Jennifer A. Fleming

Determinants of Erythrocyte Omega‐3 Fatty Acid Content in Response to Fish Oil Supplementation: A Dose–Response Randomized Controlled Trial

Background The erythrocyte membrane content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which constitutes the omega‐3 index (O3I), predicts cardiovascular disease mortality. The amount of EPA+DHA needed to achieve a target O3I is poorly defined, as are the determinants of the O3I response to a change in EPA+DHA intake. The objective of this study was to develop a predictive model of the O3I response to EPA+DHA supplementation in healthy adults, specifically identifying factors that determine the response. Methods and Results A randomized, placebo‐controlled, double‐blind, parallel‐group study was conducted in 115 healthy men and women. One of 5 doses (0, 300, 600, 900, 1800 mg) of EPA+DHA was given daily as placebo or fish oil supplements for ≈5 months. The O3I was measured at baseline and at the end of the study. There were no significant differences in the clinical characteristics between the groups at baseline. The O3I increased in a dose‐dependent manner (P<0.0001), with the dose of EPA+DHA alone accounting for 68% (quadratic, P<0.0001) of the variability in the O3I response. Dose adjusted per unit body weight (g/kg) accounted for 70% (linear, P<0.0001). Additional factors that improved prediction of treatment response were baseline O3I, age, sex, and physical activity. Collectively, these explained 78% of the response variability (P<0.0001). Conclusions Our findings validate the O3I as a biomarker of EPA+DHA consumption and identify additional factors, particularly body weight, that can be used to tailor EPA+DHA recommendations to achieve a target O3I.

The Evidence for α-Linolenic Acid and Cardiovascular Disease Benefits: Comparisons with Eicosapentaenoic Acid and Docosahexaenoic Acid

Our understanding of the cardiovascular disease (CVD) benefits of α-linolenic acid (ALA, 18:3n-3) has advanced markedly during the past decade. It is now evident that ALA benefits CVD risk. The expansion of the ALA evidence base has occurred in parallel with ongoing research on eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) and CVD. The available evidence enables comparisons to be made for ALA vs. EPA + DHA for CVD risk reduction. The epidemiologic evidence suggests comparable benefits of plant-based and marine-derived n-3 (omega-3) PUFAs. The clinical trial evidence for ALA is not as extensive; however, there have been CVD event benefits reported. Those that have been reported for EPA + DHA are stronger because only EPA + DHA differed between the treatment and control groups, whereas in the ALA studies there were diet differences beyond ALA between the treatment and control groups. Despite this, the evidence suggests many comparable CVD benefits of ALA vs. EPA + DHA. Thus, we believe that it is time to revisit what the contemporary dietary recommendation should be for ALA to decrease the risk of CVD. Our perspective is that increasing dietary ALA will decrease CVD risk; however, randomized controlled clinical trials are necessary to confirm this and to determine what the recommendation should be. With a stronger evidence base, the nutrition community will be better positioned to revise the dietary recommendation for ALA for CVD risk reduction.

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 a Moderate Fat Diet With and Without Avocados on Lipoprotein Particle Number, Size and Subclasses in Overweight and Obese Adults: A Randomized, Controlled Trial

Background Avocados are a nutrient‐dense source of monounsaturated fatty acids (MUFA) that can be used to replace saturated fatty acids (SFA) in a diet to lower low density lipoprotein cholesterol (LDL‐C). Well‐controlled studies are lacking on the effect of avocado consumption on cardiovascular disease (CVD) risk factors. Methods and Results A randomized, crossover, controlled feeding trial was conducted with 45 overweight or obese participants with baseline LDL‐C in the 25th to 90th percentile. Three cholesterol‐lowering diets (6% to 7% SFA) were fed (5 weeks each): a lower‐fat diet (LF: 24% fat); 2 moderate‐fat diets (34% fat) provided similar foods and were matched for macronutrients and fatty acids: the avocado diet (AV) included one fresh Hass avocado (136 g) per day, and the moderate‐fat diet (MF) mainly used high oleic acid oils to match the fatty acid content of one avocado. Compared with baseline, the reduction in LDL‐C and non‐high‐density lipoprotein (HDL) cholesterol on the AV diet (−13.5 mg/dL, −14.6 mg/dL) was greater (P<0.05) than the MF (−8.3 mg/dL, −8.7 mg/dL) and LF (−7.4 mg/dL, −4.8 mg/dL) diets. Furthermore, only the AV diet significantly decreased LDL particle number (LDL‐P, −80.1 nmol/L, P=0.0001), small dense LDL cholesterol (LDL3+4, −4.1 mg/dL, P=0.04), and the ratio of LDL/HDL (−6.6%, P<0.0001) from baseline. Conclusions Inclusion of one avocado per day as part of a moderate‐fat, cholesterol‐lowering diet has additional LDL‐C, LDL‐P, and non‐HDL‐C lowering effects, especially for small, dense LDL. Our results demonstrate that avocados have beneficial effects on cardio‐metabolic risk factors that extend beyond their heart‐healthy fatty acid profile. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01235832.

