SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Applied physiology, nutrition, and metabolism = Physiologie appliquée, nutrition et métabolisme

50

Protein is an essential component of a healthy diet and is a focus of research programs seeking to optimize health at all stages of life. The focus on protein as a nutrient often centers on its thermogenic and satiating effect, and when included as part of a healthy diet, its potential to preserve lean body mass. A growing body of literature, including stable isotope based studies and longer term dietary interventions, suggests that current dietary protein recommendations may not be sufficient to promote optimal muscle health in all populations. A protein intake moderately higher than current recommendations has been widely endorsed by many experts and working groups and may provide health benefits for aging populations. Further, consuming moderate amounts of high-quality protein at each meal may optimally stimulate 24-h muscle protein synthesis and may provide a dietary platform that favors the maintenance of muscle mass and function while promoting successful weight management in overweight and obese individuals. Dietary protein has the potential to serve as a key nutrient for many health outcomes and benefits might be increased when combined with adequate physical activity. Future studies should focus on confirming these health benefits from dietary protein with long-term randomized controlled studies.

Concepts: Health, Metabolism, Nutrition, Energy, Obesity, Physical exercise, Adipose tissue, Healthy diet

49

Observational studies support that dairy product intake is associated with a reduced risk of developing type 2 diabetes; however, several clinical studies report conflicting results on the association between dairy product consumption and metabolic parameters. The aim of this study was to determine associations between dairy product consumption and metabolic profile. Dietary data, using a validated food frequency questionnaire, and fasting blood samples were collected from 233 French Canadians. Plasma phospholipid (PL) fatty acids (FA) concentrations were determined by gas chromatography. Subjects consumed 2.5 ± 1.4 portions of dairy products daily, including 1.6 ± 1.3 portions of low-fat (LF) and 0.90 ± 0.70 portions of high-fat (HF) dairy products. Trans-palmitoleic acid level in plasma PL was related to HF dairy consumption (r = 0.15; p = 0.04). Total (r = -0.21; p = 0.001) and LF dairy (r = -0.20; p = 0.003) intakes were inversely correlated with fasting plasma glucose level. Total dairy intake was inversely associated to systolic blood pressure (r = -0.17; p = 0.008) and diastolic blood pressure (r = -0.14; p = 0.03). LF dairy intake was also inversely correlated with systolic blood pressure (r = -0.17; p = 0.009). Total dairy intake was correlated with plasma C-reactive protein (CRP) (r = 0.15; p = 0.03). No association was found between HF dairy consumption and the risk factors studied. In conclusion, dairy intake is inversely associated with glycaemia and blood pressure; yet, it may modify CRP levels. Moreover, trans-palmitoleic FA levels in plasma PL may be potentially used to assess full-fat dairy consumption.

Concepts: Protein, Nutrition, Blood, Hypertension, Blood pressure, Artery, C-reactive protein, Systole

