Dietary Fat Quality Research Articles

Differential Effects of Dietary Fatty Acids on Body Composition and Adiposity

Recent evidence has highlighted that fat accumulation, particularly abdominal fat distribution, is strongly associated with metabolic disturbance. It is also well-recognized that the metabolic responses to variations in macronutrients intake can affect body composition. Previous studies suggest that the quality of dietary fats can be considered as the main determinant of body-fat deposition, fat distribution, and body composition without altering the total body weight; however, the effects of dietary fats on body composition have controversial results. There is substantial evidence to suggest that saturated fatty acids are more obesogen than unsaturated fatty acids, and with the exception of some isomers like conjugate linoleic acid, most dietary trans fatty acids are adiposity enhancers, but there is no consensus on it yet. On the other hand, there is little evidence to indicate that higher intake of the n-3 and the n-6 polyunsaturated fatty acids can be beneficial in attenuating adiposity, and the effect of monounsaturated fatty acids on body composition is contradictory. Accordingly, the content of this review summarizes the current body of knowledge on the potential effects of the different types of dietary fatty acids on body composition and adiposity. It also refers to the putative mechanisms underlying this association and reflects on the controversy of this topic.

The Role of Vegan Diets in Lipotoxicity-induced Beta-cell Dysfunction in Type-2-Diabetes: A Narrative Review.

Type-2-diabetes is considered the new plague of the current century and its incidence and prevalence are rapidly increasing. Chronic insulin resistance and a progressive decline in beta-cell function are discussed as the root causes of type-2-diabetes. Both are associated with obesity and prolonged exposure to pathologically elevated concentrations of circulating free fatty acid (FFA) levels in the blood. Fatty acid derivatives may interfere with beta-cell function and ultimately lead to their death through lipoapoptosis. The harmful effects of chronically elevated FFA levels on glucose homeostasis and non-adipose tissues are generally referred to as lipotoxicity. Pancreatic beta-cells appear to be particularly vulnerable, and both dietary fat quantity and quality may impact their function. Diets high in saturated fat are especially harmful to beta-cells while (poly-)unsaturated fatty acids (PUFA) are associated with beta-cell protective effects. Therefore, this narrative review suggests that a dietary modification toward a low-fat vegan diet might help to prevent or reduce lipotoxicity-induced beta-cell dysfunction. By cutting the oversupply of saturated fat and reducing total calorie intake, and by improving both body weight and glycemic control, low-fat vegan diets may reduce the likelihood of lipotoxic events to occur. In light of the accumulating evidence that lipotoxic events are tightly coupled to excess glucose levels, improved glycemic parameters appear to be of utmost importance. These mechanisms are likely to contribute complementarily to improved beta-cell function in individuals with type-2-diabetes who choose a low-fat vegan diet. Physicians must consider these findings when counseling patients on lifestyle modifications and healthy nutrition.

Dietary Fat Quality and Pre-diabetes: A Case-control Study.

Background:The relationship between dietary fat quality (DFQ) indices and pre-diabetes has not been well studied. This study aimed to determine the association of DFQ indices and fatty acid intake with pre-diabetes.Methods:This case-control study included 150 subjects with normal fasting blood glucose (FBG) and 147 pre-diabetic subjects. Dietary intake was assessed by a validated food-frequency questionnaire. DFQ indices including atherogenicity (AI) and thrombogenicity (TI), the ratios of hypo- and hypercholesterolemic (h:H), polyunsaturated:saturated (P:S) and n-3:n-6 polyunsaturated fatty acids were calculated. FBG test and 2-hour oral glucose tolerance test (OGTT) were measured.Results:After adjustment for some confounding variables, a positive association was found between intake of total saturated fatty acids (SFA), myristic acid, palmitic acid, and pre-diabetes, and a negative association was observed among n-3 polyunsaturated fatty acids, eicosapentaenoic, docosahexaenoic and arachidonic acids intake and pre-diabetes. AI was found to be positively associated with pre-diabetes (OR 6.68, 95% CI 2.57-17.34). An inverse relationship was observed between n-3:n-6 (OR 0.37, 95% CI 0.14-0.93) and h:H (OR 0.20, 95% CI 0.07-0.52) ratios with pre-diabetes.Conclusions:Higher intake of dietary n-3 fatty acids was adversely, whereas SFA intake was positively related to pre-diabetes morbidity. DFQ indices may be a useful measure to investigate fat intakes and blood glucose disturbances.

