Heart-Smart Tart Cherries

ANN ARBOR, Mich.Tart cherries touch the hearts of many Americans by way of the classic cherry pie, but the All-American dessert ingredient appears to also improve markers of cardiovascular health, including cholesterol, blood sugar and oxidative stress. According to researchers from the University of Michigan (UM) Health System, animals given powdered tart cherries in their diet had lower total cholesterol, lower blood sugar, less fat storage in the liver, lower oxidative stress, and increased production of a molecule that helps the body handle fat and sugar, compared with rats that didnt receive cherries as part of an otherwise similar diet. The researchers presented their findings at Experimental Biology 2007 in Washington, April 27 to May 2.

All of the rats in the study had a predisposition toward high cholesterol and pre-diabetes, but not obesity. For 90 days beginning in their sixth week of life, the rats were fed either a carbohydrate-enriched diet or a diet that included either 1- or 10-percent cherries. The higher cherry dose was included to investigate toxic effects; none were seen.

By the end of the study, the rats that received the 1-percent cherry diet had significantly lower total cholesterol, triglyceride, glucose and insulin levels than those of the rats that did not receive cherries. The same was true for those on the 10-percent cherry diet, compared with rats that received a diet with an equivalently high level of carbohydrates not from cherries.

The researchers also measured plasma TEAC, a test of antioxidant capacity in the blood, in which a higher reading means better ability to neutralize damaging free radical molecules produced in the body during metabolism. The rats that received cherries had higher antioxidant capacity (indicating lower oxidative stress in their bodies) than those that did not. As storage of excess fat is common in metabolic syndrome, researchers also measured fat levels in the rats livers, as well as the genetic expression of PPAR (peroxisome proliferator-activating receptor) in the liver. Rats receiving cherries had both a lower level of fat in their livers and a higher expression of the PPAR gene; the correlation between the two was dose-dependent.

The researchers concluded the correlation between cherry intake and significant changes in metabolic measurements suggest a positive effect from the high concentrations of antioxidant anthocyanins found in tart cherries. They are not certain if cherry-rich diets might have a similar impact in humans, but a small clinical trial is planned. Lead author E. Mitchell Seymour, M.S., supervisor UMs cardioprotection Research Laboratory, and Steven Bolling, M.D., a UM cardiac surgeon, cautioned these results cannot be directly translated into humans, but reveled in the positive data from the trial.

Rats fed tart cherries as one-percent of their total diet had reduced markers of metabolic syndrome, Seymour said. Previous research by other groups studied pure anthocyanin compounds, rather than anthocyanin-containing whole foods, and they used concentrations of anthocyanins that would be very difficult, if not impossible, to obtain in the diet.

For more information, visit http://sitemaker.umich.edu/cardiac.phytomed.