaturated fat (PUFA). Meta-analysis showed 29% reduction in major coronary events in the groups receiving PUFAs. Randomized clinical trials provide the best kind of evidence. Replacing saturated fat with PUFA reduces cardiovascular events. Replacing saturated fats with carbohydrates or trans fats does not reduce cardiovascular events. Cardiovascular risk reduction has also been seen in randomized trials with monounsaturated fat in the context of whole food diets, mostly plant based (Mediterranean diets). In this discussion, we additionally cover some of the roller-coaster history of recommendations concerning dietary fat and provide advice for practical counseling.     

Review of the evidence for the potential impact and feasibility of substituting saturated fat in the New Zealand diet

Objective: To estimate the potential impact on cardiovascular health of modifying dietary intake of saturated fat across the New Zealand population, and whether this would be appropriate and feasible. Methods: First, a literature review of meta‐analyses was conducted to estimate the magnitude of reduction in risk for cardiovascular events in response to a reduction in dietary saturated fat intake (with or without substitution with other macronutrients). Second, data from the New Zealand Adult Nutrition Survey 2008/09 were used to determine whether a change to the population's dietary fat intake would be warranted and feasible. Results: Five relevant meta‐analyses were identified. No significant association between saturated fat intake alone and cardiovascular disease was found. However, the incidence of cardiovascular disease events was less when dietary saturated fats were replaced with polyunsaturated fats, reducing the risk of cardiovascular events by about 10%. Compared with nutritional guidelines, New Zealanders’ current saturated fat intake is excessive while polyunsaturated fat intake is inadequate; both would be corrected by a substitution of 5% of daily energy intake. Conclusions: Replacing 5% of daily energy consumed as saturated fat with polyunsaturated fats would be expected to reduce cardiovascular events by about 10%. Implications: In order to achieve the population‐wide dietary fat modifications needed to improve cardiovascular health for New Zealanders, a public health strategy (e.g. fiscal, regulatory and/or educational interventions) must be implemented. Further work is needed to establish the cost‐effectiveness of the various strategies.     

Nutrition,sensory evaluation,and performance analysis of hydrogenated frying oils

The Food and Drug Administration now requires labeling of trans fats on nutrition labels, a decision that has created a push to reformulate deep-fat frying oils. Prior to the passage of this law, frying oils contained trans fats because trans fats made the oils more stable and thus allowing for longer frying usage. In the present study, oil performance, sensory evaluation and nutritional analysis was conducted on trans fat-free oils through a 10-day degradation process using French fries to break down the oil. The goal of the study was to test oil stability and nutrition analysis and to learn consumer preference between trans fat and trans fat-free oils. Sensory evaluation indicated a preference for fries composed from trans fat-free oil mixtures. The most stable oils were also combination oils. Based on these findings, industry representatives considering using the trans fat-free frying oils should consider using blended oils instead, which met customers’ taste preference and minimized oil rancidity and usage.     

NMR-determined lipoprotein subclass profile is associated with dietary composition and body size

Background and aims

Dyslipidemia is influenced by diet and body habitus. The Nuclear Magnetic Resonance spectroscopy lipoprotein subclass profile (NMR-LSP) is associated with diabetes and its vascular complications; and an NMR-LSP featuring large VLDL particles and small LDL and HDL particles is linked with cardiovascular disease (CVD). Thus interventions which favourably modify NMR-LSP may reduce risk for diabetes, its complications and CVD. The study aim was to investigate the associations between NMR-LSP, dietary composition and body size measures using data from the Melbourne Collaborative Cohort Study (MCCS).

Methods and results

NMR-LSP was assessed in 313 men and 403 women (median age 54 years) randomly selected from a community-based cohort study. Diet was assessed using a specifically developed food frequency questionnaire (FFQ), and body size was assessed by body mass index (BMI) or waist:hips ratio (WHR). To simplify the 15 NMR-LSP variables, factor analysis was used to derive a single factor. Multivariate linear regression with this factor score as the dependent variable demonstrated that in men, total PUFA and n-6 dietary fat intake and BMI were associated with a more atherogenic NMR-LSP pattern; while in women dietary glycemic index and WHR demonstrated positive associations, and n-3 fat intake an inverse association.

