Eight weeks of daily cottonseed oil intake attenuates postprandial angiopoietin-like proteins 3 and 4 responses compared to olive oil in adults with hypercholesterolemia: A secondary analysis of a randomized clinical trial.

Angiopoietin-like proteins (ANGPTLs) -3, -4, and -8 are regulators of lipid metabolism and have been shown to respond to changes in dietary fats. It is unknown how ANGPTLs respond to cottonseed oil (CSO) and olive oil (OO) consumption in a population with hypercholesterolemia. The purpose of this study was to determine the impact of CSO vs. OO consumption on fasting and postprandial ANGPTL responses in adults with hypercholesterolemia. We hypothesized that CSO would have lower fasting and postprandial ANGPTL responses compared with OO. Forty-two adults with high cholesterol completed a single-blind, randomized trial comparing CSO (n = 21) vs. OO (n = 21) diet enrichment. An 8-week partial outpatient feeding intervention provided ∼60% of the volunteers' total energy expenditure (∼30% of total energy expenditure as CSO or OO). The remaining 40% was not controlled. Fasting blood draws were taken at pre-, mid-, and postintervention visits. Volunteers consumed a high saturated fat meal followed by 5 hours of blood draws pre- and postvisits. Fasting ANGPTL3 had a marginally significant treatment by visit interaction (P = .06) showing an increase from pre- to postintervention in CSO vs. OO (CSO: 385.1 ± 27.7 to 440.3 ± 33.9 ng/mL; OO: 468.2 ± 38.3 to 449.2 ± 49.5 ng/mL). Both postprandial ANGPTL3 (P = .02) and ANGPTL4 (P < .01) had treatment by visit interactions suggesting increases from pre- to postintervention in OO vs. CSO with no differences between groups in ANGPTL8. These data show a worsening (increase) of postprandial ANGPTLs after the OO, but not CSO, intervention. This aligns with previously reported data in which postprandial triglycerides were protected from increases compared with OO. ANGPTLs may mediate protective effects of CSO consumption on lipid control. This trial was registered at clinicaltrials.gov (NCT04397055).

A 4-Week Pecan-Enriched Diet Improves Postprandial Lipid Peroxidation in Aging Adults.

Pecans are rich in bioactive compounds known to reduce oxidative stress and provide glucoregulatory benefits. Few studies assessing the effect of a pecan-enriched diet on such health outcomes suggest potential improvements to cardiometabolic health; however, this has not been studied in an older adult population. Thus, we aimed to examine the effect of daily pecan consumption for 4-weeks on fasting and postmeal antioxidant status, oxidative stress, and markers of glycemia in healthy aging adults. In this randomized, parallel, controlled trial, 41 healthy adults (50-75 years) either consumed 68 g of pecans/day (pecan; n = 21) or avoided all nuts (control; n = 20). At pre- (V1) and postintervention visits (V2), blood samples were obtained at fasting, and 30, 60, and 120 min following a high saturated fat meal to assess changes in malondialdehyde, which is a measure of lipid peroxidation, total antioxidant capacity (TAC), glucose, and insulin. Across the intervention, there were no differences in fasting or postprandial TAC, glucose, or insulin for pecan versus control. There was a trend for a difference in fasting lipid peroxidation from V1 to V2 by treatment (P = .06) driven by a slight reduction for pecan versus control (Δpecan: -2.0 ± 1.1 vs. Δcontrol: +0.6 ± 0.8 µM). In addition, postprandial lipid peroxidation was suppressed at V2 for pecan, and this was different from control (pecan areas under the curve (AUC): 10.6 ± 1.3 µM/h to 9.1 ± 1.2 µM/h vs. control AUC: 8.9 ± 1.3 µM/h to 9.2 ± 1.1 µM/h; P = .03). These findings suggest that a 1 month, pecan-enriched diet is protective against postmeal oxidative stress. Longer interventions or a diabetic population may be needed to observe glucoregulatory benefits. Clinical Trial Registration: NCT04385537.

Metabolic responses to 8 weeks of consuming cottonseed oil versus olive oil in adults with dyslipidaemia: a randomised trial.