Nutritional programming in early life: the role of dietary lipid quality for future health

Worldwide, overweight and obesity have increased dramatically, not only in high income countries. Clearly, unhealthy diets and sedentary lifestyle are important drivers of the increased obesity rates, but increasing evidence indicates that the vulnerability for later life non-communicable diseases is set during the first 1000 days, the period from conception until 2 years of age. The growth during this period is faster than during any other period in life. Dietary fats provide energy for growth, but also supply essential fatty acid (FA) precursors for long chain polyunsaturated FA that are building blocks and signals for adipose tissue development. Both epidemiological and experimental data support the notion that specific improvements in dietary fat quality,e.g.specific changes in the fatty acid composition as well as the structural organization of dietary lipids, may reduce the risk of obesity and other adverse outcomes in later life, but clinical evidence is limited and largely inconclusive. We anticipate that effects of such relatively small improvements in nutrient quality may be difficult to measure on the short term and have limited impact in healthy children. However, for children that already experience challenging conditions in the womb and have a higher risk profile based on deviations in birthweight and postnatal growth, the potential protective effects of improved dietary lipid quality in early life could be more substantial. Results from randomized clinical studies testing improved lipid quality concepts will help to develop specific strategies to adapt infant nutrition based on the need with the aim to improve long term outcomes.

Dietary Fat Quality in Normolipidic Diets Affects Hepatocyte’s Nuclear Phenotypes

Dietary fat quality affects overall systemic parameters and produce hepatic accumulation of fat and inflammation (steatohepatitis). In this communication we have assessed how mouse liver nuclear phenotypes are influenced by diets containing 7% lipid prepared with lard, linseed oil or soybean oil for 32 weeks. Liver specimens were imprinted on glass slides, fixed and stained with DAPI. 3D confocal images were obtained and employed for the calculation of nuclear thickness, nuclear volume and DAPI-DNA intensity. Hepatocytes’ nuclei could be classified as diploid A, diploid B, tetraploid and higher ploidy levels. Linseed oil in the diet resulted in increased frequency of diploid A (more compact) and less polyploidy, while lard caused increased volume and more polyploidy. Soybean oil produced intermediate nuclear sizes. The results suggest a high demand on liver physiology promoted by lard, which has a predominance of saturated fatty acids, while linseed oil promoted the opposite effect.

The effects of brain-friendly diet on cognitive performance (Brave study)

AbstractIntroduction:Cognitive performance is related to lipid and glucose metabolism and metabolic activation that are regulated by diet. The Brave study has shown beneficial effects of brain-friendly diet (Brainfood) on metabolic health in office workers with elevated metabolic risk. We further examined the effects of Brainfood on cognitive performance.Materials and methods:We conducted a diet-switch, 4-week intervention study on 84 volunteers with elevated plasma LDL levels in pre-screening. During the control period participants continued their habitual eating pattern and were offered an optional lunch following western-type diet, and they did not receive nutritional guidance. In Brainfood period, lunch, snack and breakfast offering was optimised for the quality of carbohydrates and fat and the intake of salt and protein. Educated nutritionist instructed the participants to follow the Brainfood diet and regular meal pattern.Participants kept a 3-day food record at the end of control and Brainfood periods. For each participant, we calculated the Brainfood ratio comparing the total frequencies of consumption of brain-friendly and brain-unfriendly foods. We ranked the subjects also according to the change in brain-friendly nutrient intake (saturated fat, polyunsaturated fat, fibre, sugar and salt) from control to Brainfood period.Cognitive performance (cognitive control and flexibility, attention, inhibition, learning, and memory) were measured with a combination of traditional standardized neuropsychological tests (Bourdon-Wiersma double task, Stroop Colour and Word Test, WMS-III: Letter-Number Sequencing, Rey Auditory Verbal Learning Test) and modern computer and mobile tests (Flexible Attention Test FAT, N-Back task and Task-switching task) before and after the Brainfood diet. In addition, participants evaluated their vigilance, task load and performance after each test with the Karolinska Sleepiness Scale (KSS) and NASA Task Load Index (NASA-TLX).We compared the change in cognitive performance before and after Brainfood diet between the subgroups with the highest and lowest Brainfood ratio and the highest and lowest brain-friendly nutrient intake using repeated measures analysis of variance.Results:Brainfood diet reduced intakes of saturated fat and salt, and increased intakes of polyunsaturated fat, fibre, vitamin C and D, iron and magnesium (p < 0,03). Participants with the highest Brainfood ratio improved reaction time (FAT; p-value for interaction 0,01, multiple comparison correction not applied), switch cost (Task-switching; p = 0,02) and inhibition tendency (Stroop; p = 0,047). Better dietary fat quality decreased self-reported physical strain (NASA-TLX; p-values < 0,007), and higher fibre intake decreased self-reported sleepiness (KSS; p = 0,033).Discussion:Brainfood diet may positively affect cognitive performance in office workers with elevated metabolic risk.

