Saturated and unsaturated fat diets impair hippocampal glutamatergic transmission in adolescent mice.

Consumption of high-fat diets (HFD) has been associated with neuronal plasticity deficits and cognitive disorders linked to the alteration of glutamatergic disorders in the hippocampus. As young individuals are especially vulnerable to the effects of nutrients and xenobiotics on cognition, we studied the effect of chronic consumption of saturated (SOLF) and unsaturated oil-enriched foods (UOLF) on: i) spatial memory; ii) hippocampal synaptic transmission and plasticity; and iii) gene expression of glutamatergic receptors and hormone receptors in the hippocampus of adolescent and adult mice. Our results show that both SOLF and UOLF impair spatial short-term memory. Accordingly, hippocampal synaptic plasticity mechanisms underlying memory, and gene expression of NMDA receptor subunits are modulated by both diets. On the other hand, PPARγ gene expression is specifically down-regulated in adolescent SOLF individuals and up-regulated in adult UOLF mice.

Overfeeding Saturated Fat Increases LDL (Low-Density Lipoprotein) Aggregation Susceptibility While Overfeeding Unsaturated Fat Decreases Proteoglycan-Binding of Lipoproteins.

Objective: We recently showed that measurement of the susceptibility of LDL (low-density lipoprotein) to aggregation is an independent predictor of cardiovascular events. We now wished to compare effects of overfeeding different dietary macronutrients on LDL aggregation, proteoglycan-binding of plasma lipoproteins, and on the concentration of oxidized LDL in plasma, 3 in vitro parameters consistent with increased atherogenicity. Approach and Results: The participants (36 subjects; age, 48+/-10 years; body mass index, 30.9+/-6.2 kg/m2) were randomized to consume an extra 1000 kcal/day of either unsaturated fat, saturated fat, or simple sugars (CARB) for 3 weeks. We measured plasma proatherogenic properties (susceptibility of LDL to aggregation, proteoglycan-binding, oxidized LDL) and concentrations and composition of plasma lipoproteins using nuclear magnetic resonance spectroscopy, and in LDL using liquid chromatography mass spectrometry, before and after the overfeeding diets. LDL aggregation increased in the saturated fat but not the other groups. This change was associated with increased sphingolipid and saturated triacylglycerols in LDL and in plasma and reduction of clusterin on LDL particles. Proteoglycan binding of plasma lipoproteins decreased in the unsaturated fat group relative to the baseline diet. Lipoprotein properties remained unchanged in the CARB group. Conclusions: The type of fat during 3 weeks of overfeeding is an important determinant of the characteristics and functional properties of plasma lipoproteins in humans.

Effects of Saturated Fat, Polyunsaturated Fat, Monounsaturated Fat, and Carbohydrate on Glucose-Insulin Homeostasis: A Systematic Review and Meta-analysis of Randomised Controlled Feeding Trials.

BACKGROUND: Effects of major dietary macronutrients on glucose-insulin homeostasis remain controversial and may vary by the clinical measures examined. We aimed to assess how saturated fat (SFA), monounsaturated fat (MUFA), polyunsaturated fat (PUFA), and carbohydrate affect key metrics of glucose-insulin homeostasis. METHODS AND FINDINGS: We systematically searched multiple databases (PubMed, EMBASE, OVID, BIOSIS, Web-of-Knowledge, CAB, CINAHL, Cochrane Library, SIGLE, Faculty1000) for randomised controlled feeding trials published by 26 Nov 2015 that tested effects of macronutrient intake on blood glucose, insulin, HbA1c, insulin sensitivity, and insulin secretion in adults aged ≥18 years. We excluded trials with non-isocaloric comparisons and trials providing dietary advice or supplements rather than meals. Studies were reviewed and data extracted independently in duplicate. Among 6,124 abstracts, 102 trials, including 239 diet arms and 4,220 adults, met eligibility requirements. Using multiple-treatment meta-regression, we estimated dose-response effects of isocaloric replacements between SFA, MUFA, PUFA, and carbohydrate, adjusted for protein, trans fat, and dietary fibre. Replacing 5% energy from carbohydrate with SFA had no significant effect on fasting glucose (+0.02 mmol/L, 95% CI = -0.01, +0.04; n trials = 99), but lowered fasting insulin (-1.1 pmol/L; -1.7, -0.5; n = 90). Replacing carbohydrate with MUFA lowered HbA1c (-0.09%; -0.12, -0.05; n = 23), 2 h post-challenge insulin (-20.3 pmol/L; -32.2, -8.4; n = 11), and homeostasis model assessment for insulin resistance (HOMA-IR) (-2.4%; -4.6, -0.3; n = 30). Replacing carbohydrate with PUFA significantly lowered HbA1c (-0.11%; -0.17, -0.05) and fasting insulin (-1.6 pmol/L; -2.8, -0.4). Replacing SFA with PUFA significantly lowered glucose, HbA1c, C-peptide, and HOMA. Based on gold-standard acute insulin response in ten trials, PUFA significantly improved insulin secretion capacity (+0.5 pmol/L/min; 0.2, 0.8) whether replacing carbohydrate, SFA, or even MUFA. No significant effects of any macronutrient replacements were observed for 2 h post-challenge glucose or insulin sensitivity (minimal-model index). Limitations included a small number of trials for some outcomes and potential issues of blinding, compliance, generalisability, heterogeneity due to unmeasured factors, and publication bias. CONCLUSIONS: This meta-analysis of randomised controlled feeding trials provides evidence that dietary macronutrients have diverse effects on glucose-insulin homeostasis. In comparison to carbohydrate, SFA, or MUFA, most consistent favourable effects were seen with PUFA, which was linked to improved glycaemia, insulin resistance, and insulin secretion capacity.

