Elaine Hardman, Ph.D., associate professor of medicine at Marshall University School of Medicine, said that while her study was done with laboratory animals rather than humans, people should heed the recommendation to eat more walnuts.

"Walnuts are better than cookies, french fries or potato chips when you need a snack," said Hardman. "We know that a healthy diet overall prevents all manner of chronic diseases."

Hardman and colleagues studied mice that were fed a diet that they estimated was the human equivalent of two ounces of walnuts per day. A separate group of mice were fed a control diet.

Standard testing showed that walnut consumption significantly decreased breast tumor incidence, the number of glands with a tumor and tumor size.

"These laboratory mice typically have 100 percent tumor incidence at five months; walnut consumption delayed those tumors by at least three weeks," said Hardman.

Molecular analysis showed that increased consumption of omega-3 fatty acids contributed to the decline in tumor incidence, but other parts of the walnut contributed as well.

"With dietary interventions you see multiple mechanisms when working with the whole food," said Hardman. "It is clear that walnuts contribute to a healthy diet that can reduce breast cancer."

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Although the current study was supported in part by the California Table Grape Commission, which also supplied the grape powder, the authors note that the commission played no role in the study's design, conduct, analysis or the preparation of the journal article for publication. Seymour also receives funding from the National Heart, Lung and Blood Institute, part of the National Institutes of Health, through a National Research Service Award.

Bolling said the latest results take research on the health benefits of grapes "a step further" by examining the mechanisms impacted by antioxidant-rich grapes.

The rats in the study were from a strain called Dahl rats, which have been specially bred to all be susceptible to salt-induced hypertension. The animals are similar to

Americans who have elevated blood pressure related to diet, and who develop heart failure over time because of prolonged hypertension.

Each group of 12 rats was fed the same weight of food each day with powdered grapes making up 3 percent of the diet (by weight) for rats that received grapes as part of either a low-salt or high-salt diet. The rats that received hydrazine were fed it through their water supply in a dose that has been previously shown to be effective in reducing blood pressure.

Such naturally occurring chemicals have already been shown in other research, including previous U-M studies, to reduce other potentially harmful molecular and cellular activity in the body.

In all, the researchers say, the study further demonstrates that a grape-enriched diet can have broad effects on the development of hypertension and the risk factors that go with it. Whether the effect can be replicated in humans, they say, remains to be seen.

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