Colonic bacterial composition is sex-specific in aged CD-1 mice fed diets varying in fat quality.

Evidence suggests that sex influences the effect of diet on the gut bacterial composition, yet, no studies have been performed assessing dietary fatty acid composition (i.e., fat quality) in this context. This study examined the effect of dietary fat quality on colonic bacterial composition in an aged, genetically-diverse mouse population. CD-1 mice were fed isoenergetic diets consisting of (1) control fat (CO; “Western-style” fat blend), (2) CO supplemented with 30% fish oil, (3) CO supplemented with 30% dairy fat, or (4) CO supplemented with 30% echium oil. Fecal samples were collected at mid-life and aged (reproductively senescent) time points. Overall, the abundance of Bacteroidetes was greater in mice fed echium oil compared to mice fed the control fat. Examination of colonic bacterial relative abundance also revealed sex differences, with 73 bacterial taxa being differentially expressed in males and females. Notably, results showed a strong interactive effect among the diet, sex, and age of mice which influenced colonic bacterial relative abundance and alpha diversity. In males, supplementation of the diet with dairy fat or echium oil caused the abundance of Bacteroidetes and Bacteroides to change with age. Additionally, supplementation of the diet with fish oil induced sex-dependent changes in the alpha diversity of aged mice compared to mid-life. This work supports that sex is a critical factor in colonic bacterial composition of an aged, genetically-heterogenous population. Moreover, this study establishes that the effectiveness of dietary interventions for health maintenance and disease prevention via direct or indirect manipulation of the gut microbiota is likely dependent on an individual’s sex, age, and genetic background.

A modelling approach to investigate the impact of consumption of three different beef compositions on human dietary fat intakes.

To apply a dietary modelling approach to investigate the impact of substituting beef intakes with three types of alternative fatty acid (FA) composition of beef on population dietary fat intakes. Cross-sectional, national food consumption survey - the National Adult Nutrition Survey (NANS). The fat content of the beef-containing food codes (n 52) and recipes (n 99) were updated with FA composition data from beef from animals receiving one of three ruminant dietary interventions: grass-fed (GRASS), grass finished on grass silage and concentrates (GSC) or concentrate-fed (CONC). Mean daily fat intakes, adherence to dietary guidelines and the impact of altering beef FA composition on dietary fat sources were characterised. Ireland. Beef consumers (n 1044) aged 18-90 years. Grass-based feeding practices improved dietary intakes of a number of individual FA, wherein myristic acid (C14 : 0) and palmiticacid (C16 : 0) were decreased, with an increase in conjugated linoleic acid (C18 : 2c9,t11) and trans-vaccenic acid (C18 : 1t11; P < 0·05). Improved adherence with dietary recommendations for total fat (98·5 %), SFA (57·4 %) and PUFA (98·8 %) was observed in the grass-fed beef scenario (P < 0·001). Trans-fat intakes were increased significantly in the grass-fed beef scenario (P < 0·001). To the best of our knowledge, the present study is the first to characterise the impact of grass-fed beef consumption at population level. The study suggests that habitual consumption of grass-fed beef may have potential as a public health strategy to improve dietary fat quality.

