Xiaoran Liu

DHA-enriched high–oleic acid canola oil improves lipid profile and lowers predicted cardiovascular disease risk in the canola oil multicenter randomized controlled trial

BACKGROUND It is well recognized that amounts of trans and saturated fats should be minimized in Western diets; however, considerable debate remains regarding optimal amounts of dietary n-9, n-6, and n-3 fatty acids. OBJECTIVE The objective was to examine the effects of varying n-9, n-6, and longer-chain n-3 fatty acid composition on markers of coronary heart disease (CHD) risk. DESIGN A randomized, double-blind, 5-period, crossover design was used. Each 4-wk treatment period was separated by 4-wk washout intervals. Volunteers with abdominal obesity consumed each of 5 identical weight-maintaining, fixed-composition diets with one of the following treatment oils (60 g/3000 kcal) in beverages: 1) conventional canola oil (Canola; n-9 rich), 2) high-oleic acid canola oil with docosahexaenoic acid (CanolaDHA; n-9 and n-3 rich), 3) a blend of corn and safflower oil (25:75) (CornSaff; n-6 rich), 4) a blend of flax and safflower oils (60:40) (FlaxSaff; n-6 and short-chain n-3 rich), or 5) high-oleic acid canola oil (CanolaOleic; highest in n-9). RESULTS One hundred thirty individuals completed the trial. At endpoint, total cholesterol (TC) was lowest after the FlaxSaff phase (P < 0.05 compared with Canola and CanolaDHA) and highest after the CanolaDHA phase (P < 0.05 compared with CornSaff, FlaxSaff, and CanolaOleic). Low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol were highest, and triglycerides were lowest, after CanolaDHA (P < 0.05 compared with the other diets). All diets decreased TC and LDL cholesterol from baseline to treatment endpoint (P < 0.05). CanolaDHA was the only diet that increased HDL cholesterol from baseline (3.5 ± 1.8%; P < 0.05) and produced the greatest reduction in triglycerides (-20.7 ± 3.8%; P < 0.001) and in systolic blood pressure (-3.3 ± 0.8%; P < 0.001) compared with the other diets (P < 0.05). Percentage reductions in Framingham 10-y CHD risk scores (FRS) from baseline were greatest after CanolaDHA (-19.0 ± 3.1%; P < 0.001) than after other treatments (P < 0.05). CONCLUSION Consumption of CanolaDHA, a novel DHA-rich canola oil, improves HDL cholesterol, triglycerides, and blood pressure, thereby reducing FRS compared with other oils varying in unsaturated fatty acid composition. This trial was registered at www.clinicaltrials.gov as NCT01351012.

Effect of plant sterol-enriched diets on plasma and egg yolk cholesterol concentrations and cholesterol metabolism in laying hens

Egg exists as a major dietary source of cholesterol in Western diets. In North America, laying hen diets are usually devoid of cholesterol when diets are formulated to exclude animal-based products. Hence, laying hens meet their physiological cholesterol requirement through de novo synthesis. Plant sterols exert a cholesterol-lowering effect in humans by interfering with intestinal sterol absorption. However, it is unknown whether plant sterol supplementation could be effective in reducing intestinal reabsorption of biliary cholesterol in laying hens, thus modulating whole body cholesterol in favor of lower plasma and yolk cholesterol content. The current study was designed to investigate the effect of diets enriched with 0, 0.5, 1, and 2% plant sterols on cholesterol absorption, synthesis, as well as plasma, liver, and egg yolk cholesterol concentrations in laying hens. After 8 wk of plant sterol intervention (first 2 wk were acclimatization), feed intake, BW, egg weight, egg yolk weight, egg production, Haugh units, liver mass, plasma, and hepatic cholesterol concentrations did not differ as a function of plant sterol supplementation. Egg cholesterol concentrations (mg/g) fluctuated during the 6-wk experimental period. At wk 6, a minor reduction in egg yolk cholesterol concentration (mg per g of yolk, P<0.05, vs. control) was observed in hens fed 1 and 2% cholesterol-enriched diets, respectively. However, such result failed to affect total egg cholesterol content. No statistical difference was observed across treatments over 6 wk. Neither cholesterol absorption rates nor synthesis differed as a function of treatment. Results suggested that overall cholesterol content in egg yolk was not affected by feeding hens plant sterol-enriched diets over 6 wk.