BACKGROUND: Differences in metabolic responses between diets rich in monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) could affect energy balance and weight maintenance. The present study was a secondary analysis to investigate 8-week diet interventions rich in either PUFA (cottonseed oil [CSO]) or MUFA (olive oil [OO]) on metabolic responses in adults with dyslipidaemia. METHODS: Forty-one adults with dyslipidaemia completed this randomised trial consisting of an 8-week partial-outpatient feeding trial. Provided foods accounted for about 60% of their daily energy needs, with about 30% of energy needs provided by CSO (n = 20) or OO (n = 21). At pre- and postdiet intervention visits, participants consumed a high saturated fatty acid (SFA) meal (35% daily energy needs, 47.9% from SFA), and fasting and 3.5-h postprandial indirect calorimetry were used to measure energy expenditure (EE) and substrate oxidation. RESULTS: No changes were observed in fasting measures. The OO group had greater increases in postprandial EE (p = 0.002); however, there were no differences in substrate oxidation between groups. A lack of metabolic flexibility was found in both groups, which was partially explained by changes in insulin sensitivity (homeostasis model assessment of insulin resistance). CONCLUSIONS: The results of the present study show that OO, but not CSO, diet enrichment improves EE after an occasional high SFA meal, which may improve weight maintenance over time. This study is registered at clinicaltrials.gov (NCT04397055).

Hunger and satiety responses to diets enriched with cottonseed oil vs. olive oil.

Studies suggest that the type of dietary fat consumed habitually may modulate appetite and further influence weight management. The purpose of this study was to evaluate the impact of an 8-week diet intervention enriched with either cottonseed oil (CSO; polyunsaturated fat-rich) or olive oil (OO; monounsaturated fat-rich) on appetite responses in adults with high cholesterol. This was a parallel design, randomized partial outpatient feeding trial designed to provide approximately 60% of participants daily energy needs with ∼30% of energy needs as CSO (n = 21, BMI 27.3 ± 0.92 kg/m2, age 53 ± 2y) or OO (n = 21, BMI 27.6 ± 1.20 kg/m2, age 54 ± 2y). A high saturated fat meal challenge was completed at pre- and post-intervention visits with 5 h postprandial blood draws and visual analog scales (VAS) for cholecystokinin (CCK), peptide YY (PYY), ghrelin, and subjective appetite, respectively. Participants also completed VAS questionnaires hourly and recorded dietary intake after leaving the lab for the remainder of the day. There was a greater increase in fasting CCK (CSO: 0.54 ± 0.03 to 0.56 ± 0.04; OO: 0.63 ± 0.07 to 0.60 ± 0.06 ng/ml p = 0.05), a greater suppression of postprandial ghrelin (p < 0.01), and a greater increase in postprandial VAS fullness (p = 0.04) in CSO compared to OO. Additionally, there was a greater decrease in self-reported energy intake in CSO compared to OO (CSO: 2464 ± 123 to 2115 ± 123; OO: 2263 ± 147 to 2,434 ± 184 kcal/d p = 0.02). Only postprandial VAS prospective consumption showed greater suppression (p = 0.03) in OO vs. CSO. Altogether, these data show that CSO has a greater effect on appetite suppression than OO diet enrichment and may be beneficial for weight maintenance, especially in a population at-risk for chronic disease. Registered at clinicaltrials.gov: NCT04397055.

A cottonseed oil-enriched diet improves liver and plasma lipid levels in a male mouse model of fatty liver.

A high-fat (HF) diet causes fatty liver, hyperlipidemia, and hypercholesterolemia, and cottonseed oil (CSO) has been shown to improve liver and plasma lipids in human and mouse models. The purpose of this study was to determine the effect of CSO vs. olive oil (OO)-enriched diets on lipid levels in a HF-diet model of fatty liver disease. We placed mice on a HF diet to induce obesity and fatty liver, after which mice were placed on CSO or OO diets, with chow and HF (5.1 kcal/g) groups as control. When CSO- and OO-fed mice were given isocaloric diets with the HF group, there were no differences in body weight, plasma, or hepatic lipids. However, when the CSO and OO diets were reduced in calories (4.0 kcal/g), CSO and OO groups reduced body weight. The CSO group had lower plasma total cholesterol (-56 ± 6%, P < 0.01), free cholesterol (-53 ± 7%, P < 0.01), triglycerides (-61 ± 14%, P < 0.01), and LDL (-42 ± 16%, P = 0.01) vs. HF group whereas the OO diet lowered LDL (-18 ± 12%, P = 0.05) vs. HF. Furthermore, the CSO diet decreased hepatic total cholesterol (-40 ± 12%, P < 0.01), free cholesterol (-23 ± 11%, P = 0.04), and triglycerides (-47 ± 12%, P = 0.02). There were no significant changes in lipogenesis and fatty acid oxidation among the groups. However, the CSO group increased lipid oxidative gene expression in liver and dihydrosterculic acid increased PPARα target genes with in vitro models. Taken together, consuming a reduced calorie diet enriched in CSO reduces liver and plasma lipid profiles in an obese model of fatty liver.

