Does the evidence support a relationship between higher levels of nut consumption, lower risk of depression, and better mood state in the general population? A systematic review.

CONTEXT: Dietary patterns play a key role in mental health, depression, and mood state. However, the evidence concerning specific foods highly recommended for mental health, such as nuts, has not yet been synthesized. OBJECTIVE: The objective of this review was to synthesize the evidence for a relationship between higher levels of nut consumption, lower risk of depression, and better mood state in the general population. DATA SOURCES: The MEDLINE, Scopus, Cochrane Central, Web of Science, and PsycInfo databases were systematically searched from each database's inception to March 2021. DATA EXTRACTION: Randomized clinical trials (RCTs) and observational studies exploring the association between nut consumption, level of depression, and mood state in the general population were included. The quality of the studies was measured through the Joanna Briggs Institute tool (cross-sectional studies), the NIH Quality Assessment Tool (cohort studies), and the Cochrane Risk-of-Bias tool (RCTs). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. DATA ANALYSIS: A total of 10 studies involving 66 418 individuals were included, of which 3 were cross-sectional, 3 were cohort studies, and 4 were RCTs. In studies concerned with depression (n = 6 studies), a higher level of nut consumption was associated with a lower risk of depression in 2 cross-sectional studies and 1 cohort study, while a similar but nonsignificant association was found in another cohort and in two RCTs. In studies concerned with mood state (n = 4), 1 cohort study reported an association between higher nut consumption and significant improvement in mood state, whereas (nonsignificant) associations between higher nut consumption and increased negative feelings were reported in a cross-sectional study and two RCTs. CONCLUSION: Despite the small number of studies and the limitations related to them, such as reverse causation bias, overall, the available literature suggests that higher nut consumption could be associated with a lower risk of depression, fewer depressive symptoms, and better mood state in the general population. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42021241070.

Immediate effect of high-intensity exercise on brain-derived neurotrophic factor in healthy young adults: A systematic review and meta-analysis.

BACKGROUND: Although brain-derived neurotrophic factor (BDNF) has been identified as a molecular biomarker of the neurophysiological effects induced by exercise, the acute effects of high-intensity exercise (HIE) on BDNF levels are inconclusive. This study aims to estimate the immediate effects of HIE on BDNF levels in healthy young adults. METHODS: A systematic search was conducted in the MEDLINE, Scopus, Cochrane CENTRAL, and SPORTDiscuss databases up to December 2020. Randomized controlled trials (RCTs) and non-RCTs reporting pre-post changes in serum or plasma BDNF after an acute intervention of HIE compared to a control condition were included. Pooled effect sizes (p-ESs) and 95% confidence intervals (95%CIs) were calculated for RCTs using a random effects model with Stata/SE (Version 15.0; StataCorp., College Station, TX, USA). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. PROPERO registration number: CRD42020221047. RESULTS: A total of 22 studies with 552 individuals (age range: 20-31 years; 59.1% male) were included. The meta-analysis included 10 RCTs that reported valid outcome data. Higher BDNF levels were observed when HIE interventions were compared with non-exercise (p-ES = 0.55, 95%CI: 0.12-0.98; I2 = 25.7%; n = 4 studies) and light-intensity exercise (p-ES = 0.78, 95%CI: 0.15-1.40; I2 = 52.4%; n = 3 studies) but not moderate-intensity exercise (p-ES = 0.93, 95%CI: -0.16 to 2.02; I2 = 88.5%; n = 4 studies) conditions. CONCLUSION: In comparison to non-exercise or light-intensity exercises, an immediate increase in BDNF levels may occur when young adults perform HIE. Given the benefits obtained maximizing circulating BDNF when performing HIE and its potential effects on brain health, our findings suggest that HIE could be recommended by clinicians as a useful exercise strategy to healthy adults.

Nut consumption, body weight, and adiposity in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials.

