Elena Jovanovski

Viscosity rather than quantity of dietary fibre predicts cholesterol-lowering effect in healthy individuals

The well-documented lipid-lowering effects of fibre may be related to its viscosity, a phenomenon that has been understudied, especially when fibre is given against the background of a typical North American (NA) diet. In this three-arm experiment, we compared the lipid-lowering effect of low-viscosity wheat bran (WB), medium-viscosity psyllium (PSY) and a high-viscosity viscous fibre blend (VFB), as part of a fibre intervention aimed at increasing fibre intake to recommended levels within the context of a NA diet in apparently healthy individuals. Using a randomised cross-over design, twenty-three participants (twelve males and eleven females; age 35 (SD 12) years; LDL-cholesterol (C) 2.9 (SEM 0.6) mmol/l) consuming a typical NA diet received a standard, fibre-enriched cereal, where approximately one-third of the fibre was either a low-viscosity (570 centipoise (cP)) WB, medium-viscosity (14,300 cP) PSY or a high-viscosity (136,300 cP) novel VFB, for 3 weeks separated by washout periods of ≥ 2 weeks. There were no differences among the treatments in the amount of food consumed, total dietary fibre intake, reported physical activity and body weight. Final intake of the WB, PSY and VFB was 10.8, 9.0 and 5.1 g, respectively. Reduction in LDL-C was greater with the VFB compared with the medium-viscosity PSY (-12.6 (SEM 3.5) %, P = 0.002) and low-viscosity WB (-14.6 (SEM 4.2) %, P = 0.003). The magnitude of LDL-C reduction showed a positive association with fibre apparent viscosity (r - 0.41, P = 0.001). Despite the smaller quantity consumed, the high-viscosity fibre lowered LDL-C to a greater extent than lower-viscosity fibres. These data support the inclusion of high-viscosity fibre in the diet to reduce plasma lipids among apparently healthy individuals consuming a typical NA diet.

Reduction in postprandial glucose excursion and prolongation of satiety: possible explanation of the long-term effects of whole grain Salba (Salvia Hispanica L.).

Despite strong correlations linking whole-grain consumption to reductions in heart disease, the physiological mechanisms involved remain ambiguous. We assessed whether Salba (Salvia Hispanica L.) whole grain reduces postprandial glycemia in healthy subjects, as a possible explanation for its cardioprotective effects observed in individuals with diabetes. The study used acute, randomized, double-blind, controlled design in which 11 healthy individuals (6 males and 5 females; body mass index 22.3±2.8 kg/m2) received 0, 7, 15 or 24 g of Salba baked into white bread. Capillary samples and appetite ratings were collected over 2 h after consumption. A dose-response reduction in postprandial glycemia (P=0.002, r2=0.203) was observed with all three doses of Salba, significantly decreasing incremental areas under the curve (iAUCs) and time point-specific blood glucose (P<0.05). Appetite ratings were decreased at 60 min after high, 90 min after high and intermediate and at 120 min after all treatments (P<0.05). Decrease in postprandial glycemia provides a potential explanation for improvements in blood pressure, coagulation and inflammatory markers previously observed after 12-week Salba supplementation in type II diabetes.

The effect of ginseng (the genus panax) on glycemic control: a systematic review and meta-analysis of randomized controlled clinical trials.