Angiopoietin-Like Protein Responses to Pecan-Enriched Diets Versus a Nut-Excluded Diet.

Daily pecan consumption improves fasting and postprandial triglycerides, but its effect on angiopoietin-like proteins (ANGPTLs) is unknown. The objective of this study was to investigate the impact of daily pecan consumption for 8 weeks on fasting and postprandial ANGPTL3, -8, and -4. This was an 8-week, randomized, controlled trial with three treatments: two pecan groups and a nut-free control group (n = 16). The ADD group (n = 15) consumed pecans (68 g) as part of a free-living diet, and the SUB group (n = 16) substituted the pecans (68 g) for isocaloric foods from their habitual diet. Fifty-six participants were randomized but nine subjects did not begin or finish the 8-week intervention and/or testing visits. At pre- and post-intervention, a high saturated fat meal was consumed with 3.5 h postprandial blood draws to determine changes in ANGPTL3, -8, and -4. There was a significant suppression in postprandial ANGPTL3 from pre- to post-intervention within ADD and SUB (P = .004 and P = .002, respectively) but not control (ns). There were no other changes within or between groups for fasting and postprandial outcomes. Daily pecan consumption improved postprandial ANGPTL3, which may mediate improvements in lipid metabolism.

Blood Lipid Responses to Diets Enriched with Cottonseed Oil Compared With Olive Oil in Adults with High Cholesterol in a Randomized Trial.

BACKGROUND: Increasing unsaturated fat intake is beneficial for cardiovascular health, but the type of unsaturated fat to recommend remains equivocal. OBJECTIVES: We investigated the effects of an 8-week diet intervention that was rich in either cottonseed oil (CSO; PUFA rich) or olive oil (OO; MUFA rich) on blood lipids in hypercholesterolemic adults. METHODS: Forty-three men and women with hypercholesterolemia (53 ± 10 years; BMI, 27.6 ± 4.8 kg/m2) completed this randomized parallel clinical trial consisting of an 8-week partial outpatient feeding intervention. Participants were given meals and snacks accounting for ∼60% of their daily energy needs, with 30% of energy needs from either CSO (n = 21) or OO (n = 22). At pre- and postdiet intervention visits, participants consumed a high-SFA meal (35% of total energy needs; 70% of energy from fat). The primary outcomes of fasting cholesterol profiles and secondary outcomes of postprandial blood lipids and glycemic markers were assessed over a 5-hour period. RESULTS: There were greater reductions from baseline to week 8 in fasting serum total cholesterol (TC; -17.0 ± 3.94 mg/dL compared with -2.18 ± 3.72 mg/dL, respectively; P = 0.008), LDL cholesterol (-19.7 ± 3.94 mg/dL compared with -5.72 ± 4.23 mg/dL, respectively; P = 0.018), non-HDL cholesterol (-20.8 mg/dL ± 4.00 compared with -6.61 ± 4.01 mg/dL, respectively; P = 0.014), and apoB (-11.8 mg/dL ± 2.37 compared with -3.10 ± 2.99 mg/dL, respectively; P = 0.05), in CSO compared with OO. There were also visit effects from baseline to week 8 for increases in HDL cholesterol (CSO, 56.5 ± 2.79 mg/dL to 60.2 ± 3.35 mg/dL, respectively; OO: 59.7 ± 2.63 mg/dL to 64.1 ± 2.24 mg/dL, respectively; P < 0.001), and decreases in the TC:HDL-cholesterol ratio (CSO, 4.30 ± 0.27 mg/dL to 3.78 ± 0.27 mg/dL, respectively; OO, 3.94 ± 0.16 mg/dL to 3.57 ± 0.11 mg/dL, respectively; P < 0.001), regardless of group assignment. In response to the high-SFA meal, there were differences in postprandial plasma glucose (P = 0.003) and triglyceride (P = 0.004) responses and a trend in nonesterified fatty acids (P = 0.11) between groups, showing protection in the postprandial state from an occasional high-SFA fat meal with CSO, but not OO, diet enrichment. CONCLUSIONS: CSO, but not OO, diet enrichment caused substantial improvements in fasting and postprandial blood lipids and postprandial glycemia in hypercholesterolemic adults. This trial was registered at clinicaltrials.gov as NCT04397055.

