Grape polyphenols help counter negative effects of high fat diet

Wednesday, May 18, 2016 by: David Gutierrez, staff writer
Tags: grapes, polyphenols, heart disease prevention

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(NaturalNews) Grape polyphenols may help protect the body from the effects of a diet high in fat, according to two studies conducted by researchers from the University of North Carolina Greensboro, and published in the Journal of Nutritional Biochemistry.

"These two studies suggest that grapes and grape polyphenols may help offset a number of the adverse effects of consuming a high fat diet and trigger improvements in intestinal or systemic health," lead researcher Michael McIntosh said. "This is an exciting area of health that merits further study."

Many of the famous health benefits of red wine, such as reduced cardiovascular disease risk, are thought to stem from plant compounds known as polyphenols. Grape skins are particularly high in these compounds. In addition to having high antioxidant activity, polyphenols may also help block the production of a protein that plays a role in cardiovascular disease.

Striking changes to microbiome

In the first study, researchers fed rats a diet high in butterfat, providing 33 percent of daily calories from fat, with grapes comprising 3 percent of their diet. After 11 weeks, rats eating the grape-spiked high-fat diet had significantly less subcutaneous fat and overall body fat, improved gut barrier function, increases in gut microbial diversity, and increases in beneficial gut bacteria, combined with decreases in more harmful bacteria.

The second study was conducted on rats getting 44 percent of their calories from fat, including highly saturated fat sources such as butter, shortening, beef tallow and lard. The researchers identified this diet as similar to many Western diets. Some of the rats had 5 percent of their diet come from grapes, while others were supplemented with either the polyphenol or non-polyphenol portions of grapes. All the diets contained the same amounts and types of sugar.

After 16 weeks, rats whose diets were supplemented with whole grapes showed improvements to microbial balance similar to those in the first study. The rats given polyphenols, however, showed decreased subcutaneous and visceral fat deposits and overall body fat percentage, lowered inflammation in the liver and fatty deposits, improved gut barrier function and improved glucose tolerance. These changes all suggest a decreased risk of metabolic syndrome – the cluster of symptoms linked to the development of cardiovascular disease and diabetes.

Gut microbes are now thought to play an important role in regulating metabolism, and imbalances in those microbes may contribute to metabolic syndrome.

Polyphenols also prevent organ damage

The study is only the latest in a long line of research exploring the metabolic benefits of grape polyphenols. A study conducted by researchers from the University of Michigan, and presented at the Experimental Biology conference in 2013, found that grape consumption might help prevent the organ damage associated with metabolic syndrome.

In that study, researchers took obesity-prone rats and fed them a high-fat, U.S.-style diet either with or without added grapes. The researchers found that rats on the grape-supplemented diet showed lower levels of inflammatory markers than the control rats, particularly in the liver and abdominal fat. They also showed higher antioxidant activity, especially in the liver and kidneys. The grape-eating rats also had less fat in the abdomen, liver and kidneys.

"Our study suggests that a grape-enriched diet may play a critical role in protecting against metabolic syndrome and the toll it takes on the body and its organs," lead researcher E. Mitchell Seymour said. "Both inflammation and oxidative stress play a role in cardiovascular disease progression and organ dysfunction in Type 2 diabetes. Grape intake impacted both of these components in several tissues which is a very promising finding."

In prior research, Seymour found that obesity-prone rats fed grape-enriched diets showed decreases in risk factors for diabetes and heart disease.

Sources for this article include:

EurekAlert.org

ScienceDaily.com

NaturalNews.com

Science.NaturalNews.com