Importance Despite the widespread use of ginseng in the management of diabetes, supporting evidence of its anti-hyperglycemic efficacy is limited, necessitating the need for evidence-based recommendations for the potential inclusion of ginseng in diabetes management. Objective To elucidate the effect of ginseng on glycemic control in a systematic review and meta-analysis of randomized controlled trials in people with and without diabetes. Data sources MEDLINE, EMBASE, CINAHL and the Cochrane Library (through July 3, 2013). Study selection Randomized controlled trials ≥30 days assessing the glycemic effects of ginseng in people with and without diabetes. Data extraction Relevant data were extracted by 2 independent reviewers. Discrepancies were resolved by consensus. The Heyland Methodological Quality Score and the Cochrane risk of bias tool were used to assess study quality and risk of bias respectively. Data synthesis Sixteen trials were included, in which 16 fasting blood glucose (n = 770), 10 fasting plasma insulin (n = 349), 9 glycated hemoglobin (n = 264), and 7 homeostasis model assessment of insulin resistance (n = 305) comparisons were reported. Ginseng significantly reduced fasting blood glucose compared to control (MD =  −0.31 mmol/L [95% CI: −0.59 to −0.03], P = 0.03). Although there was no significant effect on fasting plasma insulin, glycated hemoglobin, or homeostasis model assessment of insulin resistance, a priori subgroup analyses did show significant reductions in glycated hemoglobin in parallel compared to crossover trials (MD = 0.22% [95%CI: 0.06 to 0.37], P = 0.01). Limitations Most trials were of short duration (67% trials<12wks), and included participants with a relatively good glycemic control (median HbA1c non-diabetes = 5.4% [2 trials]; median HbA1c diabetes = 7.1% [7 trials]). Conclusions Ginseng modestly yet significantly improved fasting blood glucose in people with and without diabetes. In order to address the uncertainty in our effect estimates and provide better assessments of ginsengs anti-diabetic efficacy, larger and longer randomized controlled trials using standardized ginseng preparations are warranted. Trial Registration ClinicalTrials.gov NCT01841229

Effects of Korean Red Ginseng (Panax ginseng C.A. Mayer) and Its Isolated Ginsenosides and Polysaccharides on Arterial Stiffness in Healthy Individuals

BACKGROUND Preclinical studies indicate a role of Korean red ginseng (KRG) in the modulation of vascular function; however, clinical evidence is scarce. Therefore, the objective of this study was to investigate the effect of KRG root on peripheral blood pressure (BP) and augmentation index (AI), an emerging method to assess cardiovascular risk beyond conventional BP measurements. Furthermore, in an attempt to elucidate which of the major components of KRG is responsible for these effects, the ginsenoside and polysaccharide fractions isolated from the same KRG root were also investigated. METHODS The study was designed as an acute randomized, controlled, double blind, crossover trial. A total of 17 healthy fasted individuals (gender: 9 males:8 females, age: 30 +/- 9 years, body mass index: 25 +/- 3 kg/m(2), systolic BP (SBP): 110 +/- 10.1, diastolic BP (DBP): 65 +/- 7 mm Hg) received, on separate occasions, four treatments consisting of: 3 g of either placebo, KRG root, or a KRG root bioequivalent dose of ginsenoside or polysaccharide fractions. BP and AI were measured by applanation tonometry at baseline, 1, 2, and 3 h post-treatment. RESULTS Compared to placebo, 3 g of KRG significantly lowered radial AI by 4.6% (P = 0.045), whereas the ginsenoside fraction comparably decreased AI by 4.8% (P = 0.057), and no effect was observed with the polysaccharides. There were no differences in BP between treatments. CONCLUSION Although preliminary, this study is the first to demonstrate that KRG may improve arterial stiffness as measured by AI. In addition, it appears that ginsenosides may be the principal pharmacologically active component of the root, rather than the polysaccharide fraction. This study supports the results seen with KRG in the preclinical studies and warrants further investigation on acute and long-term endothelial parameters.

Effect of American ginseng (Panax quinquefolius L.) on arterial stiffness in subjects with type-2 diabetes and concomitant hypertension.

ETHNOPHARMACOLOGICAL RELEVANCE Substantial pre-clinical and some clinical data are available showing that Asian ginseng (Panax ginseng C.A. Meyer) varieties or its particular ginsenosides exert a vasodilatating effect, thus may modulate vascular function. However, the clinical evidence for American ginseng (Panax quinquefolius L.) is scarce. Therefore, this study evaluates the effect of American ginseng (AG) on arterial stiffness, as measured by augmentation index (AI), and blood pressure (BP), in type 2 diabetes patients with concomitant hypertension. MATERIALS AND METHODS Using a double-blind, placebo-controlled, parallel design, each participant was randomized to either the selected AG extract or placebo at daily dose of 3g for 12 weeks as an adjunct to their usual antihypertensive and anti-diabetic therapy (diet and/or medications). AI and BP were measured by applanation tonometry at baseline and after 12 weeks of treatment. RESULTS A total of 64 individuals with well-controlled essential hypertension and type 2 diabetes (gender: 22 M:42 F, age:63 ± 9.3 years, BP: 145 ± 10.8/84 ± 8.0 mmHg, HbA1c: 7.0 ± 1.3%, fasting blood glucose (FBG): 8.1 ± 2.3 mmol/L) completed the study. Compared to placebo, 3g of AG significantly lowered radial AI by 5.3% (P=0.041) and systolic BP by 11.7% (P<0.001) at 12 weeks. No effect was observed with diastolic BP. CONCLUSIONS Addition of AG extract to conventional therapy in diabetes with concomitant hypertension improved arterial stiffness and attenuated systolic BP, thus warrants further investigation on long-term endothelial parameters before recommended as an adjunct treatment.

