Impact of California table grapes on systemic inflammation, insulin resistance, and hepatic steatosis in mice fed an American-type diet

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Jessie Baldwin (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Michael McIntosh

Abstract: The incidence of obesity is increasing worldwide, currently affecting over 400 million people. With obesity, expansion of white adipose tissue (WAT) contributes to a chronic, low-grade inflammatory response that is associated with the formation of complications such as type 2 diabetes, cardiovascular disease, and hypertension. One potential method of reducing chronic inflammation associated with obesity is through consumption of table grapes, which contain fiber and are rich in phytochemicals with potential health promoting properties. Several clinical trials and animal studies have demonstrated that consumption of grape products (i.e. grape seed extract, grape juice, or California powdered table grapes) can reduce oxidative stress, insulin resistance, and inflammation, as well as improve heart health. However, there is still much to be elucidated concerning the mechanisms by which grapes or grape products exert beneficial effects and which compounds within grapes are active in the mediation of these effects. Additionally, the influence of grape polyphenols and fiber on gut microbiota and the link of this with improvements in adiposity, systemic inflammation and insulin resistance are unclear. Therefore, the specific aims of this research were to (i) determine the extent to which California table grapes attenuate body fat accumulation, systemic inflammation, and insulin resistance, and impact gut microbiota in mice fed and American type diet rich in butter (Aim 1), and (ii) identify the key bioactive fraction(s) responsible for reducing adiposity, inflammation, and insulin resistance, and modulating gut microbiota in mice fed an American-type diet rich in four types of saturated fat (Aim 2). In Aim 1, grape consumption at one or both levels (i.e. 3% or 5% w/w) attenuated accumulation of body and liver fat, but these lipid lowering effects were not associated in improvements in glucose tolerance or markers of inflammation in WAT. Alterations in microbial species (i.e. reductions in deleterious sulfidogenic bacteria and increases in beneficial bacteria) were observed in grape-fed mice. Taken together these data demonstrate that consuming grapes results in attenuations in adiposity and hepatic steatosis, and also alterations gut microbial populations in mice fed a butter-rich diet. In Aim 2, consumption of the extractable polyphenol fraction (EP) alone or with the non-extractable polyphenol fraction (EP+NEP), but not powdered grapes (GP), reduced adiposity, liver and plasma triglycerides, markers of inflammation within WAT, and improved insulin sensitivity in mice fed a diet rich in saturated fat from four sources. Taken together, these data demonstrate that (i) consumption of polyphenols extracted from powdered grapes is effective at preventing the complications of diet-induced obesity, and that (ii) the effects of powdered grapes differ based on the amount and source of dietary fat. Overall, the findings from Aim 1 and Aim 2 are anticipated to contribute to the development of novel dietary strategies using grapes or grape products to manage or treat diet-induced obesity and associated conditions. Further research studies, including clinical trials, are still warranted to determine the applicability of these findings to the human population.

Additional Information

Language: English
Date: 2015
Grape, Gut microbiota, Hepatic steatosis, High fat, Inflammation, Obesity
Table grapes $x Therapeutic use
Fatty liver $x Nutritional aspects
Obesity $x Treatment

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