Conclusions

We developed a single factor score to summarize the NMR-LSP that has the benefit of combining all aspects of the NMR-LSP and accounting for correlations between them. We have shown correlations between the NMR-LSP and body size and dietary composition.     

Non-invasive assessment of hepatic lipid subspecies matched with non-alcoholic fatty liver disease phenotype

Background and aimsNonalcoholic fatty liver disease (NAFLD) is characterized by excessive hepatic fat accumulation. Increased hepatic saturated fats and decreased hepatic polyunsaturated fats may be particularly lipotoxic, contributing to metabolic dysfunction. We compared hepatic lipid subspecies in adults with and without NAFLD, and examined links with hallmark metabolic and clinical characteristics of NAFLD.Methods and resultsNineteen adults with NAFLD (total hepatic fat:18.8 ± 0.1%) were compared to sixteen adults without NAFLD (total hepatic fat: 2.1 ± 0.01%). ¹H-MRS was used to assess hepatic lipid subspecies. Methyl, allylic, methylene, and diallylic proton peaks were measured. Saturation, unsaturation, and polyunsaturation indices were calculated. Whole-body phenotyping in a subset of participants included insulin sensitivity (40 mU/m² hyperinsulinemic-euglycemic clamps), CT-measured abdominal adipose tissue depots, exercise capacity, and serum lipid profiles. Participants with NAFLD exhibited more saturated and less unsaturated hepatic fat, accompanied by increased insulin resistance, total and visceral adiposity, triglycerides, and reduced exercise capacity compared to controls (all P < 0.05). All proton lipid peaks were related to insulin resistance and hypertriglyceridemia (P < 0.05).ConclusionParticipants with NAFLD preferentially stored excess hepatic lipids as saturated fat, at the expense of unsaturated fat, compared to controls. This hepatic lipid profile was accompanied by an unhealthy metabolic phenotype.     

Nutrition and physical activity in Asian Indians with non-alcoholic fatty liver: A case control study

AimWe tested the hypothesis that Asian Indians with non-alcoholic fatty liver disease (NAFLD) would have imbalanced diets and lower intensity of physical activity than those without NAFLD.MethodsWe studied dietary intake, intensity of physical activity and anthropometric and metabolic profiles in subjects with NAFLD and in healthy controls. Complete clinical, biochemical, dietary and physical activity profiles were studied for 169 cases and 173 controls in a prospective manner. Bivariate and multivariate analyses were carried out to identify the predictors of NAFLD [odds ratio (OR) and 95% confidence intervals (95%CI)].ResultsThe mean dietary intakes of total energy, carbohydrate, protein, total fat, saturated fat and total cholesterol were significantly higher, while intake of monounsaturated fatty acids and polyunsaturated fatty acids was significantly lower in cases as compared to controls (p < 0.01 for all). Further, mean physical activity in a day (expressed as MET.Minutes) and total energy expenditure were significantly lower in cases than in controls (33.3 ± 3.6 vs.36.2 ± 0.5, p = 0.001 and 2707.6 ± 505.6 vs. 2904.3 ± 690.3, p = 0.02, respectively). On multivariate analysis, percentage dietary total fat intake (OR: 13.4; 95% CI: 4.6–39.3, p = 0.001), homeostatis model assessment for insulin resistance (OR: 6.9; 95% CI: 3.2–14.8, p = 0.001) abdominal obesity (OR: 2.7; 95% CI: 1.5–5.0, p = 0.001) and high serum triglycerides (OR: 2.1; 95%CI: 1.2–3.8, p = 0.007) were associated with an increased risk for development of NAFLD.ConclusionDecrease in intake of total dietary fats and improvement of insulin resistance, abdominal obesity and blood triglycerides should be important measures for management of NAFLD in Asian Indians in north India.     

