Cranberry: Good for more than just UTIs?

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Virtually everyone in the dietary supplement/nutraceutical industry is aware that cranberry has an extensive history of use for treating urinary tract infections (UTIs). Furthermore, this traditional use of cranberry for UTIs has been extensively validated through scientific research. What is lesser known is that there is research supporting cranberry’s benefits for age-related cognitive decline, benign prostatic hyperplasia, and elevated blood pressure. This article will review cranberry’s role in these various benefits.

UTI

UTIs are commonly caused by the gram-negative bacteria Escherichia coli (E. coli) and usually occur when bacteria enter the opening of the urethra (the tube that transports urine from the bladder to the outside of the body) and multiply in the urinary system. Cranberries appear to exert their effect when their naturally occurring proanthocyanidins (PACs) “wrap” around E. coli, preventing them from attaching to the walls of the bladder¹—in which case they won’t be able to cause a UTI or continue causing problems.

Meta-analyses^2,3 of clinical trials with otherwise healthy females at an increased risk for UTIs, or those with a history of recurrent UTIs, found that cranberry products (including juice, capsules, and tablets) decreased the overall risk of recurrent or first-time UTI by 26%-33%. Another meta-analysis⁴ showed that cranberry products decreased the risk of UTI recurrence by 35% in females with a recent history of UTIs. Most studies^5-9 showing positive benefits utilized oral cranberry extracts in tablet or capsule form.

Age-Related Cognitive Decline

In a 12-week parallel, randomized, placebo-controlled clinical trial¹⁰, healthy adults aged 50-80 years used 4.5 g twice daily of freeze-dried cranberry powder (standardized to provide 281 mg of proanthocyanidins daily). This was provided as a sachet and added to food or beverage for 12 weeks. The results were that cranberry improved visual episodic memory performance during a memory and recall test (Rey–Osterrieth Complex Figure Test), when compared with placebo.

Benign Prostatic Hyperplasia

In a six-month randomized controlled trial¹¹, 42 benign prostatic hyperplasia (BPH) patients (45 years of age or older) with elevated prostate-specific antigen (PSA) levels, a negative prostate biopsy, and clinically confirmed non-bacterial prostatitis were given 1500 mg (500 mg, three times/day) of powdered dried cranberry fruit. Results were that, compared to control, subjects using cranberry had statistically significant improvement in International Prostate Symptom Score; quality of life; urination parameters, including voiding parameters (rate of urine flow, average flow, total volume, and post-void residual urine volume); and lower total PSA. Cranberry improved lower urinary symptoms and reduced PSA levels.

In another double-blind, randomized, placebo-controlled study¹², 125 men over 45 years of age with lower urinary tract symptoms but without elevated PSA received 250-500 mg/day of a dried cranberry powder for six months. Results were that the cranberry reduced lower urinary tract symptoms and improved voiding and storage symptoms when compared with placebo.

Elevated Blood Pressure

A meta-analysis¹³ of 10 clinical studies found that cranberry juice or cranberry extract reduced systolic blood pressure by 3.6 mmHg and body mass index by 0.3 kg/m² when compared with placebo. The reduction was more pronounced in studies with subjects whose age were ≥50 years. Also, subgroup analysis suggested a significant increase in high-density lipoprotein concentrations in subgroups with subjects <50 years.

A randomized, placebo-controlled, crossover trial¹⁴ in patients who were overweight or obese and had elevated blood pressure found that drinking 250 ml of cranberry juice twice daily for eight weeks reduced ambulatory diastolic blood pressure by 2 mmHg during daytime hours compared with placebo.

Conclusion

Human clinical research indicates that cranberry products may help decrease risk of recurrent/first-time UTIs, improve visual episodic memory performance, improve BPH symptoms, and lower systolic blood pressure.

References

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2. Wang, C.H.; Fang, C.C.; Chen, N.C.; et al. Cranberry-containing products for prevention of urinary tract infections in susceptible populations: a systematic review and meta-analysis of randomized controlled trials. Arch Intern Med. 2012, 172 (13), 988-996. DOI: 10.1001/archinternmed.2012.3004
3. Fu, Z.; Liska, D.; Talan, D.; Chung, M. Cranberry reduces the risk of urinary tract infection recurrence in otherwise healthy women: a systematic review and meta-analysis. J Nutr. 2017, 147 (12), 2282-2288. DOI: 10.3945/jn.117.254961
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6. Mazokopakis, E.E.; Karefilakis, C.M.; Starakis, I.K. Efficacy of cranberry capsules in prevention of urinary tract infections in postmenopausal women. J Altern Complement Med.2009, 15 (11), 1155. DOI: 10.1089/acm.2009.0240
7. Stothers, L. A randomized trial to evaluate effectiveness and cost effectiveness of naturopathic cranberry products as prophylaxis against urinary tract infection in women. Can J Urol. 2022, 9 (33), 1558-1562. https://pubmed.ncbi.nlm.nih.gov/12121581/
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9. Singh, I.; Gautam, L.K.; Kaur, I.R. Effect of oral cranberry extract (standardized proanthocyanidin-A) in patients with recurrent UTI by pathogenic E. coli: a randomized placebo-controlled clinical research study. Int Urol Nephrol. 2016, 48 (9), 1379-1386. DOI: 10.1007/s11255-016-1342-8
10. Flanagan, E.; Cameron, D.; Sobhan, R.; et al. Chronic consumption of cranberries (Vaccinium macrocarpon) for 12 weeks improves episodic memory and regional brain perfusion in healthy older adults: a randomised, placebo-controlled, parallel–groups feasibility study. Front Nutr. Published online May 19, 2022. DOI: 10.3389/fnut.2022.849902
11. Vidlar A.; Vostalova, J.; Ulrichova, J.; et al. The effectiveness of dried cranberries (Vaccinium macrocarpon) in men with lower urinary tract symptoms. Br J Nutr. 2010, 104 (8). DOI: 10.1017/S0007114510002059
12. Vidlar, A.; Student Jr., V.; Vostalova, J.; et al. Cranberry fruit powder (Flowens) improves lower urinary tract symptoms in men: a double-blind, randomized, placebo-controlled study. World J Urol. 2017, 35 (4), 419-424. DOI: 10.1007/s00345-016-1896-1
13. Pourmasoumi, M.; Hadi, A.; Najafgholizadeh, A.; Joukar, F.; Mansour-Ghanaei, F. The effects of cranberry on cardiovascular metabolic risk factors: a systematic review and meta-analysis. Clin Nutr. 2020, 39 (3), 774-788. DOI: 10.1016/j.clnu.2019.04.003
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