47

The hypothesis that oral supplementation with virgin coconut oil (Cocos nucifera L.) and exercise training would improve impaired baroreflex sensitivity (BRS) and reduce oxidative stress in spontaneously hypertensive rats (SHR) was tested. Adult male SHR and Wistar Kyoto rats (WKY) were divided into 5 groups: WKY + saline (n = 8); SHR + saline (n = 8); SHR + coconut oil (2 mL·day(-1), n = 8); SHR + trained (n = 8); and SHR + trained + coconut oil (n = 8). Mean arterial pressure (MAP) was recorded and BRS was tested using phenylephrine (8 μg/kg, intravenous) and sodium nitroprusside (25 μg·kg(-1), intravenous). Oxidative stress was measured using dihydroethidium in heart and aorta. SHR + saline, SHR + coconut oil, and SHR + trained group showed higher MAP compared with WKY + saline (175 ± 6, 148 ± 6, 147 ± 7 vs. 113 ± 2 mm Hg; p < 0.05). SHR + coconut oil, SHR + trained group, and SHR + trained + coconut oil groups presented lower MAP compared with SHR + saline group (148 ± 6, 147 ± 7, 134 ± 8 vs. 175 ± 6 mm Hg; p < 0.05). Coconut oil combined with exercise training improved BRS in SHR compared with SHR + saline group (-2.47 ± 0.3 vs. -1.39 ± 0.09 beats·min(-1)·mm Hg(-1); p < 0.05). SHR + saline group showed higher superoxide levels when compared with WKY + saline (774 ± 31 vs. 634 ± 19 arbitrary units (AU), respectively; p < 0.05). SHR + trained + coconut oil group presented reduced oxidative stress compared with SHR + saline in heart (622 ± 16 vs. 774 ± 31 AU, p < 0.05). In aorta, coconut oil reduced oxidative stress in SHR compared with SHR + saline group (454 ± 33 vs. 689 ± 29 AU, p < 0.05). Oral supplementation with coconut oil combined with exercise training improved impaired BRS and reduced oxidative stress in SHR.

Concepts: Better, Hypertension, Blood pressure, Cortisol, Saturated fat, Coconut, Coconuts, Coconut oil

40

The rates of overweight and obesity are rising in Canada and worldwide, and there is a need for effective methods for weight loss and weight maintenance to empower individuals to make changes. The purpose of this systematic review was to examine the evidence available for successful diet strategies for weight loss and weight maintenance among adults. A search was conducted of the following databases: CAB Abstracts, Central Register of Controlled Trials, EMBASE, MEDLINE, Food Science and Technology Abstracts, and Web of Knowledge. The studies investigated had participants who were overweight or obese and between 18 and 65 years of age. A successful study was defined as one that reported an intervention that created ≥5% weight loss from baseline and a maintenance phase during which the ≥5% weight loss was maintained from baseline to 12 months. After exclusions, the search resulted in 67 papers. Overall, for significant safe weight loss, an energy deficit was required, which was commonly achieved by reduced fat intake. Increased dietary fibre was also a component of 21% of successful interventions. Physical activity was included in 88% of successful interventions, and behaviour training such as self-monitoring was part of 92% of successful interventions. The same combination of energy and fat restriction, regular physical activity, and behavioural strategies was also required for successful weight maintenance. This review confirmed previous knowledge about weight loss and weight maintenance in adults. A comprehensive approach, including reduced dietary intake, regular physical activity, and behavioural strategies, is warranted and is supported by the research evidence.

Concepts: Cancer, Nutrition, Obesity, Physical exercise, Overweight, Adipose tissue, Weight loss, Dieting

34

This study examined the effects of an acute bout of brief, high-intensity interval exercise on off-task classroom behaviour in primary school students. A grade 4 class (n = 24) and a grade 2 class (n = 20) were exposed to either a no-activity break or an active break that consisted of “FUNtervals”, a high-intensity interval protocol, on alternating days for 3 weeks. No-activity days consisted of a 10-min inactive break while FUNterval days consisted of a 4-min FUNterval completed within a 10-min break from regular class activities. Off-task behaviour was observed for 50 min after each no-activity/FUNterval break, with the amount of time students spent off-task (motor, passive, and verbal behaviour) being recorded. When comparing no-activity breaks with FUNtervals the grade 4 class demonstrated reductions in both passive (no activity = 29% ± 13% vs. FUNterval = 25% ± 13%, p < 0.05, effect size (ES) = 0.31) and motor (no activity = 31% ± 16% vs. FUNterval = 24% ± 13%, p < 0.01, ES = 0.48) off-task behaviour following FUNtervals. Similarly, in the grade 2 class, passive (no activity = 23% ± 14% vs. FUNterval = 14% ± 10%, p < 0.01, ES = 0.74), verbal (no activity = 8% ± 8% vs. FUNterval = 5% ± 5%, p < 0.05, ES = 0.45), and motor (no activity = 29% ± 17% vs. FUNterval = 14% ± 10%, p < 0.01, ES = 1.076) off-task behaviours were reduced following FUNtervals. In both classrooms the effects of physical activity were greatest in those students demonstrating the highest rates of off-task behaviour on no-activity days. These data demonstrate that very brief high-intensity bouts of exercise can improve off-task behaviour in grade 2 and 4 students, particularly in students with high rates of such behaviour.