Korean red ginseng (Panax ginseng C.A. Meyer) root fractions: differential effects on postprandial glycemia in healthy individuals.

ETHNOPHARMACOLOGICAL RELEVANCE Variations in ginsenoside profile may predict the postprandial glucose (PPG)-lowering efficacy of ginseng. Previously we reported differential PPG-lowering effects with two Korean red ginseng (KRG) root. FRACTIONS: body and rootlets, of variable ginsenoside profiles. Whether this effect is reproducible with a different KRG source is unclear. We therefore tested two root fractions from a KRG source with elevated ginsenoside levels to assess its effect on PPG. MATERIALS AND METHODS After a 12-h overnight fast, 13 healthy individuals (6M:7F; age=28 ± 10 y; BMI=24.1 ± 3 kg/m2; FBG=4.77 ± 0.04 mmol/L) randomly received either 3g of KRG-body, rootlets or placebo, on three separate visits. Treatments were consumed 60 min prior to a standard test meal with capillary blood samples at -60, 0, 15, 30, 45, 60, 90 and 120 min. RESULTS The KRGrootlets had>6 fold total ginsensosides than the KRG-body but did not significantly affect PPG. Despite a reduced ginsenoside profile, KRG-body lowered PPG levels at 45, 60, 90 and 120 min during the test (p<0.05), rendering an overall reduction of 27% in incremental area under the glucose curve compared to the control (p<0.05). CONCLUSIONS Comparing the results with a previously studied batch of KRG suggests a potential therapeutic dose range for ginsenosides. This observation should be clinically verified with acute screening and ginsenoside composition analysis.

Effect of Spinach, a High Dietary Nitrate Source, on Arterial Stiffness and Related Hemodynamic Measures: A Randomized, Controlled Trial in Healthy Adults

Diets rich in fruits and vegetables reduce risk of adverse cardiovascular events. However, the constituents responsible for this effect have not been well established. Lately, the attention has been brought to vegetables with high nitrate content with evidence that this might represent a source of vasoprotective nitric oxide. We hypothesized that short-term consumption of spinach, a vegetable having high dietary nitrate content, can affect the arterial waveform indicative of arterial stiffness, as well as central and peripheral blood pressure (BP). Using a placebo-controlled, crossover design, 27 healthy participants were randomly assigned to receive either a high-nitrate (spinach; 845 mg nitrate/day) or low-nitrate soup (asparagus; 0.6 mg nitrate/day) for 7 days with a 1-week washout period. On days 1 and 7, profiles of augmentation index, central, and brachial BP were obtained over 180 min post-consumption in 4 fasted visits. A postprandial reduction in augmentation index was observed at 180 min on high-nitrate compared to low-nitrate intervention (-6.54 ± 9.7% vs. -0.82 ± 8.0%, p = 0.01) on Day 1, and from baseline on Day 7 (-6.93 ± 8.7%, p < 0.001; high vs. low: -2.28 ± 12.5%, p = 0.35), suggesting that the nitrate intervention is not associated with the development of tolerance for at least 7 days of continued supplementation. High vs. low-nitrate intervention also reduced central systolic (-3.39 ± 5.6 mmHg, p = 0.004) and diastolic BP (-2.60 ± 5.8 mmHg, p = 0.028) and brachial systolic BP (-3.48 ± 7.4 mmHg, p = 0.022) at 180 min following 7-day supplementation only. These findings suggest that dietary nitrate from spinach may contribute to beneficial hemodynamic effects of vegetable-rich diets and highlights the potential of developing a targeted dietary approach in the management of elevated BP.

The effect of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for CVD risk reduction: a systematic review and meta-analysis of randomised-controlled trials.

