Research
Tart cherries may reduce risk of heart disease, diabetes

Tart cherries — frequently sold dried, frozen or in juice — may have more than just good taste and bright red color going for them, according to new animal research from the Cardiovascular Center.

Rats that received whole tart cherry powder mixed into a high-fat diet didn't gain as much weight or build up as much body fat as rats that didn't receive cherries. And their blood showed much lower levels of molecules that indicate the kind of inflammation that has been linked to heart disease and diabetes. In addition, they had significantly lower blood levels of cholesterol and triglycerides than the other rats.

The results, which were seen in both lean and obese rats that were bred to have a predisposition to obesity and insulin resistance, were presented last week at the Experimental Biology 2008 meeting in San Diego.

In addition, the obese rats that received cherry powder were less likely to build up fat in their bellies — another factor linked to cardiovascular disease. All the measures on which the two groups of animals differed are linked to cardiovascular disease and Type 2 diabetes.

The new findings build on results that were reported last year at the same meeting by the U-M team. Those data came from experiments involving lean rats that were prone to high blood pressure, high cholesterol and impaired glucose tolerance, but that received a low-fat diet with or without cherries. In that case, cherry-fed rats had lower total cholesterol, lower blood sugar, less fat storage in the liver and lower oxidative stress. However, it was unknown if these benefits would be observed in obesity-prone animals, or in animals fed a higher fat, western-style diet containing elevated saturated fat and cholesterol.

While it's still far too early to know whether tart cherries will have the same effect in humans, U-M researchers are preparing to launch a pilot-phase clinical trial later this spring. They note that if a human wanted to eat as many tart cherries as the rats in the new study did, they would have to consume 1.5 cups every day.

"These new findings are very encouraging, especially in light of what is becoming known about the interplay between inflammation, blood lipids, obesity and body composition in cardiovascular disease and diabetes," says Dr. Steven Bolling, a cardiac surgeon and the laboratory's director. "The fact that these factors decreased despite the rats' predisposition to obesity, and despite their high-fat 'American-style' diet, is especially interesting."

"It was recently shown in humans that regular intake of darkly pigmented fruits like cherries is associated with reduced mortality from cardiovascular disease and coronary heart disease," says research associate and senior scientist E. Mitchell Seymour. The correlation between cherry intake and significant changes in cardiovascular risk factors suggests — but does not directly demonstrate — a positive effect from the high concentrations of antioxidant compounds called anthocyanins that are found in tart cherries. The anthocyanins are responsible for the color of these and of other darkly pigmented fruits.

The cherries were Montmorency tart cherries grown in Michigan, which is the nation's largest producer of tart cherries. They are different from the sweet Bing cherries that are often eaten fresh. Tart cherries have higher concentrations of antioxidant anthocyanins than sweet cherries.

The research team also includes Daniel Urcuyo-Llanes, Ara Kirakosyan, Peter Kaufman and Sarah Lewis of U-M.