Cranberry juice may help protect against heart disease

Apr 3 2005

Protection against a wide variety of diseases is among the many benefits of a diet high in whole fruits and vegetables. Cranberries over the years have been identified with preventing or ameliorating urinary tract infections and playing a positive role gum disease, ulcers and even cancer.

Recent work shows that cranberries contain naturally derived compounds (antioxidants, flavonoids, and polyphenols) that may help protect against heart disease. Researchers at the University of Wisconsin-Madison School of Veterinary Medicine studied the effects of taking cranberry juice powder regularly over six months and found a pronounced improvement in the vascular function -- the ability of blood vessels to relax – in subjects with high blood cholesterol and atherosclerosis.

"Since the abnormal functioning of blood vessels is an important component of heart disease, finding ways to improve vascular function in patients with high cholesterol and atherosclerosis is critical to helping protect these patients from consequences such as heart attack or stroke," according to lead researcher Kris Kruse-Elliott.

"The value of fruits and vegetables in our diet has recently been an area of intense research and studies like this help us to understand the specific mechanisms by which the nutrients we consume can protect against heart disease," Kruse-Elliott said. She said that the next steps are "to determine what specific components of cranberries are most important to the improvements in vascular function that we observed, exactly how they modify blood vessel relaxation, and how they can be most easily consumed as part of the diet."

Kruse-Elliott's collaborator, Jess Reed has been working with other foods such as pomegranates and grape seed extract, as well as whole cranberries. According to Reed, "the equivalent consumption of dried cranberries would be 4-8 servings, or 10-20 servings of cranberry juice, in order to achieve the levels in the current study. However, the point to be emphasized is that total polyphenol intake is very low in western diets and a diet rich in polyphenols would in fact give a daily intake that is equivalent to the levels in our cranberry feeding experiments."

Kruse-Elliott added: "We're lucky to have a unique animal model for atherosclerosis – familial hypercholesterolemic (FH) swine, whose genetic defect causes them to spontaneously develop high blood cholesterol leading to atherosclerosis and vascular dysfunction by eight months of age, very similar to the way human beings do." She noted that the FH pigs' blood vessels don't function normally, such as not relaxing well, compared with normal pigs.

"However when the FH pigs were fed cranberry juice powder, made from whole cranberries, for six months their vessels acted more like normal pigs, Kruse-Elliott said. FH pigs who didn't get cranberry juice powder had "significantly less vascular relaxation" than either normal or cranberry-fed pigs. The pigs on the CJP diet received 150g/kg per day.

Next steps. A series of experiments are planned to dig deeper into the cranberry-vessel function link in several cases applying tests used on humans to the pigs. For instance people with atherosclerosis take flow-mediated vasodilation tests using ultrasound to measure the change in size of the blood vessels and in flow rate. "We also will be measure CRP (C-reactive protein), which some people think is a predictor of cardiovascular disease," Kruse-Elliott said. "Furthermore, we want to correlate all those findings with LDL (levels), which should yield important physiological results as well as further validating the FH model," she said.

And what will be the diet of choice in the next stage? It turns out pigs like whole cranberries. Tart and yummy.