Pecan-enriched diets increase energy expenditure and fat oxidation in adults at-risk for cardiovascular disease in a randomised, controlled trial.

BACKGROUND: Research indicates that diets enriched with unsaturated fatty acids improve energy metabolism, although studies on tree nuts, which are a rich source of those fats, are limited. The present study aimed to examine the impact of daily pecan consumption for 8 weeks on energy metabolism in adults with hypercholesterolaemia or at higher risk for cardiovascular disease (CVD) (body mass index ≥ 28 kg m-2 ). METHODS: For this randomised, controlled trial, 56 sedentary adults were randomised into one of three treatments for an 8-week intervention: two pecan groups and a nut-free control group (n = 18). The ADD group (n = 16) consumed pecans as part of a free-living diet, whereas the SUB group (n = 18) substituted the pecans for isocaloric foods from their habitual diet. At baseline and 8 weeks, a high saturated fat meal was consumed along with indirect calorimetry measurements at fasting and for 4 h postprandially to determine changes in resting metabolic rate (RMR), diet induced thermogenesis (DIT) and substrate utilisation (primary outcomes). Forty-seven participants completed the trial and were included in analyses. RESULTS: In the SUB group, there was an increase in fasting RMR (1607 ± 117 to 1701 ± 114 kcal day-1 ; p = 0.01) and fasting fat oxidation (0.83 ± 0.08 to 0.99 ± 0.08 g/15 min; p = 0.009) and a decrease in fasting respiratory exchange ratio (0.85 ± 0.01 to 0.83 ± 0.01; p = 0.05) from pre- to post-intervention. In the ADD group, there was an increase in postprandial DIT (p < 0.001). There were no changes within the control group or between groups for any outcome measure. CONCLUSIONS: Daily consumption of pecans may increase select measures of energy expenditure and fat oxidation in adults at-risk for CVD.

Angiopoietin-1 protects 3T3-L1 preadipocytes from saturated fatty acid-induced cell death.

Cross talk between endothelial cells and adipocytes is vital to adipocyte functions, but little is known about the mechanisms or factors controlling the process. Angiogenesis is a critical component linking the endothelium to healthy adipogenesis, yet it is not known if or how it is involved in adipocyte physiology. Therefore, the purpose of this study was to determine the effect of angiopoietin-1 (Ang-1) and -2 (Ang-2) as well as their receptor, Tie-2, on adipocyte physiology. 3T3-L1 pre- and mature adipocytes were found to express Ang-1, Ang-2, and Tie-2, which decrease upon polyunsaturated fatty acid treatment. Furthermore, 3T3-L1 cells treated with recombinant Ang-1 or Ang-2 increased expression of the antiapoptotic gene Bcl-x and decreased expression of the proapoptotic gene Casp-8. Next, preadipocytes were treated with saturated fatty acids (SFAs) to induce cell stress. SFA-mediated splicing of X-box-binding protein-1 was reduced by co-treatment with Ang-1, and cell viability was improved in the presence of SFAs + Ang-1. Taken together, these results indicate that Ang-1 may protect preadipocytes from SFA-induced apoptosis and endoplasmic reticulum stress.

Sensory Analysis of a Processed Food Intended for Vitamin A Supplementation.

Provitamin A and pre-formed vitamin A compounds are essential micronutrients for humans. However, vitamin A deficiency (VAD) affects the health status of nearly 50% of populations in Southeast Asia and sub-Saharan Africa and is especially pronounced in preschool children and pregnant women. The objective of this research was to determine an acceptable flavor/ingredient combination to produce a palatable food product that incorporates sweet potatoes, peanut paste, and chickpeas. We sought to determine the acceptability of the three product formulations and to determine the influence of demographic data on ratings for the sensory attributes of each sample. To address VAD issues, three formulations of a product incorporating sweet potato puree (to increase ß-carotene content), pure peanut butter (to provide fat for ß-carotene absorption), and chickpeas (to provide a complete protein source), were developed: (1) an unflavored control, and two formulations with added natural seasonings: (2) curry-flavored, and (3) pumpkin spice-flavored. Sensory analysis of the three products showed that the curry-flavored product received the highest acceptability in terms of overall liking, flavor, texture, and appearance (p < 0.001). Since the demographic effect was not statistically significant (p > 0.05), it is highly likely that the curry-flavored product can be implemented in other countries or areas with high acceptability.