[Effect of fats on cardiovascular disease prevention in Denmark].

In Denmark death from cardiovascular disease (CVD) has decreased, mainly due to a 72% reduction since 1990 in death from ischaemic heart disease from reduced smoking, elimination of industrial trans fatty acids in the diet, and more effective medical treatment. Replacement of saturated fat by carbohydrate and/or n-6 polyunsaturated fat may increase CVD, but it is reduced by substitution with n-3 fats, monounsaturated fat, or low glycaemic index carbohydrates. Despite a high saturated fat content dark chocolate and cheese may reduce CVD and diabetes risk and eggs may be neutral, and less restrictive dietary recommendations are indicated.

Dietary lipid unsaturation influences survival and oxidative modifications of an amyotrophic lateral sclerosis model in a gender-specific manner.

The implication of lipid peroxidation in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) derive from high abundance of peroxidation-prone polyunsaturated fatty acids in central nervous system and its relatively low antioxidant content. In the present work, we evaluated the effect of dietary changes aimed to modify fatty acid tissular composition in survival, disease onset, protein, and DNA oxidative modifications in the hSODG93A transgenic mice, a model of this motor neuron disease. Both survival and clinical evolution is dependent on dietary fatty acid unsaturation and gender, with high unsaturated diet, leading to loss of the disease-sparing effect of feminine gender. This was associated with significant increases in protein carbonyl and glycoxidative modifications as well as non-nuclear 8-oxo-dG, a marker of mitochondrial DNA oxidation. Comparison of these data with γH2AX immunostaining, a marker of DNA damage response, suggests that the highly unsaturated diet-blunted mitochondrial-nuclear free radical dependent crosstalk, since increased 8-oxo-dG was not correlated with increased DNA damage response. Paradoxically, the highly unsaturated diet led to lower peroxidizability but higher anti-inflammatory indexes. To sum up, our results demonstrate that high polyunsaturated fatty acid content in diets may accelerate the disease in this model. Further, these results reinforce the need for adequately defining gender as a relevant factor in ALS models, as well as to use structurally characterized markers for oxidative damage assessment in neurodegeneration.

Saturated fat, carbohydrates and cardiovascular disease.

The dietary intake of saturated fatty acids (SAFA) is associated with a modest increase in serum total cholesterol, but not with cardiovascular disease (CVD). Replacing dietary SAFA with carbohydrates (CHO), notably those with a high glycaemic index, is associated with an increase in CVD risk in observational cohorts, while replacing SAFA with polyunsaturated fatty acids (PUFA) is associated with reduced CVD risk. However, replacing a combination of SAFA and trans-fatty acids with n-6 PUFA (notably linoleic acid) in controlled trials showed no indication of benefit and a signal toward increased coronary heart disease risk, suggesting that n-3 PUFA may be responsible for the protective association between total PUFA and CVD. High CHO intakes stimulate hepatic SAFA synthesis and conservation of dietary SAFA . Hepatic de novo lipogenesis from CHO is also stimulated during eucaloric dietary substitution of SAFA by CHO with high glycaemic index in normo-insulinaemic subjects and during hypocaloric high-CHO/low-fat diets in subjects with the metabolic syndrome. The accumulation of SAFA stimulates chronic systemic low-grade inflammation through its mimicking of bacterial lipopolysaccharides and÷or the induction of other pro-inflammatory stimuli. The resulting systemic low-grade inflammation promotes insulin resistance, reallocation of energy-rich substrates and atherogenic dyslipidaemia that concertedly give rise to increased CVD risk. We conclude that avoidance of SAFA accumulation by reducing the intake of CHO with high glycaemic index is more effective in the prevention of CVD than reducing SAFA intake per se.

