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Mechanisms underlying the cardiometabolic protective effect of walnut consumption in obese people: A cross‐over, randomized, double‐blind, controlled inpatient physiology study
Author(s) -
Tuccinardi Dario,
Farr Olivia M.,
Upadhyay Jagriti,
Oussaada Sabrina M.,
Klapa Maria I.,
Candela Marco,
Rampelli Simone,
Lehoux Sylvain,
Lázaro Iolanda,
SalaVila Aleix,
Brigidi Patrizia,
Cummings Richard D.,
Mantzoros Christos S.
Publication year - 2019
Publication title -
diabetes, obesity and metabolism
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.445
H-Index - 128
eISSN - 1463-1326
pISSN - 1462-8902
DOI - 10.1111/dom.13773
Subject(s) - medicine , clinical nutrition , physiology , insulin resistance , area under the curve , postprandial , metabolomics , obesity , endocrinology , food science , insulin , bioinformatics , biology
Abstract Aims To assess the effects of walnuts on cardiometabolic outcomes in obese people and to explore the underlying mechanisms using novel methods including metabolomic, lipidomic, glycomic and microbiome analysis, integrated with lipid particle fractionation, appetite‐regulating hormones and haemodynamic measurements. Materials and Methods A total of 10 obese individuals were enrolled in this cross‐over, randomized, double‐blind, placebo‐controlled clinical trial. The participants had two 5‐day inpatient stays, during which they consumed a smoothie containing 48 g walnuts or a macronutrient‐matched placebo smoothie without nuts, with a 1‐month washout period between the two visits. Results Walnut consumption improved aspects of the lipid profile; it reduced fasting small and dense LDL particles ( P < 0.02) and increased postprandial large HDL particles ( P < 0.01). Lipoprotein insulin resistance score, glucose and the insulin area under the curve (AUC) decreased significantly after walnut consumption ( P < 0.01, P < 0.02 and P < 0.04, respectively). Consuming walnuts significantly increased 10 N‐glycans, with eight of them carrying a fucose core. Lipidomic analysis showed a robust reduction in harmful ceramides, hexosylceramides and sphingomyelins, which have been shown to mediate effects on cardiometabolic risk. The peptide YY AUC significantly increased after walnut consumption ( P < 0.03). No major significant changes in haemodynamic or metabolomic analysis or in microbiome host health‐promoting bacteria such as Faecalibacterium were found. Conclusions These data provide a more comprehensive mechanistic perspective of the effect of dietary walnut consumption on cardiometabolic variables. Lipidomic and lipid nuclear magnetic resonance spectroscopy analysis showed an early but significant reduction in ceramides and other atherogenic lipids with walnut consumption, which may explain the longer‐term benefits of walnuts or other nuts on insulin resistance, cardiovascular risk and mortality.