健康体检报告分析

以近1年来来我院做健康体检的健康人为对象,了解健康人的血压、血糖、血脂等水平随性别、年龄、生活习惯等因素影响的变化规律,旨在倡导健康的生活方式,预防血压、血糖、血脂异常而导致心脑血管病的发生.     

血尿酸、血脂检测在2型糖尿病及其并发血管病变中的意义

目的：探讨血尿酸（SUA）、血脂与2型糖尿病（T2DM）及其并发血管病变的关系.方法：选取我院2008年6月至2009年6月收治的40例2型糖尿病并发血管病变患者（A组）、30例2型糖尿病无血管病变患者（B组）及30例健康对照组（C组）为研究对象,分别测定三组的血尿酸及血脂水平,并进行统计分析.结果：A组患者的SUA、甘油三脂（TG）、胆固醇（TC）、低密度脂蛋白胆固醇（LDL-C）显著高于B、C两组,P〈0.05.A组患者的高密度脂蛋白胆固醇（HDL-C）显著低于B、C两组,P〈0.05.B组患者的TG、TC显著高于C组,P〈0.05.结论：T2DM患者常伴有SUA及血脂的异常,其可作为T2DM并发血管病变的检测指标.     

参芪复方对自发性糖尿病肾病大鼠血糖、血脂及血清CRP、IL-6的影响

目的：观察参芪复方对自发性早期糖尿病肾病大鼠血糖、血脂及血清CRP、IL-6的影响,并探讨参芪复方进行短期干预的可能机制。方法：SPF级雄性GK大鼠60只,随机选取10只GK大鼠作为空白对照组,高脂饲料进行造模,造模成功后随机分为中药高、低剂量组,西药组和模型组。分别用不同剂量参芪复方混悬液,雷米普利悬液,无菌水进行灌喂,每4周测定空腹血糖一次。8周后,测定各组大鼠空腹血糖、血总胆固醇（TC）、甘油三酯（TG）、血清CRP、IL-6水平。结果：与空白组和各治疗组相比,模型组大鼠血清空腹血糖、TC、TG、CRP、IL-6显著升高（P〈0．01）,参芪复方高低剂量均能降低大鼠血清CRP、IL-6水平,并能改善糖脂代谢紊乱。结论：参芪复方能够有效改善实验性糖尿病肾病大鼠炎症反应,改善糖脂代谢,从而起到早期防治糖尿病肾病的作用。     

The ω-3 and ω-6 fats in meals: a proposal for a simple new label

Objective

The ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) are separate essential dietary fatty acids that play a key role in many physiologic processes in higher animals. The content of these PUFAs is relatively well described for many individual food components. Our goal in this study was to analyze the PUFA content of whole meals and produce a simple measurement to estimate the intake of these fatty acids.

Methods

The fatty acid profile and macronutrient composition were determined for a range of fast food, cuisine (restaurant-prepared), and home-prepared whole meals commonly consumed by Australians.

Results

Across the different meals there was significant variation in protein (4-fold), fat (13-fold), and carbohydrate (23-fold) contents. With regard to the fatty acid profile, saturated and monounsaturated fatty acids made up approximately 80% of total fatty acids for most meals. The ω-6 PUFAs were substantially more abundant than ω-3 PUFAs for most meals. The balance of dietary ω-3 and ω-6 PUFAs is an important determinant of their metabolic effects within the body, and accordingly we calculated the percentage of the total PUFA comprised of ω-3 PUFAs and referred to this as the PUFA Balance. This parameter showed the greatest variation among the different meals (>45-fold).

Conclusion

The relative proportions of ω-3 and ω-6 PUFAs vary greatly across meals. PUFA Balance is a useful tool that will allow individuals to more easily monitor and balance their intake of ω-3 and ω-6 fats.