Dietary fat and breast cancer risk in the European Prospective Investigation into Cancer and Nutrition.

BACKGROUND: Epidemiologic studies have produced conflicting results with respect to an association of dietary fat with breast cancer. OBJECTIVE: We aimed to investigate the association between fat consumption and breast cancer. DESIGN: We prospectively investigated fat consumption in a large (n = 319,826), geographically and culturally heterogeneous cohort of European women enrolled in the European Prospective Investigation into Cancer and Nutrition who completed a dietary questionnaire. After a mean of 8.8 y of follow-up, 7119 women developed breast cancer. Cox proportional hazard models, stratified by age and center and adjusted for energy intake and confounders, were used to estimate hazard ratios (HRs) for breast cancer. RESULTS: An association between high saturated fat intake and greater breast cancer risk was found [HR = 1.13 (95% CI: 1.00, 1.27; P for trend = 0.038) for the highest quintile of saturated fat intake compared with the lowest quintile: 1.02 (1.00, 1.04) for a 20% increase in saturated fat consumption (continuous variable)]. No significant association of breast cancer with total, monounsaturated, or polyunsaturated fat was found, although trends were for a direct association of risk with monounsaturated fat and an inverse association with polyunsaturated fat. In menopausal women, the positive association with saturated fat was confined to nonusers of hormone therapy at baseline [1.21 (0.99, 1.48) for the highest quintile compared with the lowest quintile; P for trend = 0.044; and 1.03 (1.00, 1.07) for a 20% increase in saturated fat as a continuous variable]. CONCLUSIONS: Evidence indicates a weak positive association between saturated fat intake and breast cancer risk. This association was more pronounced for postmenopausal women who never used hormone therapy.

Revisão de literatura: aspectos gerais do processo de fritura de imersão / Revision of literature: general aspects of the process of fritura of immersion

A fritura de imersão é uma operação importante por ser um processo rápido de preparação, de baixo custo, eficiente, utilizado em uma ampla variedade de alimentos e por conferir aos alimentos características únicas de odor e sabor. O mecanismo de fritura é bastante simples: o óleo aquecido serve como meio de transferência de calor para o alimento que se frita. Como conseqüência, o calor converte a água do interior do alimento em vapor e também funde a sua gordura. O vapor e a gordura, escapam do interior para o exterior do alimento até atingirem o óleo. O inverso, é que parte do óleo de fritura é absorvida pelo alimento. Muitos fatores influenciam a qualidade do alimento que se irá obter; entre eles, destacam-se o óleo empregado, a natureza do alimento e as condições do processo. O desconhecimento das condições acima citadas poderá ocasionar uma maior absorção do óleo pelo alimento, aumentando sua densidade calórica, além das alterações organoléptica, químicas e físicas que poderão repercutir em transtornos para a saúde do consumidor. Esta revisão tem como objetivo, descrever e discutir o complexo processo de fritura, suas implicações para a saúde e as atuais regulamentações sobre o tema.

Efecto de dietas suplementadas con ácidos grasos saturados o pliinsaturados sobre parametros hematológicos hemostáticos y lipoproteicos: relación con modificaciones histológicas en aorta torácica y abdominal en conejos / Effect of diets containing saturated fatty acids upon hematological hemostatic and lipoprotein parameters and relationship with histological modifications in the rabbit thoracic and abdominal aorta

