In comprehensive studies recently published in the journal Foods, it was reported by a team led by Dr. John Pezzuto of Western New England University, that long-term addition of grapes to the diet of mice leads to unique gene expression patterns, reduces fatty liver and extends the lifespan of animals consuming a high-fat western style diet.
Pezzuto, who is an author of over 600 papers in the scientific literature, said he was especially amazed by these results. "We have all heard the saying 'you are what you eat' which is obviously true since we all start out as a fetus and end up being an adult by eating food. But these studies add an entirely new dimension to that old saying. Not only is food converted to our body parts, but as shown by our work with dietary grapes, it actually changes our genetic expression. That is truly remarkable."
What is the effect of this alteration of gene expression? As shown in this paper, fatty liver, which affects around 25% of the world's population and can eventually lead to untoward effects, including liver cancer, is prevented or delayed. The genes responsible for the development of fatty liver were altered in a beneficial way by feeding grapes. In ancillary work, recently published by a collaborative team led by Dr. Jeffrey Idle in the journal Food & Function, not only is the expression of genes altered, but metabolism is also changed by dietary grapes.
In addition to genes related to fatty liver, the work found increased levels of antioxidant genes with the grape-supplemented diets. According to Pezzuto, "Many people think about taking dietary supplements that boast high antioxidant activity. In actual fact, though, you cannot consume enough of an antioxidant to make a big difference. But if you change the level of antioxidant gene expression, as we observed with grapes added to the diet, the result is a catalytic response that can make a real difference."
Another remarkable effect illustrated in this work was the ability of grapes to extend the lifespan of mice given a high-fat western pattern diet. The high-fat western pattern diet is known to be associated with adverse conditions such as obesity, diabetes, cardiovascular diseases, cancer, autoimmune diseases, and Alzheimer's disease. Adding grapes to the diet, which did not affect the rate of consumption or body weight, delayed natural death. Although it is not an exact science to translate years of lifespan from a mouse to a human, Pezzuto notes that his best estimate is the change observed in the study would correspond to an additional 4-5 years in the life of a human.
Precisely how all of this relates to humans remains to be seen, but it is clear that the addition of grapes to the diet changes gene expression in more than the liver. In studies recently published in the journal Antioxidants by Pezzuto and his team, it was found that grape consumption alters gene expression in the brain. At the same time, grape consumption had positive effects on behavior and cognition that were impaired by a high-fat diet, suggesting the alteration of gene expression produced this beneficial response. More studies are required, but it is notable that a team led by Silverman at UCLA reported that the daily administration of grapes had a protective effect on brain metabolism. It now may be suggested this is due to alteration of gene expression.
The grapes used in these studies were provided by the California Table Grape Commission, who partially supported the work as well. Kathleen Nave, president of the commission, noted that the grape growers of California are proud to have supported grape research at over 70 institutions throughout the US and the world for over 20 years. She stated that "Grape growers in California have had the privilege of supporting scores of projects over the years. Some studies have shown positive effects on health, and others have not been as promising. The results reported by John Pezzuto and his team are exciting and rewarding on many levels. The potential for improvements in human health is significant as is the strength of the data which logically supports the need for follow-up work in human clinical trials. All of this is rewarding to the growers who have funded research year after year with the sole objective of following the science and learning what we could from high caliber peer-reviewed research. Studies like the ones reported here are not only rewarding to grape growers and of interest to the scientific community, but are of value to everyone who wants to optimize their health and understands that what we eat matters. We can't ask for more than that."
