Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials.

BACKGROUND: Increasing nitric oxide bioavailability may induce physiological effects that enhance endurance exercise performance. This review sought to evaluate the performance effects of consuming foods containing compounds that may promote nitric oxide bioavailability. METHODS: Scopus, Web of Science, Ovid Medline, EMBASE and SportDiscus were searched, with included studies assessing endurance performance following consumption of foods containing nitrate, L-arginine, L-citrulline or polyphenols. Random effects meta-analysis was conducted, with subgroup analyses performed based on food sources, sex, fitness, performance test type and supplementation protocol (e.g. duration). RESULTS: One hundred and eighteen studies were included in the meta-analysis, which encompassed 59 polyphenol studies, 56 nitrate studies and three L-citrulline studies. No effect on exercise performance following consumption of foods rich in L-citrulline was identified (SMD=-0.03, p=0.24). Trivial but significant benefits were demonstrated for consumption of nitrate and polyphenol-rich foods (SMD=0.15 and 0.17, respectively, p<0.001), including performance in time-trial, time-to-exhaustion and intermittent-type tests, and following both acute and multiple-day supplementation, but no effect of nitrate or polyphenol consumption was found in females. Among nitrate-rich foods, beneficial effects were seen for beetroot, but not red spinach or Swiss chard and rhubarb. For polyphenol-rich foods, benefits were found for grape, (nitrate-depleted) beetroot, French maritime pine, Montmorency cherry and pomegranate, while no significant effects were evident for New Zealand blackcurrant, cocoa, ginseng, green tea or raisins. Considerable heterogeneity between polyphenol studies may reflect food-specific effects or differences in study designs and subject characteristics. Well-trained males (V̇O2max ≥65 ml.kg.min-1) exhibited small, significant benefits following polyphenol, but not nitrate consumption. CONCLUSION: Foods rich in polyphenols and nitrate provide trivial benefits for endurance exercise performance, although these effects may be food dependent. Highly trained endurance athletes do not appear to benefit from consuming nitrate-rich foods but may benefit from polyphenol consumption. Further research into food sources, dosage and supplementation duration to optimise the ergogenic response to polyphenol consumption is warranted. Further studies should evaluate whether differential sex-based responses to nitrate and polyphenol consumption are attributable to physiological differences or sample size limitations. OTHER: The review protocol was registered on the Open Science Framework ( https://osf.io/u7nsj ) and no funding was provided.

Nutraceuticals: Reviewing their Role in Chronic Disease Prevention and Management.

Over half the adult population in many Western countries consume nutraceuticals because of their purported therapeutic benefits, accessibility and convenience. Several studies have demonstrated that they may also serve as a useful adjunct to pharmaceuticals to better manage chronic conditions or offset negative side effects. Individuals are advised to consult their physician before using nutraceuticals, but this advice is often overlooked. Thus, the community pharmacist plays an increasingly important role in assisting consumers with selecting a nutraceutical that is safe and for which there is evidence of therapeutic efficacy. Therefore, the aim of this review is to summarise the clinical evidence, safety and purported mechanisms of action for selected nutraceuticals in the management of chronic diseases, including obesity, diabetes, hypertension, hypercholesterolemia and inflammatory-based diseases.

The Effect of Anthocyanin-Rich Foods or Extracts on Vascular Function in Adults: A Systematic Review and Meta-Analysis of Randomised Controlled Trials.

Anthocyanins are of interest due to their anti-oxidative and vasodilatory properties. Earlier reviews have shown that berries and other anthocyanin rich foods or extracts can improve vascular health, however the effect of anthocyanins on vascular function has not yet been reviewed. To address this gap in the literature, we conducted a systematic review and meta-analysis of randomised-controlled trials examining anthocyanin-rich foods or extracts on measures of vascular reactivity and/or stiffness in adults. Data from 24 studies were pooled as standardized mean difference (SMD) with 95% confidence intervals (CI). Anthocyanin consumption significantly improved flow-mediated dilation (FMD) following acute (SMD: 3.92%, 95% CI: 1.47, 6.38, p = 0.002; I² = 91.8%) and chronic supplementation (SMD: 0.84%, 95% CI: 0.55, 1.12, p = 0.000; I² = 62.5%). Pulse wave velocity was improved following acute supplementation only (SMD: -1.27 m/s, 95% CI: -1.96, -0.58, p = 0.000; I² = 17.8%). These results support the findings of previous reviews that anthocyanin rich foods or extracts may indeed improve vascular health, particularly with respect to vascular reactivity measured by FMD. More research is required to determine the optimal dosage, and the long-term effects of consumption.

Paucity of evidence for a relationship between long-chain omega-3 fatty acid intake and chronic obstructive pulmonary disease: a systematic review.