High-fat diets provoke phosphorus absorption from the small intestine in rats.

The ratio of dietary carbohydrate to fat may affect phosphorus metabolism because both calcium and phosphorus are regulated by similar metabolic mechanisms, and a high-fat diet (HFD) induces deleterious effects on the absorption of dietary calcium. We hypothesized that an HFD induces an increase in phosphorus absorption. The aim of this study was to evaluate the effects of differences in the quantity and quality of dietary fat on phosphorus metabolism over the short- and long-term. Eighteen 8-wk-old Sprague-Dawley male rats were fed an isocaloric diet containing varied ratios of carbohydrates to fat energy and sources of fat (control diet, HFD, and high- saturated fat diet [HF-SFA]). At 3 d and 7 wk after the allocation and initiation of the test diets, feces and urine were collected and used for phosphorus and calcium measurement. The fecal phosphorous concentration (F-Pi) was lower in the HF-SFA group than in the other two groups; however, the urine phosphorus concentration (U-Pi) was significantly higher in the HF-SFA group than the other two groups when the rats were fed over the short- (P < 0.01) and long -term (P < 0.01 versus control, P < 0.05 versus HFD group). There were no significant differences in type-IIa sodium-phosphate cotransporter (NaPi-2 a) and type-IIc sodium-phosphate cotransporter (NaPi-2 c) mRNA expression, which are renal phosphate transport-related genes; however, the expression of type-IIb sodium-phosphate cotransporter (NaPi-2 b) and type-III sodium-phosphate cotransporter (Pit-1) mRNA in the duodenum was higher in the HFD and HF-SFA groups than in the control group (P < 0.05), although there were no significant differences in these in the jejunum. The present results indicated that an HFD, particularly HF-SFA, increases intestinal phosphate absorption compared with control.

Long-Chain Polyunsaturated Fatty Acids Are Associated with Blood Pressure and Hypertension over 10-Years in Black South African Adults Undergoing Nutritional Transition

Nutritional transition in Africa is linked with increased blood pressure (BP). We examined 10-year fatty acid status and longitudinal associations between individual long-chain polyunsaturated fatty acids (PUFA), BP and status of hypertension (≥140/90 mmHg and/or medication use) in black South Africans. We included 300 adults (>30 years) participating in the Prospective Urban Rural Epidemiology study, and analysed data from three consecutive examinations (2005, 2010 and 2015 study years). Fatty acids in plasma phospholipids were analysed by gas chromatography-mass spectrometry. We applied sequential linear mixed models for continuous outcomes and generalized mixed models for the hypertension outcome, in the complete sample and separately in urban and rural subjects. Mean baseline systolic/diastolic BP was 137/89 mmHg. Ten-year hypertension status increased among rural (48.6% to 68.6%, p = 0.001) and tended to decrease among urban subjects (67.5% to 61.9%, p = 0.253). Regardless of urbanisation, n-6 PUFA increased and eicosapentaenoic acid (EPA, C20:5 n-3) decreased over the 10-years. Subjects in the highest tertile of arachidonic acid (C20:4 n-6) had 3.81 mmHg lower systolic (95% confidence interval (CI): −7.07, −0.54) and 3.82 mmHg lower diastolic BP (DBP) (95% CI: −5.70, −1.95) compared to the reference tertile, irrespective of lifestyle and clinical confounders. Similarly, osbond acid (C22:5 n-6) was inversely associated with DBP. Over the 10-years, subjects in the highest EPA tertile presented with +2.92 and +1.94 mmHg higher SBP and DBP, respectively, and with 1.46 higher odds of being hypertensive. In black South African adults, individual plasma n-6 PUFA were inversely associated with BP, whereas EPA was adversely associated with hypertension, supporting implementation of dietary fat quality in national cardiovascular primary prevention strategies.