Plasma fatty acid changes following consumption of dietary oils containing n-3, n-6, and n-9 fatty acids at different proportions: preliminary findings of the Canola Oil Multicenter Intervention Trial (COMIT)

BackgroundThe Canola Oil Multicenter Intervention Trial (COMIT) was a randomized controlled crossover study designed to evaluate the effects of five diets that provided different oils and/or oil blends on cardiovascular disease (CVD) risk factors in individuals with abdominal obesity. The present objective is to report preliminary findings on plasma fatty acid profiles in volunteers with abdominal obesity, following the consumption of diets enriched with n-3, n-6 and n-9 fatty acids.MethodsCOMIT was conducted at three clinical sites, Winnipeg, Manitoba, Canada, Québec City, Québec, Canada and University Park, Pennsylvania, United States. Inclusion criteria were at least one of the followings: waist circumference (≥90 cm for males and ≥84 cm for females), and at least one other criterion: triglycerides ≥1.7 mmol/L, high density lipoprotein cholesterol <1 mmol/L (males) or <1.3 mmol/L (females), blood pressure ≥130 mmHg (systolic) and/or ≥85 mmHg (diastolic), and glucose ≥5.5 mmol/L. Weight-maintaining diets that included shakes with one of the dietary oil blends were provided during each of the five 30-day dietary phases. Dietary phases were separated by four-week washout periods. Treatment oils were canola oil, high oleic canola oil, high oleic canola oil enriched with docosahexaenoic acid (DHA), flax oil and safflower oil blend, and corn oil and safflower oil blend. A per protocol approach with a mixed model analysis was decided to be appropriate for data analysis.ResultsOne hundred and seventy volunteers were randomized and 130 completed the study with a dropout rate of 23.5%. The mean plasma total DHA concentrations, which were analyzed among all participants as a measure of adherence, increased by more than 100% in the DHA-enriched phase, compared to other phases, demonstrating excellent dietary adherence.ConclusionsRecruitment and retention strategies were effective in achieving a sufficient number of participants who completed the study protocol to enable sufficient statistical power to resolve small differences in outcome measures. It is expected that the study will generate important data thereby enhancing our understanding of the effects of n-3, n-6, and n-9 fatty acid-containing oils on CVD risks.Trial registrationClinicalTrials.gov NCT01351012.

Interactions between dietary oil treatments and genetic variants modulate fatty acid ethanolamides in plasma and body weight composition

Fatty acid ethanolamides (FAE), a group of lipid mediators derived from long-chain fatty acids (FA), mediate biological activities including activation of cannabinoid receptors, stimulation of fat oxidation and regulation of satiety. However, how circulating FAE levels are influenced by FA intake in humans remains unclear. The objective of the present study was to investigate the response of six major circulating FAE to various dietary oil treatments in a five-period, cross-over, randomised, double-blind, clinical study in volunteers with abdominal obesity. The treatment oils (60 g/12 552 kJ per d (60 g/3000 kcal per d)) provided for 30 d were as follows: conventional canola oil, high oleic canola oil, high oleic canola oil enriched with DHA, flax/safflower oil blend and corn/safflower oil blend. Two SNP associated with FAE degradation and synthesis were studied. Post-treatment results showed overall that plasma FAE levels were modulated by dietary FA and were positively correlated with corresponding plasma FA levels; minor allele (A) carriers of SNP rs324420 in gene fatty acid amide hydrolase produced higher circulating oleoylethanolamide (OEA) (P=0·0209) and docosahexaenoylethanolamide (DHEA) levels (P=0·0002). In addition, elevated plasma DHEA levels in response to DHA intake tended to be associated with lower plasma OEA levels and an increased gynoid fat mass. In summary, data suggest that the metabolic and physiological responses to dietary FA may be influenced via circulating FAE. Genetic analysis of rs324420 might help identify a sub-population that appears to benefit from increased consumption of DHA and oleic acid.

Effects of canola and high‐oleic‐acid canola oils on abdominal fat mass in individuals with central obesity

To determine the effect of diets low in saturated fatty acids and high in monounsaturated fatty acids (MUFA) or polyunsaturated fatty acids on body composition in participants at risk for metabolic syndrome (MetS).

