Cranberry

Common Names: cranberry, American cranberry, bearberry

Latin Names: Vaccinium macrocarpon (also known as Oxycoccus macrocarpos), Vaccinium oxycoccos

Background

Cranberry is an evergreen shrub that thrives in wet environments, particularly in the North Central and Northeastern regions of North America. It has a long history of traditional use in dyes, food, and medicine among Native Americans and later European settlers. The fruits and leaves of the cranberry plant were believed to have therapeutic effects on disorders of the bladder, stomach, blood, and liver, as well as on various conditions like wounds, diabetes, and scurvy.

Cranberry is commonly promoted today for the prevention and treatment of urinary tract infections (UTIs) and recurrent UTIs. Cranberry products are recommended for these common infections in part due to the growing interest in nonantibiotic prevention strategies, especially given concerns about antibiotic-resistant bacteria.

How Much Do We Know?

Numerous studies have been conducted on cranberry for the prevention of UTIs, particularly in women who are at increased risk for UTIs or recurrent UTIs. However, some of the research lacks high quality. Studies on the use of cranberry for other conditions are scarce.

What Have We Learned?

In general, cranberry products may reduce the overall risk of symptomatic, recurrent UTIs in women by 25 percent, and in some cases, by more than 30 percent. However, the effectiveness of cranberry remains in question due to inconsistent findings. While cranberry may assist in preventing symptomatic UTIs in some women, it is not recommended as a treatment for existing UTIs in any population.

It is thought that proanthocyanidins (PACs) in cranberries prevent bacteria from sticking to the bladder wall, thus preventing the onset of a UTI. Processing cranberries into various products like tablets or capsules can reduce the concentration of PACs, which in turn may reduce the potential effectiveness of a product.

Studies in certain populations at increased risk for UTIs, such as elderly people in long-term care and pregnant women, have yielded inconsistent results. Research in other high-risk populations, such as women undergoing gynecological surgeries or people with multiple sclerosis, has not shown cranberry to be beneficial in reducing the risk of UTIs.

Starting in 2020, the U.S. Food and Drug Administration (FDA) has allowed manufacturers to claim on product labels that there is "limited" evidence that daily consumption of specified amounts of cranberry dietary supplements may lower the risk of recurrent UTIs in healthy women. A similar claim can be made for cranberry juice beverages, although the evidence is considered "inconsistent and limited."

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What Do We Know About Safety?

Cranberry taken by mouth is generally considered safe. However, consuming very large amounts of cranberry may cause stomach upset and diarrhea, particularly in young children. Individuals who suspect they have a UTI should seek a health care provider for diagnosis and treatment. Cranberry products should not be used in place of proven UTI treatments.

The evidence on whether cranberry interacts with the anticoagulant (blood thinner) warfarin is conflicting. If you take warfarin or any other medication, it is important to consult your health care provider before using cranberry or other herbal products, as some herbs and medications may interact in harmful ways.

Dear Lykkers, some studies on the use of cranberry during pregnancy or breastfeeding suggest it is safe in amounts typically found in food, but the evidence is not conclusive for larger amounts. If you are considering using cranberry while pregnant or breastfeeding, it is advised to consult your health care provider.

Keep in Mind

Take control of your health by discussing any complementary health approaches you use with your healthcare providers. Together, you can make informed decisions.

Federal Regulation of Herbal Products

Depending on what's in them, how they're intended to be used, and how they're administered (by mouth or topically), herbal products are regulated in various ways. Many herbal products intended for digest are marketed as dietary supplements. The regulations for manufacturing and distributing dietary supplements are less stringent than those for pharmaceuticals.

Unlike drugs, dietary supplements do not require FDA approval before being sold to the public. If public health concerns emerge regarding the safety of a dietary supplement or its ingredients, the FDA has the authority to take action to safeguard the public. Manufacturers and distributors of supplements are responsible for evaluating the safety and labeling of their products before marketing them to ensure they meet all regulatory requirements.