Quality of dietary fat and genetic risk of type 2 diabetes: individual participant data meta-analysis

Quality of dietary fat and genetic risk of type 2 diabetes: individual participant data meta-analysis

Association between carbohydrate intake and fatty acids in the de novo lipogenic pathway in serum phospholipids and adipose tissue in a population of Swedish men

PurposeFatty acid composition in blood and adipose tissue (AT) is a useful biomarker of dietary fat quality. However, circulating saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) have been proposed to also reflect carbohydrate-induced de novo lipogenesis (DNL) and stearoyl-CoA desaturase (SCD) activity. We aimed to test the hypothesis that high carbohydrate intake is related to SFA and MUFA in serum or AT in a Swedish population.MethodsFatty acid composition was measured in serum phospholipids (PL) and AT by gas chromatography in 63-year-old men (n = 299). Carbohydrate and alcohol intake was assessed (validated 7-day food records) in relation to total SFA, 16:0 (palmitate), 16:1 (palmitoleate), and estimated SCD activity (16:1n-7/16:0-ratio) in serum PL and in AT, respectively.ResultsTotal carbohydrate intake was inversely associated with 16:0 in PL (P = 0.005), independently of BMI. Disaccharides were non-linearly (restricted cubic splines) and weakly associated with 16:1 and SCD activity in PL (nonlinear trend, P ≤ 0.02) but not AT. Carbohydrate intake and SCD expression were not associated (P ≥ 0.08, n = 81). Alcohol intake was, however, linearly associated with 16:0 in PL (P < 0.001), and with 16:1 (P < 0.001) and SCD activity (P ≤ 0.005) in both PL and AT.ConclusionsHigher carbohydrate intake from sugar-rich foods or beverages was not clearly reflected by higher SFA or SCD activity in serum PL or AT. Alcohol was, however, associated with higher SFA and MUFA.

Quality of dietary fat and genetic risk of type 2 diabetes: individual participant data meta-analysis

ObjectiveTo investigate whether the genetic burden of type 2 diabetes modifies the association between the quality of dietary fat and the incidence of type 2 diabetes.DesignIndividual participant data meta-analysis.Data sourcesEligible...

Dietary fats and mortality among patients with type 2 diabetes: analysis in two population based cohort studies

ObjectiveTo assess the association of dietary fatty acids with cardiovascular disease mortality and total mortality among patients with type 2 diabetes.DesignProspective, longitudinal cohort study.SettingHealth professionals in the United States.Participants11 264...

Total and Subtypes of Dietary Fat Intake and Its Association with Components of the Metabolic Syndrome in a Mediterranean Population at High Cardiovascular Risk.

Background: The effect of dietary fat intake on the metabolic syndrome (MetS) and in turn on cardiovascular disease (CVD) remains unclear in individuals at high CVD risk. Objective: To assess the association between fat intake and MetS components in an adult Mediterranean population at high CVD risk. Design: Baseline assessment of nutritional adequacy in participants (n = 6560, men and women, 55–75 years old, with overweight/obesity and MetS) in the PREvención con DIeta MEDiterránea (PREDIMED)-Plus randomized trial. Methods: Assessment of fat intake (total fat, monounsatured fatty acids: MUFA, polyunsaturated fatty acids: PUFA, saturated fatty acids: SFA, trans-fatty acids: trans-FA, linoleic acid, α-linolenic acid, and ω-3 FA) using a validated food frequency questionnaire, and diet quality using 17-item Mediterranean dietary questionnaire and fat quality index (FQI). Results: Participants in the highest quintile of total dietary fat intake showed lower intake of energy, carbohydrates, protein and fiber, but higher intake of PUFA, MUFA, SFA, TFA, LA, ALA and ω-3 FA. Differences in MetS components were found according to fat intake. Odds (5th vs. 1st quintile): hyperglycemia: 1.3–1.6 times higher for total fat, MUFA, SFA and ω-3 FA intake; low high-density lipoprotein cholesterol (HDL-c): 1.2 higher for LA; hypertriglyceridemia: 0.7 lower for SFA and ω-3 FA intake. Conclusions: Dietary fats played different role on MetS components of high CVD risk patients. Dietary fat intake was associated with higher risk of hyperglycemia.

