Cranberries Care for Cardiovascular Health

Dr Rob Hicks

March 23, 2022

Blood vessel function improved in men following daily consumption of cranberries for a month. Researchers suggest the amount of cranberry needed to achieve these benefits was realistically achievable.

In the new study, published in the journal Food & Function, researchers from King's College London and the University of Surrey set out to investigate the impact of consumption of freeze dried whole cranberries in healthy men.

The authors said that previous studies had indicated cardiovascular health benefits from cranberry juice consumption, but whether daily consumption of whole cranberries had sustained vascular benefits was unknown.

For their research they performed a double-blind, parallel-group, randomised controlled trial that included 45 healthy men aged 18-45 years old and without cardiovascular disease - including coronary artery disease, cerebrovascular disease and peripheral artery disease - diabetes mellitus, acute inflammation, terminal renal failure, malignancies, and heart rhythm other than sinus.

23 men consumed whole cranberry powder (9g powder) equivalent to 100g of fresh cranberries per day, and 22 men consumed a placebo, for one month. This main study followed on from a successful pilot study involving 5 healthy men to confirm the biological activity of the whole cranberry freeze-dried powder.

The primary endpoint of the study was flow-mediated dilation (FMD) – which measures how blood vessels widen when blood flow increases, and is considered a sensitive biomarker of cardiovascular disease risk – through measurement of the diameter and flow velocity of the brachial artery.

Secondary endpoints were pulse wave velocity (PWV), aortic augmentation index (AIx), blood pressure, heart rate, blood lipids, and blood glucose.

Assessment was made at baseline, at 2 hours on day 1, and after one month. Plasma and 24-hour urine were also analysed before and after treatment.

Improvement of Heart and Blood Vessel Function

The researchers found those consuming cranberry had a significant improvement compared with controls of 1.1% (95% CI: 1.1%, 1.8%) in FMD, which they said, "signals improvement of heart and blood vessel function", adding that these improvements in FMD showed both "immediate and longer-term benefit". In addition, metabolites were also identified and predicted the positive effects seen in FMD.

Dr Ana, Senior Lecturer in Nutrition at King's College London and senior author of the study, said, "The increases in polyphenols and metabolites in the bloodstream and the related improvements in flow-mediated dilation after cranberry consumption emphasise the important role cranberries may play in cardiovascular disease prevention."

The secondary outcomes, however, did not show any significant differences between responses to cranberry and control interventions, the authors said.

Achievable Cranberry Consumption

Dr Christian Heiss, Professor of Cardiovascular Medicine at the University of Surrey, and co-author of the study said, "Our findings provide solid evidence that cranberries can significantly affect vascular health even in people with low cardiovascular risk. This study further indicates that specific metabolites present in blood after cranberry consumption are related to the beneficial effects."    

The authors pointed out some limitations of their research, including how their study was conducted in a healthy cohort of young male volunteers and is, therefore, limited in its generalisability towards the general population and people at increased risk.

Also, they said the short 1-month study duration limits conclusions with regards to potential clinically relevant health benefits that would require that the short-term vascular protective effects are maintained over long periods of time. "Along these lines, some potential health benefits that may take longer to manifest may be not detected", they said.

The authors explained how low consumption of fruits and vegetables is one of the top modifiable risk factors associated with a higher incidence of cardiovascular disease worldwide. "These results demonstrate that consumption of cranberries as part of a healthy diet can play an important role in supporting cardiovascular health and good blood vessel function", they said.

Dr Rodriguez-Mateos emphasised, "The fact that these improvements in cardiovascular health were seen with any amount of cranberries that can be reasonably consumed daily makes cranberry an important fruit in the prevention of cardiovascular disease for the general public."

The study was supported by The Cranberry Institute who provided the whole cranberry and placebo powders.

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