Concepts: Grade, Physical exercise, Demonstration, High school, Primary school, Primary education, Gymnasium, Classroom

32

The extent to which a high intake of saturated fat (SFA) increases the risk of cardiovascular disease (CVD) has become a highly controversial topic. Dietary SFA primarily raises low-density lipoprotein cholesterol, while having a relatively neutral impact on other key CVD risk factors. Recent epidemiological data also challenge the concept that SFA increases the risk of CVD. This short review provides arguments for the urgency to re-assess the association between dietary SFA and CVD risk in light of recent data on the subject.

Concepts: Cholesterol, Epidemiology, Nutrition, Atherosclerosis, Cardiovascular disease, Low-density lipoprotein, Atheroma, Lipoprotein

31

The impact of Montmorency tart cherry (Prunus cerasus L.) concentrate (MC) on physiological indices and functional performance was examined following a bout of high-intensity stochastic cycling. Trained cyclists (n = 16) were equally divided into 2 groups (MC or isoenergetic placebo (PLA)) and consumed 30 mL of supplement, twice per day for 8 consecutive days. On the fifth day of supplementation, participants completed a 109-min cycling trial designed to replicate road race demands. Functional performance (maximum voluntary isometric contraction (MVIC), cycling efficiency, 6-s peak cycling power) and delayed onset muscle soreness were assessed at baseline, 24, 48, and 72 h post-trial. Blood samples collected at baseline, immediately pre- and post-trial, and at 1, 3, 5, 24, 48, and 72 h post-trial were analysed for indices of inflammation (interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor alpha, high-sensitivity C-reactive protein (hsCRP)), oxidative stress (lipid hydroperoxides), and muscle damage (creatine kinase). MVIC (P < 0.05) did not decline in the MC group (vs. PLA) across the 72-h post-trial period and economy (P < 0.05) was improved in the MC group at 24 h. IL-6 (P < 0.001) and hsCRP (P < 0.05) responses to the trial were attenuated with MC (vs. PLA). No other blood markers were significantly different between MC and PLA groups. The results of the study suggest that Montmorency cherry concentrate can be an efficacious functional food for accelerating recovery and reducing exercise-induced inflammation following strenuous cycling exercise.

Concepts: Inflammation, C-reactive protein, Tumor necrosis factor-alpha, Cherry, Bodybuilding, Cherries, Montmorency cherry, Sour cherry

28

Caffeine is a substance that has been used in our society for generations, primarily for its effects on the central nervous system that causes wakefulness. Caffeine supplementation has become increasingly more popular as an ergogenic aid for athletes and considerable scientific evidence supports its effectiveness. Because of their potential to alter energy metabolism, the effects of coffee and caffeine on glucose metabolism in diabetes have also been studied both epidemiologically and experimentally. Predominantly targeting the adenosine receptors, caffeine causes alterations in glucose homeostasis by decreasing glucose uptake into skeletal muscle, thereby causing elevations in blood glucose concentration. Caffeine intake has also been proposed to increase symptomatic warning signs of hypoglycemia in patients with type 1 diabetes and elevate blood glucose levels in patients with type 2 diabetes. Other effects include potential increases in glucose counterregulatory hormones such as epinephrine, which can also decrease peripheral glucose disposal. Despite these established physiological effects, increased coffee intake has been associated with reduced risk of developing type 2 diabetes in large-scale epidemiological studies. This review paper highlights the known effects of caffeine on glucose homeostasis and diabetes metabolism during rest and exercise.