Incorporation of Unique, Diet-derived Fatty Acids into Hepatic Tissue Is Associated with Improved Glucose Homeostasis in Aged CD-1 Mice (OR24-02-19)

ObjectivesWe hypothesized that the chronic consumption of unique dietary FA derived from dairy fat and echium oil, respectively, would affect the FA composition and content of the hepatic tissue and correlate with parameters of glucose homeostasis in an aged, genetically heterogeneous mouse population. Our objectives were to i) measure glucose homeostasis, ii) determine the FA composition of hepatic tissue, and iii) correlate physiologic data and hepatic FA content by diet and sex. MethodsFrom one month of age, CD-1 male and female mice (n = 10/diet/sex) were fed either a high-fat (40% total energy) control diet comprising of the FA composition of the typical U.S. American diet (CO), or an isoenergetic diet with 30% of CO fat replaced with dairy fat (BO) or echium oil (EO) for the study duration of 13 months. Every three months, whole-body glucose homeostasis was assessed (i.e., glucose tolerance and insulin tolerance tests (GTT and ITT, respectively)). At the end of the study, hepatic tissue was collected and analyzed for FA composition via gas-liquid chromatography. ResultsHepatic content of stearidonic acid (SDA; 18:4 n-3) and γ-linolenic acid (18:3 n-6) was greatest in EO-fed mice (P < .0001). Mice fed a BO-diet had the greatest hepatic content of total odd- and branched-chain FA (OBCFA) and conjugated linoleic acids (P < .0001), as well as a greater hepatic content of 18:1 isomers compared to EO-fed mice (P < .001). In EO-fed females, hepatic content of SDA correlated with improved glucose tolerance, as determined by GTT area under the curve (r = –.94; P < 0.01), and in EO-fed males, hepatic content of SDA was positively associated with improved insulin sensitivity (r = .79; P < 0.05). In BO-fed males, hepatic content of total OCFA was negatively correlated with fasting plasma insulin levels (r = –.83; P < 0.05), and hepatic content of total iso BCFA was associated with improved insulin sensitivity (r = –.89; P < 0.05). ConclusionsThese findings demonstrate that habitual consumption of unique FA derived from dairy fat and echium oil influences hepatic FA composition and content and correlates with improvements in whole-body glucose homeostasis in an aged population. Furthermore, this study suggests that dietary fat quality may be part of an effective preventative strategy for metabolic diseases such as T2D in the elderly. Funding SourcesArmin Grams Memorial Research Award, UVM Robert Larner, M.D. College of Medicine; USDA-NIFA Hatch Fund (accession number: 1006628).

Using metabolic profiling and gene expression analyses to explore molecular effects of replacing saturated fat with polyunsaturated fat—a randomized controlled dietary intervention study

ABSTRACTBackgroundReplacing dietary saturated fatty acids (SFAs) with polyunsaturated fatty acids (PUFA) reduces the plasma low-density lipoprotein (LDL) cholesterol and subsequently the risk of cardiovascular disease. However, beyond changes in LDL cholesterol, we lack a complete understanding of the physiologic alterations that occur when improving dietary fat quality.ObjectivesThe aim of this study was to gain knowledge of metabolic alterations paralleling improvements in the fat quality of the diet.MethodsWe recently conducted an 8-wk, double-blind, randomized controlled trial replacing SFAs with PUFAs in healthy subjects with moderate hypercholesterolemia (n = 99). In the present substudy, we performed comprehensive metabolic profiling with multiple platforms (both nuclear magnetic resonance- and mass spectrometry-based technology) (n = 99), and analyzed peripheral blood mononuclear cell gene expression (n = 95) by quantitative real-time polymerase chain reaction.ResultsA large number of lipoprotein subclasses, myristoylcarnitine and palmitoylcarnitine, and kynurenine were reduced when SFAs were replaced with PUFAs. In contrast, bile acids, proprotein convertase subtilisin/kexin type 9, acetate, and acetoacetate were increased by the intervention. Some amino acids were also altered by the intervention. The mRNA levels of LXRA and LDLR were increased, in addition to several liver X receptor α target genes and genes involved in inflammation, whereas the mRNA levels of UCP2 and PPARD were decreased in peripheral blood mononuclear cells after replacing SFAs with PUFAs. Partial least squares-discriminant analysis showed that the 30 most important variables that contributed to class separation spanned all classes of biomarkers, and was in accordance with the univariate analysis.ConclusionsApplying metabolomics in randomized controlled dietary intervention trials has the potential to extend our knowledge of the biological and molecular effects of dietary fat quality. This study was registered at clinicaltrials.gov as NCT 01679496.

