Daily servings of cranberry juice increase HDL and plasma antioxidant levels in human subjects

March 26, 2003

Wed, 26 Mar 2003 14:30:00

New Orleans, LA - Although researchers have long suspected antioxidant-rich cranberry juice may help lower the risk factors for heart disease, authors of a recent long-term study have shown three servings of cranberry juice in hypercholesterolemic subjects increased plasma antioxidant capacity by as much as 121% and decreased lipid peroxidation products up to 36%. Long-term consumption of three servings of cranberry juice daily also resulted in a 10% increase in HDL, say investigators.

The study, led by Dr Joe Vinson (University of Scranton, PA), was presented at the 225th National Meeting of the American Chemical Society. It is the first long-term study of the effect of cranberry juice on cholesterol levels.

In the dose-response supplementation study, investigators measured cholesterol levels in 20 hypercholesterolemic subjects not currently taking medication. Plasma antioxidant capacity was measured by the ferric reducing ability of plasma (FRAP) assay. Plasma lipid peroxides were measured by xylenol orange/ferrous ion colorimetry using hydrogen peroxide as the standard.

Twelve subjects consumed cranberry juice without high-fructose corn syrup, substituting an artificial sweetener, while the remaining subjects consumed cranberry juice with sugar. Standard serving size was 240 mL. For the first month, subjects in both groups consumed one serving of cranberry juice. The next month the subjects consumed two daily servings of cranberry juice and finally three daily servings of cranberry juice in the third month. Total cholesterol, HDL, LDL, plasma antioxidant capacity, and lipid peroxidation products were measured after each month. A washout period of three months occurred after which the subjects were again sampled. Subjects were not monitored with respect to exercise, diet, or alcohol consumption.

Baseline measurements and blood samples were taken after fasting and taken again in three one-month intervals. Vinson et al found the cranberry juice had no effect on total cholesterol and LDL but did significantly increase HDL by 10% at the highest dose. HDL increased from 48 mg/dL at baseline to 53 mg/dL in subjects consuming three servings of cranberry juice per day. Based on analyses from the Framingham Heart Study, a 10% increase in HDL translates into a 40% reduction in heart disease risk, write investigators.

Plasma antioxidant capacity increased from 107 mol at baseline to 226 mol in subjects consuming two servings of cranberry juice daily and 236 mol in subjects consuming three servings of cranberry juice daily. Lipid peroxidation products decreased from 210 mol at baseline to 180 mol after one month, 160 mol after two months, and 135 mol after three months.

"Our research in the past has shown that cranberries have more phenol antioxidants than any of the most commonly consumed fruits," said Vinson in an interview with heartwire . "Aside from grape juice, cranberry juice has been shown to have more antioxidants than a lot of the common breakfast juices currently on the market."

The cranberry juice tested in the study contained approximately 27% pure cranberry juice by volume, similar to the supermarket variety. Vinson noted, however, the quality of phenol antioxidants in cranberry juice is not compromised by processing, as measured by an in vitro test that simulated the oxidation of LDL. Just one serving of 240 mL of cranberry juice provides 137 mg of polyphenols, said Vinson.

Despite long-term consumption of up to three glasses of cranberry juice a day, cranberry juice did not result in weight gain, said Vinson. "In fact, what we witnessed was a small weight loss in the subjects of about two pounds."

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