CONTEXT: The anti-inflammatory activity of long-chain n-3 polyunsaturated fatty acids (PUFAs) has been established in several chronic inflammatory diseases but has yet to be demonstrated in inflammatory lung diseases such as chronic obstructive pulmonary disease (COPD). OBJECTIVE: The aim of this systematic review was to investigate, using PRISMA guidelines, the relationship between the intake of long-chain n-3 PUFAs and the prevalence, severity, and health outcomes of COPD. DATA SOURCES: Eight health databases and the World Health Organization's international clinical trial registry were searched for relevant studies. STUDY SELECTION: Experimental or observational studies that were published in English and that assessed long-chain n-3 PUFA intake (by determining habitual consumption and/or tissue levels) in adults with COPD were included. DATA EXTRACTION: Publication demographics, participant characteristics, type of intervention or exposure, long-chain n-3 PUFA intake, pulmonary function, COPD mortality, and COPD severity were independently extracted from each article by 2 authors using a prospectively designed data extraction tool. DATA SYNTHESIS: All 11 of the studies included in the review were observational. Approximately equal numbers of studies reported significant (n = 6, 5 inverse) relationships or no significant relationships (n = 5) between either consumption of long-chain n-3 PUFAs or levels of long-chain n-3 PUFAS in tissue and a COPD outcome. CONCLUSIONS: Current evidence of a relationship between long-chain n-3 PUFA intake and COPD is limited and conflicting, with studies having wide methodological variation. REGISTRATION NUMBER: PROSPERO 2013:CRD42013004085.

Feasibility of ω-3 fatty acid supplementation as an adjunct therapy for people with chronic obstructive pulmonary disease: study protocol for a randomized controlled trial.

BACKGROUND: There is evidence to support the use of supplementation with long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) from oily fish or fish oil for the treatment of various inflammatory diseases such as rheumatoid arthritis. Chronic obstructive pulmonary disease (COPD) is a progressive, terminal disease characterized by persistent airflow limitation, lung and systemic inflammation. To date, one randomized controlled trial has been published that assessed the efficacy of LCn-3PUFA in people with this condition. The aim of this article is to discuss the feasibility of conducting a trial to evaluate fish oil supplementation as adjunct therapy in people with COPD. METHODS/DESIGN: A 16-week parallel, double-blind, randomized, placebo-controlled dietary supplementation trial will be evaluated. Forty participants meeting spirometric and clinical criteria for COPD will be recruited from metropolitan Adelaide, South Australia. Participants will be randomized by minimization, based on a score derived from the modified Medical Research Council Scale for breathlessness, to receive 6 g/day of fish oil (approximately 3.6 g/day of LCn-3PUFA), or placebo (6 g/day of corn oil) capsules. Feasibility outcomes (recruitment, retention, supplement adherence, and time lost to exacerbation) and scientific outcomes (effect size and estimates of variance for inflammatory biomarkers, incorporation of LCn-3PUFA into erythrocytes, small airways function, dyspnea and functional exercise capacity) will be assessed pre- and post-intervention. Key feasibility criteria include recruitment of 40 participants in 52 weeks, 75% participant retention rate, 2% increase in the proportion of long-chain omega-3 fatty acids in erythrocytes, and a positive moderate effect size in at least three efficacy measures. DISCUSSION: There are a number of challenges in designing supplementation intervention studies with this population. These include the lack of prior data from which to select appropriate primary outcomes or to estimate effect sizes, and the feasibility of continuous supplementation in a population characterized by multiple comorbidities and a high likelihood of exacerbations, potentially requiring hospitalization or change in medication. Upon completion of this protocol, feasibility outcomes will guide the direction of future multicentre dietary interventions in this population. TRIAL REGISTRATION: Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12612000158864.

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.

Lifestyle approaches and dietary strategies to lower LDL-cholesterol and triglycerides and raise HDL-cholesterol.

This article discusses specific dietary factors as well as dietary patterns that affect the major coronary heart disease (CHD) lipid risk factors (ie, LDL-C, HDL-C, and TG). Based on a very large evidence base, it is clear that diet and lifestyle practices can markedly affect these major CHD lipid risk factors, and consequently decrease CHD risk substantively.

Docosahexaenoic acid-rich fish oil improves heart rate variability and heart rate responses to exercise in overweight adults.

Dietary fish oil supplementation and regular physical activity can improve outcomes in patients with established CVD. Exercise has been shown to improve heart rate variability (HRV), a predictor of cardiac death, but whether fish oil benefits HRV is controversial. Obese adults at risk of future coronary disease have impaired HRV and may benefit from these interventions. We evaluated the effect of DHA-rich tuna fish oil supplementation with and without regular exercise on HRV in sedentary, overweight adults with risk factors for coronary disease. In a randomised, double-blind, parallel comparison, sixty-five volunteers consumed 6 g fish oil/d (DHA 1.56 g/d, EPA 0.36 g/d) or sunflower-seed oil (placebo) for 12 weeks. Half of each oil group also undertook regular moderate physical activity (3 d/week for 45 min, at 75 % of age-predicted maximal heart rate (HR)). Resting HR and the HR response to submaximal exercise were measured at weeks 0, 6 and 12. In forty-six subjects, HRV was also assessed by power spectrum analysis of 20 min electrocardiogram recordings taken supine at baseline and 12 weeks. Fish oil supplementation improved HRV by increasing high-frequency power, representing parasympathetic activity, compared with placebo (P = 0.01; oil x time interaction). It also reduced HR at rest and during submaximal exercise (P = 0.008; oil x time interaction). There were no significant fish oil x exercise interactions. Dietary supplementation with DHA-rich fish oil reduced HR and modulated HRV in keeping with an improved parasympathetic-sympathetic balance in overweight adults with risk factors for future coronary disease.

