Natural Products

Cranberry

Vaccinium macrocarpon, oxycoccus quadripetalus

Efficacy

• Indications with proven efficacy:
  None
• Indications with possible, but poorly documented efficacy - the use of this product cannot be recommended:
  Prevention of urinary tract infection
  Urine deodorizer in incontinent individuals
• Also used for these other indications, but with no proof of efficacy:
  Anticarcinogenic agent
  Antipyretic
  Antiseptic
  Diuretic
  Mild acute urinary tract infection

Security

• Risk of Drug Interactions: Low
• Adverse Effects: Rare

What is it?

Cranberry is a well-known small red berry. The juice extracted from its berries is thought to have some medicinal value. The native Amerindians used to consume crushed cranberry berries to prevent and treat urinary tract infections. Cranberry juice is still widely popular today.

Up to recently, it was thought that cranberry's efficacy was due to its urine acidifying property. However, we now know that two substances found in cranberry fruit can inhibit bacterial adhesion to the bladder wall, thereby inhibiting infection. Some other cranberry constituents have been shown to have anticarcinogenic activity, but the clinical significance of this activity has yet to be established.

Cranberry juice (cocktail = 1/3 juice + water + added sugar) is most popular, but cranberry capsules are also available.

Warning

In 2004, Canada adopted new regulations that control the manufacturing, packaging, labeling and importing of natural health products. The new regulations also include an adverse reaction reporting system. Products that conform to the regulation's criteria are identified with a natural product number (NPN) or homeopathic medicine number (DIN-HM) and can be legally sold in Canada. This number indicates that the product meets specific criteria for safety and purity, not that it is effective for any indication.

Medicinal plants content varies naturally from plant to plant – just as fruits from the same package may vary in taste and texture. There is no standard to measure the active content of each plant. Thus, efficacy of natural products should be expected to vary from brand to brand as well as from bottle to bottle of the same brand.

For more information about the Natural Health Products Regulations, or to check if a product has been assessed, visit the Health Canada website at http://www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.

Does it work?

There is evidence that cranberry may prevent urinary tract infections, and is an effective urine deodorizer in incontinent individuals.

• Urine deodorizer in incontinent individuals
  Prevention of urinary tract infection :
  For prevention of urinary tract infection, the typical dose is 90 to 500 mL of cranberry cocktail once a day. It is not known if cranberry capsules are effective but some sources recommend 300 to 400 mg of concentrated cranberry juice capsules twice daily. There is no specific dosage recommendation concerning its use as a urine deodorizer.

There is insufficient reliable information to conclude that cranberry is effective in any other indication.

Is it safe?

• Cranberry is not associated with any specific toxicity. Ingesting large quantities of cranberry juice (3 to 4 liters a day) may result in diarrhea and abdominal cramps. Consuming more than 1 liter per day over a prolonged period of time might increased the risk of kidney stone formation. Sugar content must be kept in mind when cocktail is used.
• Cranberry is likely safe during pregnancy and breast-feeding.
• Peoples taking warfarin (Coumadin) should limit or avoid drinking cranberry juice because of the risk of hemorrhage.

Clinical notes

• Cranberry juice is an option for preventing recurrent urinary tract infections. However, its actual usefulness in the treatment of acute urinary tract infections remains to be established.

References

1. Natural Medicines Comprehensive Database, Therapeutic Research Faculty, 2007
2. Lininger S. and Al. The Natural Pharmacy, Prima Health, 1998
3. Peirce, Andrea. Practical Guide to Natural Medicines, APha, 1999
4. Facts & Comparisons, The Lawrence review of natural products, 1998
5. Passeportsanté.net. Canneberge. http://www.passeportsante.net
6. Barnes J. and Al. Herbal Medicines, 2nd edition, Pharmaceutical Press, 2002
7. McCormack M. and Latouf JB. Les canneberges et la prévention des infections urinaires: mythe ou réalité?, Le Clinicien, December 2003
8. Rotblatt M. and Ziment I. Evidence-Based Herbal Medicine, Hanley & Belfus, 2002
9. Taylor J. CE: Phytomedicinals: Uses, precautions, and drug interactions. Drug Topics 2003;1:79
10. Current Problems in Pharmacovigilance, Medicines and Healthcare products Regulatory Agency, September 2003
11. Shields KM. Possible Cranberry and Warfarin Interaction, Pharmacist's letter, No. 191103 November 2003
12. Cranberry for Prevention of Urinary Tract Infections, American Family Physician, December 1, 2004