Association of Colonic Bacterial Composition with Host Physiology is Dependent on Dietary Fat Quality and Sex in Aging CD‐1 Mice

Colonic bacterial composition is critical in the development of metabolic diseases, yet, the significance of specific bacterial taxa in disease risk, pathogenesis, and prevention is not well defined. While it is known that diet, sex, age, and genetic makeup of the host can influence colonic bacterial composition, how these factors interact with the bacteria to affect host physiology is poorly understood. Our study utilized the genetically heterogeneous CD‐1 mouse stock to determine the effect of long‐term dietary fat quality (i.e., fatty acid composition) and sex on colonic bacterial composition (relative abundance and diversity) during aging. For 13 months, starting at the age of four weeks, male and female mice were fed one of four isoenergetic (40% total energy) diets: i) Control, U.S. fat blend (CO; representing the dietary fat quality of the average U.S. American); ii) CO fat blend displaced with 30% fish oil (FO); iii) CO fat blend displaced with 30% dairy (butter) fat (BO); and iv) CO fat blend displaced with 30% echium oil (EO). Feed intake and body weight were measured weekly and monthly, respectively. Glucose and insulin tolerance tests (GTT and ITT, respectively) were performed every three months to assess glucose homeostasis and insulin resistance. Individual fecal samples were collected via metabolic cages at 10.5 months of age (i.e., mid‐life in life course) and 13.5 months of age (i.e., aged period in life course; post‐reproductive senescence). Multivariate Spearman correlations were used to determine associations between colonic bacterial composition and glucose homeostasis and insulin resistance. At mid‐life, relative abundance of Alistipes was positively correlated with weight gain in FO‐fed (r = 0.83; P &lt; 0.05) and BO‐fed (r = 0.76; P &lt; 0.05) mice, whereas the relative abundance of Parabacteroides was positively correlated with weight gain in EO‐fed mice (r = 0.68; P &lt; 0.05). In aged mice, the abundance of Allobaculum and Anaerostipes was associated with improved glucose tolerance in BO‐fed mice, as determined by a reduction in GTT area under the curve (AUC; r = −0.65 and r = −0.58, respectively; P &lt; 0.05). In addition, alpha diversity (Chao1) was associated with improved glucose tolerance (via GTT AUC) in aged EO‐fed mice (r = −0.74; P &lt; 0.05). In females, a negative correlation was found between the relative abundance of Roseburia and Barnesiella and fasting plasma glucose at mid‐life (r = −0.51; P &lt; 0.05) and aged (r = −0.58; P &lt; 0.01) life stages, respectively, indicating that these bacterial taxa may contribute positively to glucose homeostasis. Yet, only in aged males, the abundance of Lactobacillus was correlated with improved fasting plasma glucose (r = −0.65; P &lt; 0.01). Our study suggests that dietary fat quality and sex modulate the association of specific colonic bacterial taxa and metabolic risk factors in CD‐1 mice, and that the effects of certain colonic bacteria on host physiology may change with age of an individual.Support or Funding InformationArmin Grams Memorial Research Award, UVM Robert Larner, M.D. College of Medicine; USDA‐NIFA Hatch Fund (accession number: 1006628).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Abstract P287: Hypocholesterolemic Effect of Dietary Stearic Acid May Be Partly Mediated via Alterations in Fecal Bile Acid Metabolism

