1.
Snacking on Whole Almonds for Six Weeks Increases Heart Rate Variability during Mental Stress in Healthy Adults: A Randomized Controlled Trial.
Dikariyanto, V, Smith, L, Chowienczyk, PJ, Berry, SE, Hall, WL
Nutrients. 2020;(6)
Abstract
Cardiac autonomic regulation can be indirectly measured by heart rate variability (HRV). Low HRV, which can be induced by mental stress, is a predictor of risk of sudden cardiac death. Few studies have investigated cause-and-effect relationships between diet and HRV. Nut consumption is associated with CVD risk reduction, but the impact on HRV, particularly in response to stress, is unclear. Men and women (30-70 y) with above average risk of developing CVD were randomly assigned in a 6-week randomized, controlled, parallel arm trial to consume either whole almond or isocaloric control snacks (20% of daily estimated energy requirement). Control snacks contained the average nutrient profile of UK snacks. Five-minute periods of supine heart rate (HR) and HRV were measured at resting and during mental stress (Stroop color-word test) at baseline and six weeks. High frequency (HF) power, which reflects parasympathetic regulation of HR, was increased following almonds during the mental stress task relative to control (mean difference between groups 124 ms2; 95% CI 11, 237; p = 0.031, n = 105), but other indices were unaffected. Snacking on whole almonds instead of typical snacks may reduce risk of CVD partly by ameliorating the suppression of HRV during periods of mental stress.
2.
Is chocolate consumption associated with health outcomes? An umbrella review of systematic reviews and meta-analyses.
Veronese, N, Demurtas, J, Celotto, S, Caruso, MG, Maggi, S, Bolzetta, F, Firth, J, Smith, L, Schofield, P, Koyanagi, A, et al
Clinical nutrition (Edinburgh, Scotland). 2019;(3):1101-1108
Abstract
BACKGROUND & AIMS The literature regarding the potential health benefits of chocolate consumption are unclear and the epidemiological credibility has not been systematically scrutinized, while the strength of the evidence is undetermined. We therefore aimed to map and grade the diverse health outcomes associated with chocolate consumption using an umbrella review of systematic reviews. METHODS Umbrella review of systematic reviews of observational and intervention studies (randomized placebo-controlled trials, RCTs). For each association, random-effects summary effect size, 95% confidence interval, and 95% prediction interval were estimated. We also assessed heterogeneity, evidence for small-study effect and evidence for excess significance bias. For significant outcomes of the RCTs, the GRADE assessment was furtherly used. RESULTS From 240 articles returned, 10 systematic reviews were included (8 of which included a meta-analysis), including a total of 84 studies (36 prospective observational studies and 48 interventional). Nineteen different outcomes were included. Among observational studies, including a total of 1,061,637 participants, the best available evidence suggests that chocolate consumption is associated with reduced risk of cardiovascular disease (CVD) death (n = 4 studies), acute myocardial infarction (n = 6), stroke (n = 5) and diabetes (n = 6), although this was based on a weak evidence of credibility. Across meta-analyses of intervention studies, chocolate consumption was positively associated with flow-mediated dilatation at 90-150 min (n = 3) and at 2-18 weeks (n = 3), and insulin resistance markers (n = 2). However, using the GRADE assessment, the evidence for these outcomes was low or very low. Data from two systematic reviews, reported that chocolate consumption was not associated with better depressive mood or cognitive function. CONCLUSIONS There is weak evidence to suggest that chocolate consumption may be associated with favorable health outcomes.