Concepts: Metabolism, Insulin, Diabetes mellitus type 2, Diabetes mellitus, Hormone, Diabetes mellitus type 1, Blood sugar, Caffeine

28

The purpose of this study was to analyze the effect of recovery type (passive vs. active) during prolonged intermittent exercises on the blood lactate concentration (MLSS) and work rate (MLSS(wint)) at maximal lactate steady state. Nineteen male trained cyclists were divided into 2 groups for the determination of MLSS(wint) using passive (maximal oxygen uptake = 58.1 ± 3.5 mL·kg(-1)·min(-1); N = 9) or active recovery (maximal oxygen uptake = 60.3 ± 9.0 mL·kg(-1)·min(-1); N = 10). They performed the following tests, on different days, on a cycle ergometer: (i) incremental test until exhaustion to determine maximal oxygen uptake; (ii) 2 to 3 continuous submaximal constant work rate tests (CWRT) for the determination of the work rate at continuous maximal lactate steady state (MLSS(wcont)); and (iii) 2 to 3 intermittent submaximal CWRT (7 × 4 min and 1 × 2 min, with 2-min recovery) with either passive or active recovery for the determination of MLSS(wint). MLSS(wint) was significantly higher when compared with MLSS(wcont) for both passive recovery (294.7 ± 32.2 vs. 258.7 ± 24.5 W, respectively) and active recovery groups (300.5 ± 23.9 vs. 273.2 ± 21.5 W, respectively). The percentage increments in MLSS(wint) were similar between conditions (passive = 13% vs. active = 10%). MLSS (mmol·L(-1)) was not significantly different between MLSS(wcont) and MLSS(wint) for either passive recovery (4.50 ± 2.10 vs. 5.61 ± 1.78, respectively) and active recovery (4.06 ± 1.49 vs. 4.91 ± 1.91, respectively) conditions. We can conclude that using a work/rest ratio of 2:1, MLSS(wint) was ∼10%-13% higher than MLSS(wcont), irrespective of the recovery type performed during prolonged intermittent exercises.

Concepts: Thermodynamics, Steady state, The Work, VO2 max

27

This study evaluates the effect of wild blueberry (WB) consumption on the biomechanical properties of the aorta in the obese Zucker rat (OZR), a model of the metabolic syndrome. Thirty-six OZRs and 36 lean controls (lean Zucker rats) were placed either on a WB-enriched or a control © diet for 8 weeks. Phenylephrine (Phe)-mediated vasoconstriction and acetylcholine (Ach)-mediated vasorelaxation in the aortic vessel were investigated, as well as the contribution of the nitric oxide synthase and cyclooxygenase (COX) pathways in each of the above responses by using specific inhibitors. Obese Zucker rats exhibited a reduced vasocontstrictor response to Phe and an exaggerated vasorelaxant response to Ach. The WB diet partially restored Phe-induced constrictor responses and attenuated Ach-induced relaxant responses in OZR. Plasma nitric oxide was significantly attenuated (22.1 ± 1.1 μmol·L(-1), WB vs 25.6 ± 1.4 μmol·L(-1), C, p ≤ 0.05) with the WB diet. Thromboxane A2 levels in the aortic effluent were not significantly affected in the WB diet group, while PGI2 concentration significantly increased (766.5 ± 92.2 pg·mg(-1) aorta in the WB vs 571.7 ± 37.8 pg·g(-1) aorta in the C group, p ≤ 0.05). Downregulation of inducible nitric oxide synthase and COX2 expression in the OZR aorta was observed in the WB diet group. In conclusion, WB consumption altered the biomechanical properties of the OZR aorta by partially restoring the impaired Phe-induced constrictor responses and attenuating the exaggerated response to Ach-induced vasorelaxation.

Concepts: Nutrition, Endothelium, Nitric oxide, Vasodilation, Aorta, Nitric oxide synthase