El consumo experimental de ácidos grasos saturados induce el aumento de marcadores hemostáticos, hamatológicos y lipoproteicos que faciltan el desarrollo de aterosclerosis, mientras que los ácidos grasos insaturados producen el efecto opuesto. El propósito de este estudio fue investigar, en conejos, el efecto de la administración durante 4 meses de dos tipos de dietas: 1) Enriquecida con ácidos grasos saturados con una relación insaturada: saturadas (I:S) de 1,05 y otra dieta, 2) Enriquecida con ácidos grasos insaturados con una relación I:S = 6,9, sobre parámetros bioquímicos, hematológicos y hemostáticos asociados con la coagulación, la agregación plaquetaria y su relaciones con las modificaciones histológicas en la aorta torácica y abdominal. Los resultados demuestran que la administración de dos tipos de dietas, no modificó los parámetros hemetológicos y hemostáticos, pero si hubo cambios significativos en los lípidos plasmáticos: aumento en la concentración de colesterol total en los dos grupos que recibieron la dieta con los aceites, aumento en la HDLc en los conejos alimentados con la dieta enriquecida con ácidos grasos saturados, e incremento en los triglicéridos en los animales que recibieron la dieta suplementada con ácidos grasos insaturados. Las modificaciones histológicas en la aorta torácica y abdominal son compatibles con lesiones ateroscleróticas: alteración de la íntima, infiltración lipídica, trombosis y calcificacioón de la media. Estas lesiones fueron más severas y frecuentes en el grupo de conejos que recibieron la dieta con alto contenido en ácidos grasos insaturados.

Dietary fat, fat subtypes, and breast cancer in postmenopausal women: a prospective cohort study.

BACKGROUND: The intake of total dietary fat and of certain fat subtypes has been shown to be strongly associated with breast cancer in international comparisons and in animal experiments. However, observational epidemiologic studies have generally reported either weak positive or no associations. To extend the prospective epidemiologic evidence on this question, we examined the association between adult dietary intake of fat, fat subtypes, and breast cancer in a large, prospective cohort of postmenopausal women. METHODS: Participants were selected from a national breast cancer mammography screening program conducted from 1973 through 1981 at 29 centers throughout the United States. From 1987 through 1989, 40022 postmenopausal women satisfactorily completed a mailed, self-administered questionnaire that included a 60-item National Cancer Institute/Block food-frequency questionnaire. Women were then followed for an average of 5.3 years; 996 women developed breast cancer. Risk was assessed by use of Cox proportional hazard regression, with age as the underlying time metric. All statistical tests were two-sided. RESULTS: Compared with women in the lowest quintile (Q1) of percentage of energy from total fat, the adjusted risk ratio (RR) and 95% confidence interval (CI) for women in the highest quintile (Q5) was 1.07 (95% CI = 0.86-1.32). In analyses stratified by history of benign breast disease (BBD), a positive association was observed among only women with no history of BBD (RR (Q5 versus Q1) = 2.20; 95% CI = 1.41-3.42; test for trend, P =.0003). The increased risk in these women appeared to be attributable to unsaturated fat intake and oleic acid in particular. CONCLUSIONS: In this study, there was no overall association between fat intake during adulthood and breast cancer risk; however, among women with no history of BBD, there appeared to be a positive association between total and unsaturated fat intake and breast cancer risk.

A prospective study of association of monounsaturated fat and other types of fat with risk of breast cancer.

BACKGROUND: Animal studies suggest that monounsaturated and polyunsaturated fat may have opposite effects on the risk of breast cancer. METHODS: We performed a population-based prospective cohort study, including 61,471 women aged 40 to 76 years from 2 counties in central Sweden who did not have any previous diagnosis of cancer; 674 cases of invasive breast cancer occurred during an average follow-up of 4.2 years. All subjects answered a validated 67-item food frequency questionnaire at baseline. Cox proportional hazards models were used to obtain adjusted rate ratio (RR) estimates with 95% confidence intervals (CIs). RESULTS: After mutual adjustment of different types of fat, an inverse association with monounsaturated fat and a positive association with polyunsaturated fat were found. The RR for each 10-g increment in daily intake of monounsaturated fat was 0.45 (95% CI, 0.22-0.95), whereas the RR for a 5-g increment of polyunsaturated fat was 1.69 (95% CI, 1.02-2.78); the increments correspond to approximately 2 SDs of intake in the population. Comparing the highest quartile of intake with the lowest, we found an RR of 0.8 (95% CI, 0.5-1.2) for monounsaturated fat and 1.2 (95% CI, 0.9-1.6) for polyunsaturated fat. Saturated fat was not associated with the risk of breast cancer. CONCLUSIONS: Our results indicate that various types of fat may have specific opposite effects on the risk of breast cancer that closely resemble the corresponding effects in experimental animals. Research investigations and health policy considerations should take into account the emerging evidence that monounsaturated fat might be protective for risk of breast cancer.

[Physico-chemical characteristics of different types of vegetable fats and oils used in the manufacture of candies]. / Características físico-químicas de diferentes tipos de grasas y aceites vegetales utilizados en la elaboración de bombones.

