Daily walnut intake improves metabolic syndrome status and increases circulating adiponectin levels: randomized controlled crossover trial

Abstract

BACKGROUND/OBJECTIVES Several previous studies have investigated whether regular walnut consumption positively changes heart-health-related parameters. The aim of this study was to investigate the effects of daily walnut intake on metabolic syndrome (MetS) status and other metabolic parameters among subjects with MetS. SUBJECTS/METHODS This study was a two-arm, randomized, controlled crossover study with 16 weeks of each intervention (45 g of walnuts or iso-caloric white bread) with a 6 week washout period between interventions. Korean adults with MetS (n = 119) were randomly assigned to one of two sequences; 84 subjects completed the trial. At each clinic visit (at 0, 16, 22, and 38 weeks), MetS components, metabolic parameters including lipid profile, hemoglobin A1c (HbA1c), adiponectin, leptin, and apolipoprotein B, as well as anthropometric and bioimpedance data were obtained. RESULTS Daily walnut consumption for 16 weeks improved MetS status, resulting in 28.6%-52.8% reversion rates for individual MetS components and 51.2% of participants with MetS at baseline reverted to a normal status after the walnut intervention. Significant improvements after walnut intake, compared to control intervention, in high-density lipoprotein cholesterol (HDL-C) ( P = 0.028), fasting glucose ( P = 0.013), HbA1c ( P = 0.021), and adiponectin ( P = 0.019) were observed after adjustment for gender, age, body mass index, and sequence using a linear mixed model. CONCLUSION A dietary supplement of 45 g of walnuts for 16 weeks favorably changed MetS status by increasing the concentration of HDL-C and decreasing fasting glucose level. Furthermore, consuming walnuts on a daily basis changed HbA1c and circulating adiponectin levels among the subjects with MetS. This trial is registered at ClinicalTrials.gov as NCT03267901 .

Effects of walnut intake on blood pressure: A systematic review and meta‐analysis of randomized controlled trials

“…In general, studies before 2004 did not provide adequate data for our analyses. Studies were conducted in the United States (Al Abdrabalnabi et al, 2020; Katz et al, 2012; Ma et al, 2010; Njike, Ayettey, Petraro, Treu, & Katz, 2015; Rock, Flatt, Barkai, Pakiz, & Heath, 2017; Spaccarotella et al, 2008; Tindall et al, 2019), Republic of Korea (Hwang et al, 2019), Australia (Ndanuko, Tapsell, Charlton, Neale, & Batterham, 2018), Iran (Fatahi, Haghighatdoost, Larijani, & Azadbakht, 2019; Nezhad, Aghasadeghi, Hakimi, Yarmohammadi, & Nikaein, 2016), United Kingdom (Din et al, 2011), Spain (Olmedilla‐Alonso et al, 2008; Ros et al, 2004; Sanchis et al, 2019), Chine (Wu et al, 2010), and New Zealand (Mukuddem‐Petersen, Stonehouse Oosthuizen, Jerling, Hanekom, & White, 2007). The follow‐up period ranged from 4 weeks to 2 years.…”

Menopause-Associated Lipid Metabolic Disorders and Foods Beneficial for Postmenopausal Women

“…These nutrients are commonly found in fruits, vegetables, soybean, cocoa, and tea leaf extracts. The highest antioxidant content is found in almonds [152], artichokes, blackberries, blueberries, cherries (sour), chokeberry [153], chocolate (dark, unsweetened), cloves, ground cranberry juice, coffee, cranberries, grape juice, cranberry juice, pomegranate juice, pecans, raspberries, spinach, strawberries, walnuts [154], and red wine [134]. Recently, the administration of olive leaf extract [155] and Hawthorn fruit extract [156] was reported to improve serum lipid profiles in OVX mice via elevating mRNA expression of adiponectin and PPAR-α.…”

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

“…Ten randomized (5 crossover [40][41][42][43][44] and 5 parallel [45][46][47][48][49]) trials reporting HbA1c were included. Of these, one study was conducted in overweight or obese subjects [47], five were in subjects at risk for [43] or with T2D [42,45,46,49], two were in subjects with metabolic syndrome (MetS) [41,48], and two were in generally healthy individuals [40,44]. Walnut intervention doses ranged from 15 to 56 g/day of walnuts and/or walnut oil and intervention durations ranged from 8 weeks to 14 months (Table 5).…”

“…Findings were relatively consistent; seven of the ten studies did not find a significant difference in HbA1c between control and walnut interventions. Two studies found that walnut significantly decreased HbA1c [41,49], and one study found that walnut significantly increased HbA1c [40]. However, random-effects metaanalysis of these ten trials did not find significant overall effects of walnut on HbA1c (pooled net change ¼ 0.02%; 95% CI À0.03%, 0.08%) with high statistical heterogeneity (I 2 ¼ 96.8%; p < .0001) (Figure 4).…”