Cranberry

Background

Cranberry is a native evergreen shrub that grows throughout North America.

Historically, cranberry fruits or leaves were used for bladder, stomach, and liver disorders, as well as diabetes, wounds, and other conditions.

Today, cranberry is used as a dietary supplement primarily for urinary tract infections (UTIs).

The berries are used in beverages and food. They are also made into dietary supplements in the form of extracts, powder, capsules, and tablets.

How Much Do We Know?

There have been a lot of studies in people of cranberry for UTIs, but there’s very little high quality recent research on cranberry for other conditions.

What Have We Learned?

There’s mixed evidence that cranberry can help to prevent UTIs.

In a 2016 year-long study of 147 women living in nursing homes, taking two daily cranberry capsules decreased bacteria levels in their urine in the first 6 months of the study, but didn’t decrease their frequency of UTIs over the year of the study, compared to taking a placebo. The two capsules together contained as much proanthocyanidin, a compound that is believed to protect against bacteria, as 20 ounces of cranberry juice.

A 2012 research review of 13 clinical trials suggested that cranberry may help reduce the risk of UTIs in certain groups, including women with recurrent UTIs, children, and people who use cranberry-containing products more than twice daily.

A 2012 research review of 24 clinical trials concluded that cranberry juice and supplements don’t prevent UTIs but many of the studies were poor quality.

Cranberry hasn’t been shown to be effective as a treatment for an existing UTI.

NCCIH-supported research is looking at the possible effects of cranberry on cancer-related anemia and tumor cells.

What Do We Know About Safety?

Drinking cranberry juice appears to be safe, although large amounts can cause stomach upset and may over time increase the risk of kidney stones.

Large doses of cranberry may alter levels of warfarin, an anticoagulant (blood-thinner).

People who think they have a UTI should see a health care provider for a diagnosis and treatment. Don’t use cranberry products in place of proven treatments for infections.

Keep in Mind

Tell all your health care providers about any complementary or integrative health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.

Key References

-NIH