The quality of three vegetable fats (cocoa butter and two commercial fats) and three roasted nut oils (almond, hazelnut and peanut) used as raw material in the chocolate products manufacturing was studied. The hydroperoxide content, oxidative stability and fatty acid composition were determined and its health repercussion by atherogenicity and thrombogenicity indexes. Two commercial fats and cocoa butter showed higher oxidative stability, atherogenic and thrombogenic properties than oils because of its different fatty acid profiles. Peroxide value was a low reliability parameter of raw material shelf live. Rancimat presented a good correlation with the unsaturation index of different fats and oils, it was a better index than peroxide value. In the chocolate products manufacturing it would be advisable a good raw material selection and formulation in order to get a balance between technological properties, organoleptic qualities and the influence on the health. Those raw material with less primary oxidation and higher oxidative stability were also those of higher atherogenicity and thrombogenicity indexes.

A fish oil diet inhibits colon cancer in mice.

High-fat, high-cholesterol diets have been linked to colon cancer in both epidemiological and animal studies. Saturated and N-6 polyunsaturated fats have both been implicated as playing causative roles. Epidemiological studies have shown a reduced colon cancer incidence in populations consuming a large quantity of N-3 polyunsaturated fat. This study asked whether N-3 polyunsaturated fat found in fish oil would also be associated with reduced colon cancer in animal studies. 1,2-Dimethylhydrazine was used to induce colon cancer in mice fed three high-fat, high-cholesterol diets (beef tallow, safflower oil, and fish oil) and one low-fat, cholesterol-free diet (soybean oil). Colon adenocarcinomas developed in 55% of mice fed tallow, 48% of those fed low-fat diets, 33% of those fed safflower oil, and 18% of those fed fish oil (p less than 0.05). Tumors per animal were also greatest in mice fed tallow and fewest in those fed fish oil (p less than 0.05). Plasma cholesterol levels were significantly higher in mice fed tallow than in mice fed fish oil, but this did not show any association with tumors. Plasma triglyceride levels were not significantly different among groups but were strongly correlated with colon cancers (r = 0.90, p less than 0.025). In both plasma and colon mucosa cells, saturated fat levels were similar. Monounsaturated fat was highest in plasma of mice fed tallow and correlated strongly with colon cancers (r = 0.84, p less than 0.005). N-6 polyunsaturated fat was highest in plasma and colon mucosa cells of both mice fed safflower oil and those fed low-fat (soybean oil) diet, but there was no association with tumors. N-3 polyunsaturated fat was highest in plasma and colon mucosa cells of mice fed fish oil and showed a negative association with tumors (r = -0.57, p less than 0.05). Thus, in this model of colon cancer, a diet high in fish oil was associated with less colon cancer. Monounsaturated fat was most strongly correlated with tumors. This study suggests monounsaturated fat promotes colon tumors and N-3 polyunsaturated fat inhibits colon tumors.

Melanoma and dietary lipids.

Samples of subcutaneous adipose tissue were taken from 100 melanoma patients and 100 matched controls in Sydney in 1984-1985 and were analyzed for constituent fatty acids. The mean percentage of linoleic acid in the triglycerides of the subcutaneous adipose tissue (PLASAT) of these subjects was substantially higher than that in a similar group examined in 1975-1976. In addition, the percentage of polyunsaturated fatty acids was found to be higher in the melanoma patients than in the controls (p less than 0.01), and there were significantly more controls than patients who had a low PLASAT (p less than 0.01). Relevant literature is quoted and the suggestion is made that increased consumption of dietary polyunsaturates may have a contributory effect in the etiology of melanoma.

Fat and cancer.

Experimental studies and epidemiologic data both indicate that high-fat diets increase the risk of cancer at sites such as breast, colon, and pancreas. Dietary polyunsaturated vegetable oils promote tumorigenesis in animals whereas saturated fats and polyunsaturated fish oils either have little effect or are inhibitory. A blend of fats typical of the American diet enhanced mammary tumorigenesis effectively when fed as 40% of calories. After 9 to 10 weeks on this diet, reducing the fat to 10% of calories inhibited subsequent tumor development. Although dietary fat appears to act as a promoter, the exact mechanisms are still unknown. Cancer mortality in humans correlates better with total dietary fat than with degree of unsaturation, perhaps because most diets contain more than the amount of polyunsaturated fatty acids required for maximum effect on tumorigenesis in animals. A reduction in total dietary fat is recommended to reduce the current high cancer mortality.