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Cranberry juice modestly lowers blood pressure in healthy adults when consumed daily, a carefully controlled trial showed.
Systolic and diastolic blood pressure both fell by an average 3 mm Hg with two 8-oz. glasses a day for 8 weeks, Janet Novotny, MD, of the U.S. Department of Agriculture in Beltsville, Md., and colleagues found.
The effect was significant compared with placebo for diastolic pressure, with a trend for systolic reduction as well, the group reported at the American Heart Association's High Blood Pressure Research meeting in Washington.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Note that this double-blind, randomized, placebo-controlled trial suggests that a low-calorie cranberry juice beverage appears to result in improvements in blood pressure in healthy adults.
Cranberry juice contains a "broad and interesting array" of the kind of plant flavonoids shown to reduce cardiovascular disease risk in epidemiologic studies, Novotny explained in an interview.
"If [patients] are trying to reduce blood pressure through diet, low-calorie cranberry juice would be something that would be good and healthful to include in that diet" as a replacement for less healthy drinks, she told MedPage Today.
The antihypertensive effect may be another reason to recommend cranberry juice in addition to its urinary tract benefits, commented Rachel Johnson, PhD, RD, chair of the American Heart Association's nutrition committee.
The use of a low-calorie cranberry juice may have been an important factor, she explained in an interview with MedPage Today.
"Cranberries on their own can be quite sour and they need to be sweetened in order to be palatable to people," said Johnson, a professor of nutrition and medicine at the University of Vermont in Burlington.
"Regular calorie cranberry juice can be quite high in added sugar and high in calories, so I do recommend that people look for the lower-calorie option in cranberry juice."
The study included 56 healthy adults without hypertension (mean age 51, body mass index 28.4 kg/m2) randomized double-blind to drink 8 oz. of a low-calorie cranberry juice drink or a color, flavor, and calorie-matched placebo at breakfast and dinner daily for 8 weeks.
The rest of their diet was controlled to keep body weight stable during the trial, with all meals provided by the research center to minimize variation.
At the end of the treatment period, the average diastolic blood pressure was lower in the cranberry juice group at 69 mm Hg versus 72 mm Hg with placebo (P=0.029).
The cranberry juice group also saw blood pressure lowering compared with baseline:
- Diastolic blood pressure fell from 74 to 71 mm Hg (P=0.049)
- Systolic blood pressure declined from 122 to 119 mm Hg (P=0.12)
The placebo group saw no change from baseline in either blood pressure measurement (P=0.89 and P=0.37, respectively).
Most food intervention studies show a systolic effect without a diastolic impact when lowering blood pressure, Novotny noted.
The trend didn't meet traditional criteria for statistical significance, but the 89% odds of a systolic blood pressure reduction with the cranberry juice was still pretty good, she suggested.
Johnson noted that the study may need to be replicated because of the fairly small sample size.
From the American Heart Association:
Disclosures
The study was funded by Ocean Spray Cranberries, which provided the study drink. Novotny reported research support from the company.
One of the co-authors was an employee of Ocean Spray Cranberries.
Johnson reported having received research funds from the Dairy Research Institute.
Primary Source
High Blood Pressure Research meeting
Source Reference: Novotny JA, et al "Low calorie cranberry juice lowers blood pressure in healthy adults" HBPR 2012; Abstract 299.