Friday, October 17, 2008

Resveratrol in the News


Two new studies on resveratrol highlight possible benefits and a new food source.

From Science Daily:
Resveratrol Prevents Fat Accumulation In Livers Of 'Alcoholic' Mice

The accumulation of fat in the liver as a result of chronic alcohol consumption could be prevented by consuming resveratrol, according to a new study with mice. The research found that resveratrol reduced the amount of fat produced in the liver of mice fed alcohol and, at the same time, increased the rate at which fat within the liver is broken down.

Chronic alcohol consumption causes fat to accumulate and can lead to liver diseases, including cirrhosis and fibrosis of the liver. It can also result in liver failure. The study points to resveratrol as a possible treatment for alcoholic fatty liver disease, and as a way to prevent the disease in those who are at risk, but have not developed it.

Resveratrol is present in grapes, peanuts, berries and in red wine. Other research with mice has suggested resveratrol may have anti-cancer and anti-inflammatory properties. There is also evidence that it has cardiovascular benefits. However, these findings have not been extended to humans.

The study was carried out by Joanne M. Ajmo, Xiaomei Liang, Christopher Q. Rogers, Brandi Pennock and Min You, all of the University of South Florida Health Sciences Center, Tampa.

Activates cell signalers

The study builds on previous research, which suggests that alcohol inhibits two molecules that play a role in cell signaling and the breakdown of fats in the liver: AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1). When alcohol inactivates AMPK and SIRT1, it allows fat to accumulate. Resveratrol does the opposite -- activating AMPK and SIRT1, and helping to clear out fat.

In this study, the authors wanted to find out more about how this happens, at the molecular level. They divided mice into groups and fed all of them a low-fat diet. Some mice had resveratrol in their diet, some had resveratrol plus ethanol (alcohol), some had ethanol alone and some had neither ethanol nor resveratrol. The researchers used two different dose levels of resveratrol. At the end of the experiment, they examined the livers of the mice.

The researchers found, as they had expected, that resveratrol treatment increased the expression of SIRT1 and stimulated the activity of AMPK in the livers of mice fed alcohol. They further found that the increased expression of SIRT1 and AMPK led to:

  • Reduction of sterol regulatory element binding protein (SREBP-1)
  • Activation of peroxisome proliferator-activated receptor gamma co-activator alpha (PGC-1α)
  • Elevation of circulating adiponectin, a hormone produced by fat cells, which helps control obesity
  • Enhanced expression of adiponectin receptors in the liver, which increases the effectiveness of the circulating adiponectin.

The findings suggest that resveratrol prevents alcoholic fatty liver by coordinating molecules that control fat metabolism. This prevents accumulation of fat in the mouse liver by both reducing the production of fat and burning off the fat that is there. Interestingly, the combination of alcohol with resveratrol appears to enhance the positive effects of resveratrol, said Dr. You, the study's senior author.

"Our study suggests that resveratrol may serve as a promising agent for preventing or treating human alcoholic fatty liver disease," the authors concluded.


Journal reference:

  1. Ajmo et al. Resveratrol alleviates alcoholic fatty liver in mice. AJP Gastrointestinal and Liver Physiology, 2008; 295 (4): G833 DOI: 10.1152/ajpgi.90358.2008
Adapted from materials provided by American Physiological Society.

The second article appeared on Eureka Alert, a clearing house for scientific press releases -- note the possibility of bias in that the research was done by the Hershey Company, makers of dark chocolate and cocoa products.
Resveratrol, red wine compound linked to health, also found in dark chocolate and cocoa

Hershey's Center for Health and Nutrition announced the publication of a study that shows resveratrol, the compound often associated with the health benefits of red wine, is also found in cocoa and dark chocolate products. In the September 24 edition of the Journal of Agricultural and Food Chemistry, scientists report that cocoa powder, baking chocolate and dark chocolate all have significant levels of resveratrol, a naturally occurring antioxidant.

"This study shows that the levels of resveratrol found in cocoa and chocolate products is second to red wine among known sources of resveratrol and forms yet another important link between the antioxidants found in cocoa and dark chocolate to other foods," says David Stuart, PhD, Director of Natural Product Science at The Hershey Company who partnered with Planta Analytica to conduct this study.

In the study, top selling retail products from six categories were tested for the level of resveratrol and its sister compound, piceid. The six product categories included cocoa powder, baking chocolate, dark chocolate, semi-sweet baking chips, milk chocolate and chocolate syrup. Gram for gram, cocoa powder had the highest average amount of resveratrol and piceid, followed by baking chocolates, dark chocolates, semi-sweet chips, milk chocolate and then chocolate syrup. In the products studied, the level of piceid was 3 to 6 times the level of resveratrol.

When the cocoa and chocolate levels were compared to published values for a serving of red wine, roasted peanuts and peanut butter, resveratrol levels of cocoa powders, baking chocolates and dark chocolate all exceeded the levels for roasted peanuts and peanut butter per serving, but were less than California red wine.

"Resveratrol gained widespread attention in the early 1990s when it was identified in relatively high amounts in red wine, which is associated with the French Paradox," says Debra Miller, PhD, Director of Nutrition for The Hershey Company. "Despite eating a diet equally high in saturated fat as the typical American diet, the French were shown to have about one-third the level of cardiovascular disease. Continued research indicates that moderate consumption of red wine, along with fruits, vegetables, nuts and lower amounts of red meat, may contribute to this lower risk of heart of disease."

According to a review article published this month in Nutrition Reviews, resveratrol, a naturally occurring antioxidant, was shown to improve insulin sensitivity, blood cholesterol levels and have neuroprotective actions in animal studies. Further, the article states, studies in mice indicate that diets high in resveratrol were associated with increased longevity..

"Cocoa is a highly complex natural food which contains in excess of seven hundred naturally occurring compounds, with many more yet to be discovered," explains Jeff Hurst, the lead chemist on the project. "For years, flavanols, a different class of compounds in chocolate, received most of the attention, but these are quite different than resveratrol. It is exciting to see additional antioxidants identified in cocoa and chocolate."

The results of the survey show that cocoa powder, baking chocolate and dark chocolate contain on average 14.1 to 18.5 micrograms of resveratrol per serving while the level found in the average California red wine is 832 micrograms per glass. Roasted peanuts have an average of 1.5 micrograms and peanut butter13.6 micrograms of resveratrol per serving, demonstrating that cocoa and dark chocolates are meaningful sources of resveratrol in the US diet.

I'm not ready to recommend that anyone get their resveratrol from chocolate, but dark chocolate, at a low dose, is healthy as a part of the diet, so have at it. The best source is still from supplements, where you get the benefits without the calories (or alcohol in the case of wine).


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