Can EGCG reduce abdominal fat in obese subjects?

OBJECTIVE: To evaluate metabolic effects of epigallocatechin gallate (EGCG) supplementation when combined with a program of regular aerobic exercise in overweight/obese post-menopausal women. METHODS: Thirty-eight overweight or obese postmenopausal women exercised at moderate intensity, viz. walking three times per week for 45 min at 75% of age-predicted maximum heart rate (HR), and took a 150 mg capsule of EGCG (Teavigo) or placebo (lactose) twice daily for 12 weeks. Blood parameters (lipids, glucose and insulin), blood pressure, heart rate, arterial function and anthropometry were assessed at 0, 6 and 12 wk. At wk 0 and 12, body composition was assessed by dual energy X-ray absorptiometry (DXA) and abdominal fat was assessed by DXA and computed tomography (CT). RESULTS: Waist circumference (p < 0.01), total body fat (p < 0.02), abdominal fat (by DXA) (p < 0.01) and intra abdominal adipose tissue (by CT) (p < 0.01) were reduced in both treatment groups, with no difference between placebo and Teavigo. Teavigo significantly decreased resting HR (p < 0.01) and reduced plasma glucose in subjects with impaired glucose tolerance (p < 0.05). CONCLUSIONS: Moderate consumption of EGCG can improve the health status of overweight individuals undergoing regular exercise by reducing HR and plasma glucose concentrations. Loss of body fat, however, may require a higher intake of EGCG, other catechins or addition of metabolic stimulants.

Combining fish-oil supplements with regular aerobic exercise improves body composition and cardiovascular disease risk factors.

BACKGROUND: Regular exercise and consuming long-chain n-3 fatty acids (FAs) from fish or fish oil can independently improve cardiovascular and metabolic health, but combining these lifestyle modifications may be more effective than either treatment alone. OBJECTIVE: We examined the individual and combined effects of n-3 FA supplements and regular exercise on body composition and cardiovascular health. DESIGN: Overweight volunteers [body mass index (BMI; in kg/m(2)): >25] with high blood pressure, cholesterol, or triacylglycerols were randomly assigned to one of the following interventions: fish oil (FO), FO and exercise (FOX), sunflower oil (SO; control), or SO and exercise (SOX). Subjects consumed 6 g tuna FO/d ( approximately 1.9 g n-3 FA) or 6 g SO/d. The exercise groups walked 3 d/wk for 45 min at 75% age-predicted maximal heart rate. Plasma lipids, blood pressure, and arterial function were assessed at 0, 6, and 12 wk. Body composition was assessed by dual-energy X-ray absorptiometry at 0 and 12 wk only. RESULTS: FO supplementation lowered triacylglycerols, increased HDL cholesterol, and improved endothelium-dependent arterial vasodilation (P<0.05). Exercise improved arterial compliance (P<0.05). Both fish oil and exercise independently reduced body fat (P<0.05). CONCLUSIONS: FO supplements and regular exercise both reduce body fat and improve cardiovascular and metabolic health. Increasing intake of n-3 FAs could be a useful adjunct to exercise programs aimed at improving body composition and decreasing cardiovascular disease risk.

n-3 Fatty acid supplementation and regular moderate exercise: differential effects of a combined intervention on neutrophil function.

CVD is associated with a cellular inflammatory/immune response. n-3 PUFA and moderate aerobic exercise independently alter cytokine production and leucocyte function. There is limited evidence for the combined effect of these treatments on immune function, particularly in patients with risk factors for CVD. We hypothesised that exercise would enhance the anti-inflammatory effects of n-3 PUFA. In a randomised, placebo-controlled study, fifty volunteers were allocated double-blind to consume either sunflower oil (6 g/d, placebo) or DHA-rich fish oil (6 g/d; about 2 g n-3 PUFA; 1.6 g DHA /d) for 12 weeks. Volunteers were further randomised to undertake regular exercise (walking 3 d/week for 45 min at 75 % of maximum heart rate) or maintain their usual physical activity for 12 weeks. Immune functions were assessed in blood taken initially and after 12 weeks. There was no effect on cytokine production by T cells and monocytes. Superoxide anion production from stimulated blood neutrophils was decreased by fish oil (19.5 (sem 8.5) %, P = 0.016) but not by exercise, and this change was negatively correlated with the incorporation of DHA into erythrocytes (r-0.385, P = 0.047). Participation in regular exercise maintained neutrophil bactericidal activity, which decreased in non-exercising subjects (2.9 (sem 0.7) %, P = 0.013). Neutrophil chemotaxis and adherence were not significantly affected by exercise, oil, or the combination of the two. Thus the combination of moderate exercise and fish-oil supplementation, which reduces cardiovascular risk, may also help to counteract inflammation.