The Ingestion of Whole Fruit Compared to Fruit Juice Differentially Modulates Glucose, Insulin and Inflammatory Pathways

• Published in: Current developments in nutrition Vol. 4; no. Supplement_2; p. nzaa058_009
• Main Authors: Chodur, Gwen, Randolph, Jody, Bardagjy, Allison, Steinberg, Francene
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Inc 01.06.2020; Oxford University Press
• Subjects: Carbohydrates; Gastroenterology and Hepatology; Gene expression; Glucose; Insulin; MicroRNAs; Nutrient-Gene Interactions; Protein expression; Proteins
• ISSN: 2475-2991; 2475-2991
• DOI: 10.1093/cdn/nzaa058_009

To determine if equivalent amounts of carbohydrate ingested in the form of whole grapes or grape juice have differential effects on glucose, insulin, gene expression, protein content, and microRNA profiles following ingestion. Following an overnight fast, subjects consumed equivalent amounts of carbohydrate from whole grapes, grape juice, or glucose standard in randomized order. Blood was collected at fasted baseline and at 15, 30, 45, 60, 90, 120, and 180 minutes following ingestion of the test food. Glucose was quantified enzymatically and insulin was measured through radioimmunoassay and AUC was calculated. Peripheral blood mononuclear cells were isolated at baseline, 60, 120, and 180 minute time points and stored at –80°C for later analysis of gene expression, protein content, and microRNA profiles. Gene expression and mircoRNA will be measured using qtPCT. Protein expression will be determined using Western blots. Folin-Ciocalteu was used to determine total polyphenol counts of grapes and grape juice. Glucose and insulin responses between three treatments was analyzed using repeated measures ANOVA with Tukey’s posthoc. Fourteen subjects (64.3% female) participated in the study; 12 had complete data. Glucose and insulin dropped below baseline in some subjects, so the absolute value of AUC was calculated for each treatment. The absolute value of glucose was significantly different when comparing whole grapes to grape juice (1189.03 vs. 2787.38, p > 0.001) and significant differences were also seen in the absolute value of insulin (1399.93 vs 2732.34, P = 0.002). As a secondary analysis, we will investigate whether these differences manifest in upregulation of pathways related to inflammation. Gene expression, protein expression, and microRNA analyses are ongoing. Healthy adults have intra-individual variation in glycemic response to equivalent amounts of carbohydrate, depending on the matrix in which the carbohydrate is delivered. This response may result in differences in inflammatory processes, which should be considered in dietary recommendations. This research was supported through internal funds at the University of California, Davis, as well as Jastro-Shields and Kirvin Knox Fellowships.