A 5-day high-fat diet rich in cottonseed oil improves cholesterol profiles and triglycerides compared to olive oil in healthy men.

Modifying dietary fat composition is important for minimizing cardiovascular disease risk. The purpose of this study was to determine the effects of a 5-day, high-fat diet rich in cottonseed oil (CSO) or olive oil (OO) on lipid profiles. Based on previous human and animal models, we hypothesized that the CSO-rich diet would lead to lower fasting and postprandial lipid levels, whereas the OO-rich diet would not significantly change lipid levels in 5 days. Fifteen normal-weight men completed a randomized crossover design with 2 controlled feeding trials (3-day lead-in diet, prediet visit, 5-day CSO- or OO-rich diet, postdiet visit). The 5-day diets (50% fat) were rich in either CSO or OO. At pre- and postdiet visits, subjects consumed test meals rich in the oil that coincided with their 5-day diet, and blood draws were performed. Fasting total cholesterol, low-density lipoprotein cholesterol, and triglycerides (TG) were lower following CSO diet intervention (total cholesterol: 148.40 ±â€¯6.39 to 135.93 ±â€¯6.31 mg/dL; low-density lipoprotein cholesterol: 92.20 ±â€¯5.57 to 78.13 ±â€¯5.60 mg/dL; TG: 80.11 ±â€¯4.91 to 56.37 ±â€¯5.46 mg/dL for pre- to postdiet, respectively; P < .05). High-density lipoprotein cholesterol increased following CSO diet intervention (46.67 ±â€¯2.41 to 50.24 ±â€¯2.20 mg/dL for pre- to postdiet, respectively; P < .05). Postprandial TGs were lower following CSO diet (area under the curve of 954.28 ±â€¯56.90 vs 722.16 ±â€¯56.15 mg/dL/8 h for pre- vs postdiet, respectively; P < .01). No changes in blood lipids were found following OO diet. A 5-day CSO-rich diet led to improvements in cholesterol and TGs, whereas no changes were observed with an OO-rich diet.

Metabolic responses to high-fat diets rich in MUFA v. PUFA.

Dietary fatty acid (FA) composition may influence metabolism, possibly affecting weight management. The purpose of this study was to compare the effects of a 5-d diet rich in PUFA v. MUFA. A total of fifteen normal-weight men participated in a randomised cross-over design with two feeding trials (3 d lead-in diet, pre-diet visit, 5-d PUFA- or MUFA-rich diet, post-diet visit). The 5-d diets (50 % fat) were rich in either PUFA (25 % of energy) or MUFA (25 % of energy). At pre- and post-diet visits, subjects consumed breakfast and lunch test meals, rich in the FA for that 5-d diet. Indirect calorimetry was used for 4 h after each meal. There were no treatment differences in fasting metabolism acutely or after the 5-d diet. For acute meal responses before diet, RER was higher for PUFA v. MUFA (0·86 (sem 0·01) v. 0·84 (sem 0·01), P<0·05), whereas diet-induced thermogenesis (DIT) was lower for PUFA v. MUFA (18·91 (SEM 1·46) v. 21·46 (SEM 1·34) kJ, P<0·05). After the 5-d diets, the change in RER was different for PUFA v. MUFA (-0·02 (sem 0·01) v. 0·00 (sem 0·01), P<0·05). Similarly, the change in fat oxidation was greater for PUFA v. MUFA (0·18 (sem 0·07) v. 0·04 (sem 0·06) g, P<0·05). In conclusion, acutely, a MUFA-rich meal results in lower RER and greater DIT. However, after a 5-d high-fat diet, the change in metabolic responses was greater in the PUFA diet, showing the metabolic adaptability of a PUFA-rich diet.

Dihydrosterculic acid from cottonseed oil suppresses desaturase activity and improves liver metabolomic profiles of high-fat-fed mice.

