Effect of walnut consumption on markers of blood glucose control: a systematic review and meta-analysis

Neale, Elizabeth P.; Guan, Vivienne; Tapsell, Linda C.; Probst, Yasmine

doi:10.1017/s0007114520001415

Cited by 29 publications

(24 citation statements)

References 68 publications

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“…The four studies included for the HOMA-IR outcome also had moderate statistical heterogeneity, but overall did not show an effect of walnut consumption. These findings concur with a recently published systematic review and meta-analysis, which found no significant effects of walnut consumption on HbA1c and HOMA-IR [73]. Likewise, our meta-analyses for the inflammation markers hsCRP, IL-6, TNFA, E-Selectin, sICAM-1 and sVCAM-1 did not reach statistical significance.…”

Section: Discussionsupporting

confidence: 92%

Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis

et al. 2021

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Background: Walnuts contain nutrients that are associated with improved cognitive health. To our knowledge, no review has systematically examined the effects of walnuts on cognitive function and risk for cognitive decline. Objective: To conduct a systematic review and meta-analysis evaluating the effects of walnut intake on cognition-related outcomes and risk-factors for cognitive decline in adults. Methods: Medline V R , Commonwealth Agricultural Bureau, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) and observational studies published until April 2020 on walnut intake, cognition (e.g. cognitive function, stroke, and mood), and selected risk factors for cognitive decline (e.g. glucose homeostasis and inflammation). Risk-of-bias and strength-of-evidence assessments were conducted using standard validated tools. Random-effects meta-analyses were conducted when !3 studies reported quantitative data for each outcome. Results: 32 RCT and 7 observational study publications were included. Meta-analysis of cognition-related outcomes could not be conducted due to heterogeneity of tests. None of the 5 cognition RCTs found significant effects of walnuts on overall cognition, although 3 studies found improvements on subdomains and/or subgroups. All 7 observational studies found significant associations and a dose-response relationship between walnut intake and cognition-related outcomes. Meta-analyses of 27 RCTs reporting glucose homeostasis and inflammation outcomes, selected risk factors for cognitive decline, did not show significant effects of walnut intake. Conclusions: Due to the non-uniformity of tests for cognition-related outcomes, definitive conclusions regarding the effect of walnut consumption on cognition could not be reached. Additionally, evidence does not show associations between walnut intake and glucose homeostasis or inflammation, cognitive decline risk-factors. High-quality studies with standardized measures are needed to clarify the role of walnuts in cognitive health. KEY MESSAGESThis is a systematic review and meta-analysis of 5 randomized clinical trials and 7 observational study articles of the impact of walnut intake on cognition decline and 27 randomized clinical trials of the effect of walnut intake on risk factors for cognitive decline including glucose homeostasis and inflammation. The non-uniformity of tests performed to measure cognitive function in the various studies did not allow for a meta-analysis of these studies. A definitive conclusion could therefore not be reached regarding the effect of walnut intake on cognitive decline. The evidence available does not show an association between walnut intake and glucose homeostasis or inflammation.

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Section: Discussionsupporting

confidence: 92%

Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis

et al. 2021

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“…Current evidence supports the recommendation of tree nut (i.e., almond, pistachio, walnut) and peanut intake for the prevention and nonpharmacological therapy of chronic conditions such as, dyslipidemia, type II diabetes mellitus, hypertension and cardiovascular mortality [ 1 , 2 , 3 ]. As nuts provide a substantial amount of energy (calories/g) [ 4 ] and have a high nutritional density [ 5 ], whether nutrient consumption leads to weight gain and increased body fat is a common concern [ 6 , 7 ].…”

Section: Introductionmentioning

confidence: 87%

The Role of Physical Fitness in the Relationship between Nut Consumption and Body Composition in Young Adults

et al. 2021

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The main objective of this study was to estimate the association between nut consumption and body composition-related measures and to examine whether this relationship is mediated by cardiorespiratory fitness (CRF) and the muscle strength index (MSI) in young adults. A cross-sectional study involving college students (n = 354) aged 18–30 years from a Spanish public university was conducted. Body composition and fitness components were assessed using standard methods. Nut consumption was evaluated using a Food-Frequency Questionnaire. ANCOVA models were used to assess the mean differences in physical fitness and body composition by nut consumption categories. Hayes’s PROCESS macro was applied for mediation and interaction analyses adjusted for the main confounders. Young adults with high nut consumption (≥5 portions of 30 g/week) showed significantly higher values of physical fitness components and fat-free mass and lower values of adiposity-related measures than their peers in the lowest categories of nut consumption (˂1 portion/week) (p < 0.05). No significant interaction between CRF and nut consumption on body composition was found. In the mediation analysis, CRF and MSI acted as full mediators of the relationship of nut consumption with fat-free mass and waist circumference/height index. Otherwise, CRF and MSI partially mediated the relationship between nut consumption and body mass index and percent of fat mass. Finally, nut consumption, per se, does not appear to have a significant impact on body composition indicators because these associations have been shown to be partially (for BMI and %BF) or entirely (for ratio WC/height and fat-free mass) explained by CRF and MSI.

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“…Pecans are particularly high in proanthocyanidins and ellagitannins, pistachios and almonds are high in proanthocyanidins, and walnuts are high in ellagitannins [ 101 ]. Consumption of pistachio nuts, according to 6 intervention studies, improved HOMA-IR through changes in fasting glucose [ 102 ], but a systematic review on walnuts concluded that there was no effect on fasting blood glucose or other measures of IR [ 103 ]. Although there are fewer reported studies on humans, pecan and almond consumption seem to improve HOMA-IR [ 104 , 105 ] and almonds are also effective at reducing IR in t2D patients [ 106 ].…”

Section: Dietary (Poly)phenolsmentioning

confidence: 99%

Effects of Polyphenols on Insulin Resistance

Williamson¹,

Sheedy²

2020

Nutrients

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Insulin resistance (IR) is apparent when tissues responsible for clearing glucose from the blood, such as adipose and muscle, do not respond properly to appropriate signals. IR is estimated based on fasting blood glucose and insulin, but some measures also incorporate an oral glucose challenge. Certain (poly)phenols, as supplements or in foods, can improve insulin resistance by several mechanisms including lowering postprandial glucose, modulating glucose transport, affecting insulin signalling pathways, and by protecting against damage to insulin-secreting pancreatic β-cells. As shown by intervention studies on volunteers, the most promising candidates for improving insulin resistance are (−)-epicatechin, (−)-epicatechin-containing foods and anthocyanins. It is possible that quercetin and phenolic acids may also be active, but data from intervention studies are mixed. Longer term and especially dose-response studies on mildly insulin resistant participants are required to establish the extent to which (poly)phenols and (poly)phenol-rich foods may improve insulin resistance in compromised groups.

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Effect of walnut consumption on markers of blood glucose control: a systematic review and meta-analysis

Cited by 29 publications

References 68 publications

Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis

Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis

The Role of Physical Fitness in the Relationship between Nut Consumption and Body Composition in Young Adults

Effects of Polyphenols on Insulin Resistance

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