The Indigenous peoples in North America used cranberries for centuries.
In tribes such as the Ojibwa, Iroquois, and Algonquin cranberries were valued for food, medicinal purposes and red-colored dyes.
Cranberries also immediately became a valued food among American settlers; one of the earliest records of medicinal use was in 1672 by John Josselyn as a protection against scurvy, a scourge of the long sea voyages of the day.
By the mid-19th century, German physicians first provided scientific evidence of the benefits of cranberries to the urinary tract, and by the early 20th century serious research began on the composition and activity of cranberry fruit, identifying for example the presence of anthocyanins.1
After these first science-based inquiries, however, it took almost 100 years of in-depth scientific work to understand how and why cranberry’s unique composition benefited and supported urinary tract health (UTH).
Research discovers cranberry’s unique Anti-Adhesion Activity
In 1984 the first study was published establishing that cranberry’s UTH benefits were unique and their activity was distinct from antibiotics in that they didn’t kill the bacteria causing urinary tract infections, but interfered with the ability of bacteria to adhere to the urinary tract lining, known now as Anti-Adhesion Activity (AAA).2
AAA is particularly significant today as UTIs are the most common outpatient infection in the US. It’s estimated that they cause about 10.5mn doctor’s office visits each year. As most of these cases are caused by bacteria, they are generally treated with lengthy or repeated cycles of antibiotics.
This has resulted in increases in antibiotic resistance that has alarmed health researchers both in the US and the EU.3 Because the AAA of high-grade cranberry extracts doesn’t kill bacteria, but causes them to pass through the urinary tract, there is less chance of selection of resistant bacterial strains.4
Science shows what to look for in UTH cranberry extracts
Though cranberry’s AAA was identified in 1984, it still took over 20 years of research to establish why and how cranberries have this key function. One breakthrough came in 1998 when leading cranberry researcher Amy Howell published a paper that identified the proanthocyanidins (PACs) in cranberry as being the compounds responsible for their unique activity.4
But this still left open a key question: PACs are responsible for the red and purple colors in all fruits, so why do the cranberry PACs have this unique AAA, while PACs from other fruits don’t provide this benefit?
Research continued and this question was answered in two key studies published in 2005 also by Amy Howell and L.Y. Foo. The first identified unique A-Type PACs in cranberry, not present in other fruits. A second study also published in 2005, ‘A-Type cranberry proanthocyanidins and uropathogenic bacteria in anti-adhesion activity’ confirmed these results. The dosage found in these studies to be effective in supporting UTH is 36mg to 72mg/day of A-Type PACs.5
Choosing a cranberry extract tested and standardized for A-Type PACs
There are dozens of cranberry ingredient options available: dried juice concentrates, extracts standardized to total PACs (these often get a high number), and a few extracts standardized for true A-Type PACs, using the accepted BL-DMAC test method.
The true A-Type PAC extracts are expensive to make because cranberry fruit only contains 0.1% to 0.3% of these compounds, so making 1kg of extract standardized to 15% A-Type PACs will often take 150kg to 200kg of fruit that then undergoes a complex extraction process.6
Cranberries with A-Type PACs support women’s health
Ethical Naturals’ (ENI) Cranberex is one of the few extracts from either the US or EU that meets these standards. The company has been supplying the product for over 10 years though its NSF Certified Redwood City, CA facility.
Amy McKelvey, Founder and CEO of Her Vital Way is an industry authority on women’s health and supplies Cranberex through her company. “Cranberex has been Her Vital Way’s leading product for over eight years,” says McKelvey.
“We supply it both direct to end-users and through a network of health practitioners. The feedback we get for both short and long-terms UTH support is exceptionally positive. We’ve always insisted on using this product because it’s one of the few that has absolute guarantees on levels of therapeutic A-Type PACs.”
Clinically-validated cranberry extract
Published studies confirm the activity of cranberry’s A-Type PACs for UTH.1-6 Additionally, another multicentric, randomized study conducted Howell at Rutgers University in 2017, using ENI’s Cranberex clearly affirmed a bacterial anti-adhesion effect in urine based upon a 36mg dosage of cranberry A-Type PAC (tested by DMAC method).7 It also found that effectiveness was dose-dependent, prolonged up to 24 hours with 72mg of PAC.7
”Manufacturing a product like Cranberex, standardized to the active A-Type PACs is complex and requires high concentrations of quality fruit,” says Cal Bewicke, CEO of ENI.
“This strong evidence is why leading companies in both the US and the EU are now bringing this product to their customers. All the work that’s been done on the benefits of cranberry extracts clearly define A-Type PACs as having for the greatest benefit in support of UTH.”
References
- Upton, R.; et al. Cranberry Fruit. American Herbal Pharmacopoeia. 2016.
- Sobota AE. Inhibition of bacterial adherence by cranberry juice: potential use for the treatment of urinary tract infections. J Urol. 1984 May;131(5):1013-6.
- Mareș, C.; et al. Update on Urinary Tract Infection Antibiotic Resistance-A Retrospective Study in Females in Conjunction with Clinical Data. Life (Basel). 2024 Jan 9;14(1):106.
- Jangid, H.; et al. Cranberry-derived bioactives for the prevention and treatment of urinary tract infections: antimicrobial mechanisms and global research trends in nutraceutical applications. Frontiers in Nutrition. 2025; Vol 12.
- Foo, LY.; et al. The structure of cranberry proanthocyanidins which inhibit adherence of uropathogenic P-fimbriated Escherichia coli in vitro. Journal of Natural Products. 2000; 63, 9: 1185-7.
- Howell, AB.; et al. A-type cranberry proanthocyanidins and uropathogenic bacterial anti-adhesion activity. Phytochemistry. 2005 Sep;66(18):2281-91.
- Howell, AB.; Bacterial Anti-Adhesion Activity of Human Urine: Cranberex® (Ethical Naturals). Rutgers University. 2017.