The role of diet and nutritional supplements in preventing and treating cardiovascular disease.

Purpose of review Healthy lifestyle practices play a key role in preventing and treating cardiovascular disease, and central to such strategy is a recommended dietary pattern. Current Dietary Guidelines from the US Department of Agriculture and the American Heart Association advocate a food-based diet for optimal health and prevention of chronic disease. Considerable research has focused on implementing these guidelines for maximal cardiovascular risk reduction, and this review will discuss the role of specific dietary strategies and select nutrition supplements in achieving this goal. Recent findings Food-based guidelines are reflected in specific dietary approaches to improve cardiovascular risk factors, such as the Dietary Approaches to Stop Hypertension diet and Therapeutic Lifestyle Changes, which have shown to effectively benefit hypertension and hypercholesterolemia, respectively. These diets, therefore, significantly reduce coronary heart disease risk. Although such dietary approaches ensure that nutrient requirements are met through foods, nutrition supplement use in the United States is at an all time high. Summary The Dietary Approaches to Stop Hypertension diet and Therapeutic Lifestyle Changes Diet are effective in decreasing cardiovascular morbidity and mortality risk, and such dietary strategies are endorsed by many organizations, including the American Heart Association and the National Heart, Lung and Blood Institute. In contrast, although some dietary supplements, such as fish oil and niacin, have shown promising cardiovascular effects, justifying their widespread use in clinical practice for some patients, there is insufficient evidence for others. Clinicians should carefully evaluate the claims made for new diet therapies, supplements, or both when counseling at-risk individuals.

Effects of supplemental long-chain omega-3 fatty acids and erythrocyte membrane fatty acid content on circulating inflammatory markers in a randomized controlled trial of healthy adults.

The long-chain omega-3 polyunsaturated (n-3 PUFA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), may have anti-inflammatory effects. We evaluated the dose-response effect of EPA+DHA supplementation on circulating TNF-α, IL-6, and CRP and explored associations between red blood cell (RBC) membrane PUFA content and TNF-α, IL-6, and CRP. Young adults with low fish intake (n=116) received one of five doses (0, 300, 600, 900, or 1,800 mg/d EPA+DHA) for 5 months. There were no significant effects of supplemental EPA+DHA on IL-6 or CRP; however, there was a marginal treatment effect for TNF-α (p<0.08). At baseline, higher quartiles of RBC DHA were associated with lower TNF-α (p=0.001); higher quartiles of arachidonic acid were associated with higher TNF-α (p=0.005). EPA+DHA supplementation had no dose-response effect on TNF-α, IL-6, or CRP in healthy young adults; however, associations between inflammatory markers and RBC PUFA warrant further investigation.

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.

Effects of daily almond consumption on cardiometabolic risk and abdominal adiposity in healthy adults with elevated LDL-cholesterol: a randomized controlled trial.

Background Evidence consistently shows that almond consumption beneficially affects lipids and lipoproteins. Almonds, however, have not been evaluated in a controlled‐feeding setting using a diet design with only a single, calorie‐matched food substitution to assess their specific effects on cardiometabolic risk factors. Methods and Results In a randomized, 2‐period (6 week/period), crossover, controlled‐feeding study of 48 individuals with elevated LDL‐C (149±3 mg/dL), a cholesterol‐lowering diet with almonds (1.5 oz. of almonds/day) was compared to an identical diet with an isocaloric muffin substitution (no almonds/day). Differences in the nutrient profiles of the control (58% CHO, 15% PRO, 26% total fat) and almond (51% CHO, 16% PRO, 32% total fat) diets were due to nutrients inherent to each snack; diets did not differ in saturated fat or cholesterol. The almond diet, compared with the control diet, decreased non‐HDL‐C (−6.9±2.4 mg/dL; P=0.01) and LDL‐C (−5.3±1.9 mg/dL; P=0.01); furthermore, the control diet decreased HDL‐C (−1.7±0.6 mg/dL; P<0.01). Almond consumption also reduced abdominal fat (−0.07±0.03 kg; P=0.02) and leg fat (−0.12±0.05 kg; P=0.02), despite no differences in total body weight. Conclusions Almonds reduced non‐HDL‐C, LDL‐C, and central adiposity, important risk factors for cardiometabolic dysfunction, while maintaining HDL‐C concentrations. Therefore, daily consumption of almonds (1.5 oz.), substituted for a high‐carbohydrate snack, may be a simple dietary strategy to prevent the onset of cardiometabolic diseases in healthy individuals. Clinical Trial Registration URL: www.clinicaltrials.gov; Unique Identifier: NCT01101230.

