Cranberries and UTIs

Some early studies suggested that drinking cranberry juice could reduce recurrent UTIs. However, more recent higher quality research from 2012 found that there is no benefit in preventing UTIs compared to placebo or no treatment. This study was a review of 24 studies with 4473 participants and was carried out by the Cochrane Database of Systematic Reviews, which is a gold-standard level of research. Other findings were that:

• many people in the studies stopped drinking the juice, suggesting that it may be unacceptable to consume in the long term for many people
• cranberry-derived products (such as tablets or capsules) were also ineffective. 

There have been two further randomised trials in 2016. One found no benefit in nursing home residents. Another study found a meaningless benefit of preventing one UTI per 3.2 years of daily drinking of cranberry juice, and the study had significant biases like being funded by a cranberry product manufacturer.

The risk of using cranberry juice is small but includes:

• increased sugar and calories in your diet
• gastrointestinal upset, such as heartburn and diarrhoea
• theoretical risk of kidney stones (high levels of oxalates).

• No single concentration of cranberry juice, extract or supplement has been studied, so it's hard to know which product to choose.
• If you do want to try cranberry juice to prevent UTIs, it's better to drink pure, unsweetened cranberry juice (rather than sweetened cranberry juice). However, many women complain of the taste of unsweetened cranberry juice.
• Using cranberry products to prevent UTIs may be expensive.
• Cranberries may interact with some medicines, such as warfarin and/or aspirin.
• Cranberry juice is not well tolerated long term by many people.

Cranberry products (juice, tablets, or capsules) are not routinely recommended to reduce the incidence of recurrent UTI. Although it is generally safe and there are theoretical reasons for a benefit, clinical studies have not definitively shown a reduction in UTIs.