Oats are a rich source of β-glucan, a viscous, soluble fibre recognised for its cholesterol-lowering properties, and are associated with reduced risk of CVD. Our objective was to conduct a systematic review and meta-analysis of randomised-controlled trials (RCT) investigating the cholesterol-lowering potential of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for the risk reduction of CVD. MEDLINE, Embase, CINAHL and Cochrane CENTRAL were searched. We included RCT of ≥3 weeks of follow-up, assessing the effect of diets enriched with oat β-glucan compared with controlled diets on LDL-cholesterol, non-HDL-cholesterol or apoB. Two independent reviewers extracted data and assessed study quality and risk of bias. Data were pooled using the generic inverse-variance method with random effects models and expressed as mean differences with 95 % CI. Heterogeneity was assessed by the Cochrans Q statistic and quantified by the I 2-statistic. In total, fifty-eight trials (n 3974) were included. A median dose of 3·5 g/d of oat β-glucan significantly lowered LDL-cholesterol (-0·19; 95 % CI -0·23, -0·14 mmol/l, P<0·00001), non-HDL-cholesterol (-0·20; 95 % CI -0·26, -0·15 mmol/l, P<0·00001) and apoB (-0·03; 95 % CI -0·05, -0·02 g/l, P<0·0001) compared with control interventions. There was evidence for considerable unexplained heterogeneity in the analysis of LDL-cholesterol (I 2=79 %) and non-HDL-cholesterol (I 2=99 %). Pooled analyses showed that oat β-glucan has a lowering effect on LDL-cholesterol, non-HDL-cholesterol and apoB. Inclusion of oat-containing foods may be a strategy for achieving targets in CVD reduction.

A systematic review and meta-analysis of randomized controlled trials of the effect of barley β-glucan on LDL-C, non-HDL-C and apoB for cardiovascular disease risk reduction i-iv

Background/Objectives:There has been recent interest in barley as a therapeutic food owing to its high content of beta-glucan (β-glucan), a viscous soluble fiber recognized for its cholesterol-lowering properties. The objective of this study was to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the cholesterol-lowering potential of barley β-glucan on low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C) and apolipoprotein B (apoB) for cardiovascular disease (CVD) risk reduction.Methods:MEDLINE, Embase, CINAHL and the Cochrane CENTRAL were searched. We included RCTs of ⩾3-week duration assessing the effect of diets enriched with barley β-glucan compared with controlled diets on LDL-C, non-HDL-C or apoB. Two independent reviewers extracted relevant data and assessed study quality and risk of bias. Data were pooled using the generic inverse-variance method with random effects models and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Heterogeneity was assessed by the Cochran Q-statistic and quantified by the I2 statistic.Results:Fourteen trials (N=615) were included in the final analysis. A median dose of 6.5 and 6.9 g/day of barley β-glucan for a median duration of 4 weeks significantly reduced LDL-C (MD=−0.25 mmol/l (95% CI: −0.30, −0.20)) and non-HDL-C (MD=−0.31 mmol/l (95% CI: −0.39, −0.23)), respectively, with no significant changes to apoB levels, compared with control diets. There was evidence of considerable unexplained heterogeneity in the analysis of non-HDL-C (I2=98%).Conclusions:Pooled analyses show that barley β-glucan has a lowering effect on LDL-C and non-HDL-C. Inclusion of barley-containing foods may be a strategy for achieving targets in CVD risk reduction.

Effect of whole and ground Salba seeds (Salvia Hispanica L.) on postprandial glycemia in healthy volunteers: a randomized controlled, dose-response trial

Objective:Incorporation of seeds into food products may attenuate postprandial glycemia. Whether these should be consumed as whole or in ground form is not known.Subjects/Methods:Using an acute, randomized controlled crossover design, the glycemic response of 13 healthy participants (6M:7F; 25.4±2.6 kg/m2) was studied on nine separate occasions. Test meals consisted of 7, 15 or 24 g of whole or ground Salba baked into white bread, and three control breads matched for energy, and macronutrient profile. Capillary blood samples were collected at fasting and over 2 h post consumption.Results:A significant effect of dose (P=0.04), but no effect of form (P=0.74) or dose-form interaction (P=0.98) was found. No adverse events were reported.Conclusion:This study demonstrates that both ground and whole Salba are equally effective in attenuating blood glucose levels in a dose-dependent manner when incorporated into bread. Flexibility in the use of either the ground or whole seed may increase the ease of incorporation and acceptability as a dietary supplement.