CONTEXT: It seems that nut consumption does not lead to weight gain in the general population. However, fewer studies have explored this relationship in individuals with type 2 diabetes (T2D). PURPOSE: To synthesize evidence on the effects of nut (specifically, tree nuts and peanuts) consumption on adiposity-related measures in individuals diagnosed with T2D. DATA SOURCES AND STUDY SELECTION: Four databases were searched up to December 31, 2020. Randomized controlled trials that examined the effects of nut consumption vs a control diet on body weight, body mass index, waist circumference, and percent body fat were included. DATA EXTRACTION: The pooled effect sizes (p-ESs) and 95%CIs of nut consumption were estimated using random effects models. DATA SYNTHESIS: A total of 15 randomized controlled trials including 899 individuals were included. No significant effects of nut-enriched interventions were found for body weight (p-ES = -0.04; 95%CI: -0.16 to 0.08), body mass index (p-ES = -0.05; 95%CI: -0.17 to 0.08), waist circumference (p-ES = -0.02; 95%CI: -0.20 to 0.15), or percent body fat (p-ES = -0.03; 95%CI: -0.28 to 0.21). CONCLUSION: Nut consumption has no effect, positive or negative, on weight or adiposity parameters in people with T2D.

The Relationship of Tree Nuts and Peanuts with Adiposity Parameters: A Systematic Review and Network Meta-Analysis.

The network meta-analysis and systematic review conducted aim to comparatively assess the effects of tree nuts and peanuts on body weight (BW), body mass index (BMI), waist circumference (WC), and body fat percentage (BF%). A systematic search up to 31 December 2020 was performed. A random-effects network meta-analysis was conducted following the PRISMA-NMA statement. A total of 105 randomized controlled trials (RCTs) with measures of BW (n = 6768 participants), BMI (n = 2918), WC (n = 5045), and BF% (n = 1226) were included. The transitivity assumption was met based on baseline characteristics. In the comparisons of nut consumption versus a control diet, there was no significant increase observed in any of the adiposity-related measures examined except for hazelnut-enriched diets, which raised WC. Moreover, almond-enriched diets significantly reduced WC compared to the control diet and to the pistachio-, mixed nuts-, and hazelnut-enriched diets. In subgroup analyses with only RCTs, designed to assess whether nut consumption affected weight loss, almonds were associated with reduced BMI and walnuts with reduced %BF. The evidence supports that: (1) tree nut and peanut consumption do not influence adiposity, and (2) compared to a control diet, the consumption of almond-enriched diets was associated with a reduced waist circumference.

Relationship between exclusive breastfeeding and brain-derived neurotrophic factor in children.

OBJECTIVE: A positive relationship between breastfeeding and brain-derived neurotrophic factor (BDNF) in infants has been suggested due to the presence of BDNF in human milk. This study aimed to determine the relationship between exclusive breastfeeding and BDNF serum levels in Spanish schoolchildren. METHODS: A cross-sectional analysis including 202 schoolchildren, aged eight to 11 years, from Cuenca, Spain, was conducted. Information on sociodemographic and anthropometric variables, sexual maturation, birth weight and exclusive breastfeeding ('no exclusive breastfeeding', and exclusive breastfeeding for ≤6 and >6 months), and BDNF serum levels using an ELISA method were obtained. Covariance analyses (ANCOVA) were conducted to examine the relationship between serological BDNF and exclusive breastfeeding after controlling for potential confounders. RESULTS: ANCOVA models showed no significant differences in BDNF levels between children who were exclusively breastfed for more than six months versus those who were not (p > 0.05). No significant differences were observed by age group (eight to nine years versus 10 to 11 years; p > 0.05). Additionally, no clear negative trend in BDNF serum levels according to sexual maturation categories was found (p > 0.05). CONCLUSION: These findings suggest that exclusive breastfeeding does not have a significant positive association on BDNF from eight to 11 years, since children who were exclusively breastfed did not have significantly higher BDNF levels than those who were not exclusively breastfed. Likewise, BDNF levels were not found to be negatively affected by hormonal development. Future research should examine the influence of exclusive breastfeeding on BDNF over the different developmental stages.