Walnut oil increases cholesterol efflux through inhibition of stearoyl CoA desaturase 1 in THP-1 macrophage-derived foam cells.

BackgroundWalnuts significantly decrease total and low-density lipoprotein cholesterol in normo- and hypercholesterolemic individuals. No study to date has evaluated the effects of walnuts on cholesterol efflux, the initial step in reverse cholesterol transport, in macrophage-derived foam cells (MDFC). The present study was conducted to investigate the mechanisms by which walnut oil affects cholesterol efflux.MethodsThe extract of English walnuts (walnut oil) was dissolved in DMSO and applied to cultured THP-1 MDFC cells (0.5 mg/mL). THP-1 MDFC also were treated with human sera (10%, v:v) taken from subjects in a walnut feeding study. Cholesterol efflux was examined by liquid scintillation counting. Changes in gene expression were quantified by real time PCR.ResultsWalnut oil treatment significantly increased cholesterol efflux through decreasing the expression of the lipogenic enzyme stearoyl CoA desaturase 1 (SCD1) in MDFC. Alpha-linolenic acid (ALA), the major n-3 polyunsaturated fatty acids found in walnuts, recaptured SCD1 reduction in MDFC, a mechanism mediated through activation of nuclear receptor farnesoid-X-receptor (FXR). Postprandial serum treatment also increased cholesterol efflux in MDFC. When categorized by baseline C-reactive protein (CRP; cut point of 2 mg/L), subjects in the lower CRP sub-group benefited more from dietary intervention, including a more increase in cholesterol efflux, a greater reduction in SCD1, and a blunted postprandial lipemia.ConclusionIn conclusion, walnut oil contains bioactive molecules that significantly improve cholesterol efflux in MDFC. However, the beneficial effects of walnut intake may be reduced by the presence of a pro-inflammatory state.Trial RegistrationClinicalTrials.gov: NCT00938340

Weight Loss and Lowering Androgens Predict Improvements in Health-Related Quality of Life in Women With PCOS

CONTEXT Polycystic ovary syndrome (PCOS) is associated with reduced health-related quality of life (HRQOL) and increased prevalence of depressive and anxiety disorders. The impact of PCOS-specific treatments on these co-morbidities is unclear. OBJECTIVE To assess the impact of weight loss and decreasing hyperandrogenism on HRQOL and mood and anxiety disorders in women with PCOS. DESIGN/SETTING/PARTICIPANTS A secondary analysis of a randomized controlled trial (OWL-PCOS) of preconception treatment conducted at two academic centers in women (age, 18-40 years; body mass index, 27-42 kg/m(2)) with PCOS defined by Rotterdam criteria. INTERVENTION Continuous oral contraceptive pill (OCP) or intensive lifestyle intervention or the combination (Combined) for 16 weeks. MAIN OUTCOME MEASURE(S) Changes in HRQOL assessed by PCOSQ and SF-36 and prevalence of depression and anxiety disorder assessed by PRIME-MD PHQ. RESULTS The lowest scores were noted on the general health domain of the SF-36 and the weight and infertility domains on the PCOSQ. All three interventions resulted in significant improvement in the general health score on the SF-36. Both the OCP and Combined groups showed improvements in all domains of the PCOSQ (P < .01) compared to baseline scores. The Combined group had significant improvements in the weight, body hair, and infertility domains compared to a single treatment group (P < .05). In a linear regression model, change in weight correlated with improvements in the weight domain (P < .001) and physical well-being (P < .02), change in T correlated with improvements in the hair domain (P < .001), and change in both weight and T correlated with the infertility (P < .001) and menstrual domains (P < .05). CONCLUSIONS Both weight loss and OCP use result in significant improvements in several physical and mental domains related to quality of life, depressive symptoms, and anxiety disorders, and combined therapies offer further benefits in overweight/obese women with PCOS.