Introduction: Dietary fat quality has a significant impact on CVD risk. Among the saturated fatty acids (FA), we and others have documented that stearic (18:0) is unique because, unlike shorter chain FA (12:0, 14:0, 16:0), it does not raise plasma LDL-C levels, relative to monounsaturated FA, such as oleic acid (18:1). The mechanism(s) responsible for this effect are not fully elucidated. Hypothesis: We tested the hypothesis that the hypocholesterolemic effect of dietary 18:0 and 18:1 relative to 16:0 is mediated by alterations in fecal bile acid metabolism. Methods: Primary (cholic, chenodeoxycholic) and secondary bile acids (SBA: lithocholic [LA], deoxycholic [DCA]) were quantified in stool samples from a randomized controlled cross-over trial examining the effect of dietary FA on CVD risk factors. Subjects (N=20 postmenopausal women, 50-85 years, BMI 25-35kg/m 2 , LDL-C &gt;100mg/dL) consumed each diet for 35 days separated by a 2 week washout period. Diets provided 55%E carbohydrate, 15%E protein and 30%E fat with half of the fat provided by 16:0, 18:0 or 18:1, respectively. CVD risk factors (lipids, glucose, insulin, inflammatory markers) were measured using standard methodology. For fecal bile acids analysis, freeze dried samples were spiked with the corresponding deuterated internal standards, followed by an overnight extraction, purification and analysis using reversed-phase liquid chromatography coupled with electrospray ionization quadrupole time of flight mass spectrometry. Quantification was by isotopic dilution. Spearman correlation coefficients were calculated between bile acids and CVD risk factors. Results: Fecal total SBA levels were significantly lower after subjects consumed the 18:0 (4.5±3.9 umol/g) compared to the 18:1 (6.8±5.7 umol/g) diet, with intermediate levels after the 16:0 diet (5.2±3.6 umol/g). This was predominantly due to significantly lower LA, and to a lesser extent DCA levels. No detectable differences were observed in primary bile acids levels. Total, LA and DCA levels were positively correlated with insulin (r=0.38 to 0.45; p&lt;0.05), hsCRP (r=0.31 to 0.37, p&lt;0.02), TG (r=0.46 to 0.60; p&lt;0.001), VLDL-C (r=0.47 to 0.63; p&lt;0.001), TC/LDL-C (r=0.42 to 0.63; p&lt;0.001) and LDL-C/HDL-C (0.37 to 0.57; p&lt;0.001) ratios, and negatively with HDL-C (r= -0.51 to -0.44; p&lt;0.001) levels. LA levels were also positively correlated with LDL-C levels (r=0.33; p=0.011). Conclusion: These data suggest that the hypocholesterolemic effect of dietary 18:0 was not mediated by increased bile acid excretion as was observed with dietary 18:1. Instead, dietary 18:0 appears to have an inhibitory effect on hydrophobic SBA synthesis in the intestine, which in turn could reduce the efficiency of cholesterol solubilization and thus cholesterol absorption. Further studies on the effects of dietary 18:0 on gut microbiome populations involved in SBA synthesis are warranted.

Higher intake of dietary n-3 PUFA and lower MUFA are associated with fewer menopausal symptoms

Objective: This study aimed to investigate the association between dietary fat quality and menopausal symptoms.Methods: We carried out a cross-sectional study with 393 Iranian postmenopausal women. Dietary intakes and menopausal symptoms were assessed, using a validated food frequency questionnaire and a menopausal rating scale (MRS) questionnaire, respectively. Participants were divided into low and high total MRS and its domain scores.Results: Women in the highest quartiles of monounsaturated fatty acids (MUFA) had higher somatic symptoms compared with women in the lowest quartile (odds ratio [OR] 3.41; 95% confidence interval [CI] 1.17–9.95). Women in the highest quartiles of n-3 polyunsaturated fatty acids (PUFA) (OR 0.58; 95% CI 0.32–1.05), eicosapentaenoic acid (EPA) (OR 0.66; 95% CI 0.37–1.20), and n-3:n-6 PUFA ratio (OR 0.49; 95% CI 0.25–0.97) had lower somatic symptoms compared to the lowest quartiles. The OR for psychological symptoms decreased from the lowest to the highest quartiles of n-3 PUFA (OR 0.47; 95% CI 0.20–1.11) and n-3:n-6 PUFA ratio (OR 0.46; 95% CI 0.24–0.86). Higher intakes of EPA (OR 0.53; 95% CI 0.29–0.99) and docosahexaenoic acid (OR 0.51; 95% CI 0.27–0.95) were found to be related with fewer urogenital symptoms.Conclusion: Consuming diets low in MUFA intake, but high in n-3 PUFA, and with a more favorable ratio of n-3:n-6 PUFA may be helpful for improving menopausal symptoms.