Judging by the massive turnout at Women’s Marches around the world this past January, women’s liberation is clearly back in style. (The movement even has its own signature headgear: those très chic pink caps.) And while it’s gratifying to stand back and marvel at all the oppressions the distaff sex has liberated itself from—the patriarchy, household drudgery, shoulder pads—to tweak a certain marketing slogan from feminism’s second wave, “You’ve got a long way to go, baby.”
Case in point: Women have yet to liberate themselves from urinary tract infections (UTIs), or from the endless courses of antibiotics needed to treat them. But they’re making progress, thanks to research into the cranberry, which has long been something of a folk remedy for when urinary health falters.
Notes Christina Khoo, PhD, director, global research sciences, Ocean Spray Cranberries (Lakeville-Middleboro, MA), “For generations, women have passed down their belief in cranberry’s ability to help prevent urinary tract infections based on their own positive experiences.” What’s different now, she says, is that “more than 50 years of well-documented research has turned this folklore into fact.”
What’s also different is that the cranberry is proving to be an equal-opportunity defender, its functional phenolics and chemical constituents conferring a wide range of health benefits beyond the urinary tract alone. So maybe we can have it all? Cranberry supporters are keen to find out.
UTIs and You
Whether they affect you or not—and if you’re a woman, they probably do—urinary tract infections are serious business. “UTIs are among the most common bacterial infections treated in women, which is why they garner so much interest,” says Cindy Taccini, director of global health communications at Ocean Spray.
According to statistics from the National Institute of Diabetes and Digestive and Kidney Diseases, UTIs are the second-most common type of infection in humans, triggering roughly 8.1 million doctor visits per year. Women are particularly susceptible—thanks in part to their shorter urethras, which hasten bacteria’s trip to the bladder—putting their lifetime risk of getting a UTI north of 50%. Moreover, says Dean Mosca, president, Proprietary Nutritionals Inc. (Kearny, NJ), “Once an individual has had a UTI, the likelihood of having another escalates.”
Prevention is key, he emphasizes, as “antibiotics aren’t a long-term solution, due to the possible development of antibiotic resistance and detrimental effects on good gut bacteria.” A 2014 World Health Organization report on global antibiotic resistance noted that resistance to one of the drug classes most widely used to treat Escherichia coli–caused UTIs—the fluoroquinolones—was already so widespread that, in some parts of the world, the drugs are ineffective in more than 50% of patients. No wonder, Taccini says, that WHO considers antibiotic resistance “one of the greatest challenges to public health today, and one that makes leveraging cranberry’s benefits important.”
That the humble cranberry might bend this curve seems a stretch. But, says Mosca, “Unlike antibiotics, which kill bacteria, cranberry works by changing bacterial structure and preventing adhesion to tissues, providing for effective prevention without the risk of developing antibiotic resistance.”
We know this now, but it took the research community a while to figure out. As far back as the 1700s and 1800s, Mosca says, researchers were already investigating cranberry and seized upon its ability to acidify urine as a possible mode of action—although further research failed to support it. So while cranberry stayed popular for urinary health, “its true mechanism remained a mystery.”
That changed in the early 1980s when research appeared in the Journal of Urology showing that cranberry inhibited E. coli adherence to urinary-tract epithelial cells by 80%, a finding that human clinical trials later confirmed. Subsequent research then focused on cranberry’s condensed tannins— antioxidant flavonoids known as proanthocyanidins, or PACs—as the source of the anti-adhesive effect. “These compounds adhere to the fimbriae of the bacterial surface,” Mosca explains, “thus preventing adhesion to the mucosal lining of the bladder.” And that makes it easier to flush bacteria out with urination. “In 1991,” he says, “this finding was duplicated by Israeli researchers and published in the prestigious New England Journal of Medicine.”
Studies continue to support cranberry’s effectiveness. “The largest clinical trial1 of its kind, published last year in The American Journal of Clinical Nutrition, showed that drinking an 8-oz, or 240-ml, glass of cranberry juice a day reduces symptomatic UTIs by nearly 40% in women with recurrent UTIs, reducing the burden of UTIs and the antibiotic use associated with treating recurrent UTIs,” Khoo notes. “The study showed that 30 courses of antibiotics were avoided in women with symptomatic UTI during the course of the six-month study period.”
And though cranberry PACs “have taken center stage as the cranberry component responsible for its bacteria-blocking benefits,” Khoo continues, scientists are gaining “exciting insights” into other cranberry constituents that contribute to the bacteria-blocking effect, including flavonols and “newly discovered” xyloglucan oligosaccharides. “Researchers now believe cranberry’s ability to block bacteria is due more to its combination of compounds working together than to a single component,” she says. “This unique blend of bioactive components is what makes the cranberry such a powerful fruit.”
And the idea of delivering cranberry’s whole spectrum of benefits via whole-berry ingredients is increasingly popular with cranberry processors and brands, too. Notes Dan Souza, vice president, sales and marketing, and category manager for urinary, cardiovascular, and cognitive health, Naturex-DBS (Sagamore, MA), “What we’ve found is that Nature knows more than we do.” The main lesson he thinks researchers learned in teasing apart different fractions’ benefits is that “the more parts of the cranberry we use in these models, the better results we see. So let’s not try to reinvent the cranberry here. Let’s optimize what Nature made for us.”
- Maki KC et al., “Consumption of a cranberry juice beverage lowered the number of clinical urinary tract infection episodes in women with a recent history of urinary tract infection,” American Journal of Clinical Nutrition, vol. 103, no. 6 (June 2016): 1434-1442
- Cires MJ et al., “The gastrointestinal tract as a key target organ for the health-promoting effects of dietary proanthocyanidins.” Frontiers in Nutrition. Published online January 3, 2017.
- Polewski MA et al., “Ability of cranberry proanthocyanidins in combination with a probiotic formulation to inhibit in vitro invasion of gut epithelial cells by extra-intestinal pathogenic E. coli,” Journal of Functional Foods, vol. 25 (August 2016): 123-134