Research is supporting cranberry’s benefits for age-related cognitive decline, benign prostatic hyperplasia, and elevated blood pressure.
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.
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-analyses2,3 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 studies5-9 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.
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.