Cranberry juice: what’s the evidence?

In traditional use, cranberry juice can be used to ease the symptoms of urinary tract infections (UTIs) and has been linked with heart health benefits. But what does the current evidence tell us about cranberry juice and health?

Urinary tract infections

Despite lay claims, there are few published clinical studies which have assessed cranberry juice intake and effects on UTI symptoms and length of infection. A systematic review from 2020 found three randomised controlled trials (RCT) which examined the effects of cranberry juice on UTIs [1]. Two of these found no benefits of cranberry juice intake on symptoms either when taken singly or combined with antibiotic use. The final RCT found that cranberry extract capsules did provide improvements in symptoms and a reduction in bacterial load compared to baseline, which was not found in the untreated control group.

Cardiovascular health

A crossover RCT in 40 middle-aged adults with high blood pressure gave participants 500ml cranberry juice or matched placebo for 8 weeks [2]. The results suggest that cranberry juice intake resulted in modest effects on 24-hr ambulatory diastolic blood pressure and lipoprotein profile.

Another RCT, using daily intake for one month of cranberry powder (equivalent to 100g fresh cranberries), increased flow mediated dilation, which researchers suggest is related to the concurrent increase in plasma metabolites seen after consumption [3].

A recent systematic review of RCTs assessing the effects of different types of fruit juice on markers of cardiovascular health found that cranberry juice significantly lowered systolic blood pressure by -1.52mmHg and diastolic blood pressure by -1.78mmHg [4].

A further systematic review and meta-analysis of RCTs suggests that the benefits of consuming cranberry juice on blood pressure may be most pronounced in older adults aged >50 years [5].

To conclude, while there may be anecdotal evidence for the use of cranberry juice to ease UTI symptoms and duration, the scientific literature is not supportive at present.

In terms of cardiovascular health, although the current evidence is suggestive of benefits to vascular health, further clinical data are required to confirm these early findings.

References

1 Gbingie OA et al. (2020) https://pubmed.ncbi.nlm.nih.gov/33375566/

2 Richter CK et al. (2021) https://pubmed.ncbi.nlm.nih.gov/34444779/

3 Heiss C et al. (2022) https://pubmed.ncbi.nlm.nih.gov/35322843/

4 Wang Y et al. (2021) https://pubmed.ncbi.nlm.nih.gov/32535781/

5 Pourmasoumi M et al. (2020) https://pubmed.ncbi.nlm.nih.gov/31023488/