Acute Peanut Consumption Alters Postprandial Lipids and Vascular Responses in Healthy Overweight or Obese Men

Background: Postprandial hyperlipidemia is associated with impaired endothelial function. Peanut consumption favorably affects the lipid and lipoprotein profile; however, the effects on endothelial function remain unclear. Objective: The purpose of the study was to evaluate the effects of acute peanut consumption as part of a high-fat meal on postprandial endothelial function. Methods: We conducted a randomized, controlled, crossover postprandial study to evaluate the effect of acute peanut consumption on postprandial lipids and endothelial function as assessed by flow-mediated dilatation (FMD) of the brachial artery in 15 healthy overweight or obese men [mean age: 26.7 y; mean body mass index (in kg/m2): 31.4]. Participants consumed, in a randomized order, a peanut meal containing 3 ounces (85 g) ground peanuts (1198 kcal; 40.0% carbohydrate, 47.7% fat, 19.4% saturated fat, 13.2% protein) and a control meal matched for energy and macronutrient content. Meals were in the form of a shake, scheduled ≥1 wk apart. Lipids, lipoproteins, glucose, and insulin were measured at baseline (0 min) and at 30, 60, 120, and 240 min after shake consumption. FMD was measured at baseline and at 240 min. Results: Acute peanut consumption blunted the serum triglyceride (TG) response 120 and 240 min after consumption compared with the control meal (means ± SEMs—120 min: 188.9 ± 19.4 compared with 197.5 ± 20.7 mg/dL; 240 min: 189.9 ± 24.3 compared with 197.3 ± 18.4 mg/dL; P < 0.05 for both). Total, LDL, and HDL cholesterol and glucose and insulin responses were similar between the test meals. Compared with baseline, only the control meal significantly decreased FMD at 240 min (control: −1.2% ± 0.5%; P = 0.029; peanut: −0.6% ± 0.5%; P = 0.3). Participants with higher baseline total (>150 mg/dL) and LDL (>100 mg/dL)-cholesterol concentrations showed a significant decrease in FMD after the control meal (−1.8%, P = 0.017; −2.0%, P = 0.038), whereas the peanut meal maintained endothelial function in all participants irrespective of total- and LDL-cholesterol concentrations. Conclusion: The inclusion of 85 g peanuts (3 ounces) as part of a high-fat meal improved the postprandial TG response and preserved endothelial function in healthy overweight or obese men. This trial was registered at clinicaltrials.gov as NCT01405300.

Trans -8, cis -10+ cis -9, trans -11-conjugated linoleic acid mixture alters body composition in Syrian golden hamsters fed a hypercholesterolaemic diet

The effectiveness of conjugated linoleic acid (CLA) as a weight-loss nutraceutical continues to be debatable, suggesting that there may be value in exploring the physiological effects of the lesser-known isomers. The effects of the minor isomer, trans-8, cis-10 (t8, c10)-CLA, in the form of an equimolar mixture with the cis-9, trans-11 (c9, t11) isomer, on body weight and body composition, circulating glucose and lipid concentrations, and liver weights were studied in sixty male Syrian golden hamsters. Animals were randomised to receive for 28 d a semi-purified, hypercholesterolaemic diet (5% dietary fat and 0.25% cholesterol) supplemented at the 2% level with either the t8, c10+c9, t11-CLA mixture, c9, t11-CLA or trans-10, cis-12 (t10, c12)-CLA replacing lard and safflower-seed oil (control). Results show that compared with control, the t8, c10+c9, t11-CLA mixture and t10, c12-CLA-fed animals had lower (P < 0.0001) fat mass following supplementation. Animals consuming t10, c12-CLA also possessed higher lean mass compared with control and c9, t11-CLA groups (P < 0.001). However, the livers of these animals were larger (P < 0.0001) compared with those in the control and other CLA groups. Body weights of the hamsters did not differ across the experimental groups. CLA treatments had no effect on serum glucose or lipid profile, except for inducing higher (P < 0.05) non-HDL-cholesterol concentration with t10, c12-CLA compared with the c9, t11 isomer. Overall, these results indicate that in male hamsters fed a hypercholesterolaemic diet, the t8, c10+c9, t11-CLA mixture does not have an impact on blood lipid profile, but is able to effectively reduce fat mass, without incurring an accompanying liver enlargement.