Polyunsaturated fatty acid (PUFA)-rich diets are thought to provide beneficial effects toward metabolic health in part through their bioactive properties. We hypothesized that increasing PUFA intake in mice would increase peroxisome proliferator activated receptor delta (PPARδ) expression and activity, and we sought to examine the effect of different PUFA-enriched oils on muscle PPARδ expression. One of the oils we tested was cottonseed oil (CSO) which is primarily linoleic acid (53%) and palmitic acid (24%). Mice fed a CSO-enriched diet (50% energy from fat) displayed no change in muscle PPARδ expression; however, in the liver, it was consistently elevated along with its transcriptional coactivator Pgc-1. Male mice were fed chow or CSO-, saturated fat (SFA)-, or linoleic acid (18:2)-enriched diets that were matched for macronutrient content for 4 weeks. There were no differences in food intake, body weight, fasting glucose, glucose tolerance, or energy expenditure between chow- and CSO-fed mice, whereas SFA-fed mice had increased fat mass and 18:2-fed mice were less glucose tolerant. Metabolomic analyses revealed that the livers of CSO-fed mice closely matched those of chow-fed but significantly differed from SFA- and 18:2-enriched groups. Fatty acid composition of the diets and livers revealed an impairment in desaturase activity and the presence of dihydrosterculic acid (DHSA) in the CSO-fed mice. The effect of DHSA on PPARδ and stearoyl-CoA desaturase-1 expression mimicked that of the CSO-fed mice. Taken together, these data suggest that DHSA from CSO may be an effective means to increase PPARδ expression with concomitant suppression of liver stearoyl-CoA desaturase-1 activity.

Hunger and satiety responses to high-fat meals after a high-polyunsaturated fat diet: A randomized trial.

OBJECTIVE: Previous studies have shown that polyunsaturated fats (PUFAs) elicit a greater response in satiety after a single-meal challenge compared with other types of fats. The long-term effects of PUFAs on satiety, however, remain unknown. The aim of this study was to determine subjective and physiological hunger and satiety responses to high-fat (HF) meals before and after a 7-d PUFA-rich diet. METHODS: Twenty-six, healthy weight (body mass index 18-24.9 kg/m2), sedentary adults were randomly assigned to either a 7-d PUFA-rich diet (n = 8 men and n = 8 women) or a 7-d control diet (n = 5 men and n = 5 women). After a 3-d lead-in diet, participants reported for the baseline visit where anthropometrics, fasting visual analog scale (VAS) measurements, and a fasting blood sample were collected. Then, two HF meals (breakfast and lunch) were consumed. Postprandial blood draws and VAS measures were collected approximately every 30 min for 4 h after each meal, for a total of 8 h. RESULTS: From pre- to post-PUFA-rich diet, there was a decrease in fasting ghrelin (P < 0.05) and an increase in fasting peptide YY (PYY; P < 0.05); however, there were no changes in fasting insulin or leptin concentrations. The postprandial response for PYY was higher after the PUFA-rich diet visit compared to baseline (P < 0.01). However, there were no differences in the postprandial response for ghrelin, insulin, leptin, or VAS measures from pre- to post-diet in either the PUFA-rich diet or control (ns). CONCLUSION: A PUFA-rich diet consumed for 7 d favorably altered fasting and postprandial physiological markers of hunger and satiety; yet, did not alter subjective ratings of hunger or fullness.

Impact of dietary fat composition on prediabetes: a 12-year follow-up study.

OBJECTIVE: Dietary fatty acid composition likely affects prediabetic conditions such as isolated impaired fasting glucose (IFG) or impaired glucose tolerance (IGT); however, this risk has not been evaluated in a large population nor has it been followed prospectively. DESIGN: Diet, physical activity, anthropometric, socio-economic and blood glucose data from the Atherosclerosis Risk in Communities (ARIC) study were obtained from BioLINCC. Cox proportional hazards regression models were used to evaluate associations of dietary SFA, MUFA, PUFA, n-3 fatty acid (FA) and n-6 FA intakes with incidence of one (isolated IFG) or two (IFG with IGT) prediabetic conditions at the end of 12-year follow-up. SETTING: Study volunteers were from counties in North Carolina, Mississippi, Minnesota and Maryland, USA. SUBJECTS: Data from 5288 volunteers who participated in the ARIC study were used for all analyses reported herein. RESULTS: The study population was 62% male and 84 % white, mean age 53·5 (sd 5·7) years and mean BMI 26·2 (sd 4·6) kg/m2. A moderately high intake of dietary MUFA (10-15 % of total daily energy) was associated with a 10 % reduced risk of isolated IFG incidence, while a high intake of n-3 FA (>0·15 % of total daily energy) was associated with a 10 % increase in risk. Curiously, moderately high intake of n-6 PUFA (4-5 % of total daily energy) was associated with a 12 % reduction in IFG and IGT incidence. CONCLUSIONS: MUFA, n-3 and n-6 FA contribute differently to the development of isolated IFG v. IFG with IGT; and their mechanism may be more complex than originally proposed.

A PUFA-rich diet improves fat oxidation following saturated fat-rich meal.

PURPOSE: To determine substrate oxidation responses to saturated fatty acid (SFA)-rich meals before and after a 7-day polyunsaturated fatty acid (PUFA)-rich diet versus control diet. METHODS: Twenty-six, normal-weight, adults were randomly assigned to either PUFA or control diet. Following a 3-day lead-in diet, participants completed the pre-diet visit where anthropometrics and resting metabolic rate (RMR) were measured, and two SFA-rich HF meals (breakfast and lunch) were consumed. Indirect calorimetry was used to determine fat oxidation (Fox) and energy expenditure (EE) for 4 h after each meal. Participants then consumed a PUFA-rich diet (50 % carbohydrate, 15 % protein, 35 % fat, of which 21 % of total energy was PUFA) or control diet (50 % carbohydrate, 15 % protein, 35 % fat, of which 7 % of total energy was PUFA) for the next 7 days. Following the 7-day diet, participants completed the post-diet visit. RESULTS: From pre- to post-PUFA-rich diet, there was no change in RMR (16.3 ± 0.8 vs. 16.4 ± 0.8 kcal/20 min) or in incremental area under the curve for EE (118.9 ± 20.6-126.9 ± 14.1 kcal/8h, ns). Fasting respiratory exchange ratio increased from pre- to post-PUFA-rich diet only (0.83 ± 0.1-0.86 ± 0.1, p < 0.05). The postprandial change in Fox increased from pre- to post-visit in PUFA-rich diet (0.03 ± 0.1-0.23 ± 0.1 g/15 min for cumulative Fox; p < 0.05), whereas controls showed no change. CONCLUSIONS: Adopting a PUFA-rich diet initiates greater fat oxidation after eating occasional high SFA meals compared to a control diet, an effect achieved in 7 days.

Acute effect of dietary fatty acid composition on postprandial metabolism in women.

The composition of fatty acids in a diet may differentially affect metabolism, thus playing a role in the development of obesity. Our aim was to study the effects of three high-fat (HF) meals with different degrees of saturation on diet-induced thermogenesis (DIT) and substrate oxidation in premenopausal women of normal weight. Fifteen healthy, normal-weight women, aged 18-35 years, participated in a randomized cross-over study, in which they consumed isocaloric HF meals (70% of energy from fat) rich in saturated fat (SFA; 40% of total energy), monounsaturated fat (MUFA; 42% of total energy) or polyunsaturated fat (PUFA; 42% of total energy). Indirect calorimetry was used to measure respiratory gases for a 5 h postprandial period. The data collected were used to determine respiratory exchange ratio for assessing substrate oxidation, as well as energy expenditure for the determination of DIT. The area under the curve for DIT following the PUFA-rich HF meal was greater than that of the SFA- or MUFA-rich HF meals [10.0 ± 0.7, 8.6 ± 0.8 and 8.9 ± 1.2 kcal (5 h)(-1) (P = 0.02) for PUFA, MUFA and SFA, respectively]. No significant difference was found in respiratory exchange ratio (0.86 ± 0.01, 0.85 ± 0.01 and 0.85 ± 0.01 for PUFA-, MUFA- and SFA-rich HF meals, respectively) or substrate utilization following the three different HF meals (12.2 ± 1.0, 11.2 ± 0.5 and 11.6 ± 0.9 g for cumulative postprandial carbohydrate oxidation following the PUFA-, MUFA- and SFA-rich HF meals, respectively; and 3.8 ± 0.4, 4.1 ± 0.2 and 4.1 ± 0.3 g for cumulative fat oxidation of the PUFA-, MUFA- and SFA-rich HF meals, respectively). In conclusion, acute ingestion of a PUFA-rich HF meal induced a greater DIT in normal-weight women compared with SFA- or MUFA-rich HF meals. No significant differences were found for substrate utilization.