Self-Help Tips From Dr Sarah Brewer

Cranberries For Urinary Tract Infections (UTI)

cranberries for UTI

Cranberries are one of the most popular natural health remedies to both treat and prevent urinary tract infections, also known as UTI or cystitis. Cranberries contain unique substances, known as PACs, which stop bacteria from sticking to the urinary tract walls. When bacteria cannot stick, they are naturally flushed away and infection is prevented, making cranberry supplements a great alternative to antibiotics for treating uncomplicated urinary infections.

Urinary tract infections

UTIs are the second most common infection (respiratory infections come first). They are more common in women than men, as the distance between the female bladder and the outside world is just 4cm, making it easier for bacteria to invade.

One in two women receive antibiotics for at least one urinary tract infection (UTI) during their life, with a third experiencing their first problems before the age of 24. Typical symptoms of a bladder infection (cystitis) include:

  • Painful urination (dysuria)
  • Frequency (having to keep passing only a small volumes of urine)
  • Urgency (running to the loo)
  • Pain which may be felt in the lower back, pelvis, abdomen or groin
  • Unpleasant smelling urine which may be cloudy or blood-stained.

After the first ‘attack’ at least a quarter of women will experience a recurrence within 6 to 12 months.

In mild cases, only one or two symptoms will occur and these may resolve on their own if you drink plenty of fluids. If the infection is severe, however, you will feel very unwell and complications can occur.

Infection can spread up from the bladder (cystitis) to the kidneys (pyelonephritis) and, if not treated promptly, can cause scarring which makes recurrent infections more likely in the future. Bacteria can also spread into the circulation to cause sepsis with a high fever, sweating and rigors (extreme shivering). In older people, UTIs can lead to confusion and increases the risk of a fall. In one study, 70% of hip fractures in women were found to result from running to the bathroom due to urinary urgency.

Nine out of ten urinary infections are caused by a type of bacteria called E.coli which normally live in the bowel, but can make their way into the bladder.They can be pushed up the urinary outlet (urethra) during sex, for example. This is sometimes referred to as honeymoon cystitis. Research suggests that sexual activity can multiply a woman’s risk of UTI fourteen-fold. Some attacks of cystitis are associated with wearing tight trousers or nylon tights which increase warmth and humidity to encourage bacterial growth.

If you experience recurrent cystitis, you will usually be investigated for conditions such as diabetes, anaemia, kidney stones, scarring or anatomical abnormalities of the urinary system, all of which make urinary infections more likely.

Antibiotics and urinary tract infections

UTIs are becoming increasingly difficult to treat with antibiotics. In the U.S. for example, bacterial resistance to commonly used antibiotics increased by more than 30% between 1999 and 2010. Doctors are therefore increasingly reluctant to prescribe antibiotics for a  ‘simple’, infection as the natural flushing action of the bladder can help an uncomplicated urinary infection resolve on its own – especially if you take cranberry extracts.

In one study, involving 137 women with cystitis, all were given a prescription for antibiotics but asked if they were willing to delay taking antibiotics until they really felt they needed them. Just over a third of women (37%) were willing to do this. A week later, when they were followed up, over half of these hadn’t taken the antibiotics and more than two-thirds reported they were better even though their initial results confirmed that a urinary infection was present when they first saw their doctor.

This study reassured many medics that it is often worth ‘watching and waiting’ before prescribing antibiotics to treat symptoms of painful urination, burning, frequency and urgency. This seems a safe approach as long as the infection is not complicated by fever, worsening lower back or pelvic pain, known urinary tract abnormalities and as long as you don’t have diabetes or a condition that reduces your general immunity. Symptoms in children, pregnant women and the elderly are usually treated with antibiotics, however,  as they are more vulnerable to complications.

Cranberries for urinary infections

As a doctor, I feel those who don’t need initial antibiotics for a urinary infection should be offered an alternative, and cranberries are the most effective option. Cranberries from the peat bogs of North America have been used as a traditional herbal medicine for urinary tract infections (UTIs) for over 100 years.

Cranberry juice and cranberry fruit extracts now have scientific evidence to support their use in preventing and treating urinary infections. What’s more, they do not contribute to antibiotic resistance (as they do not interfere with bacterial growth or metabolism) and can be used together with antibiotics to speed their effectiveness.

Because they taste so sour, it was initially believed that cranberry juice worked by acidifying urine so that bacteria were less able to thrive. At least 7 research studies dating back to the 1950s showed that this is one way in which cranberry juice works. It isn’t the whole story, however, as when the acidity was removed, cranberry juice was still effective in both preventing and treating cystitis symptoms.


By the 1980s, scientists recognised that cranberries contained something else that stopped bacteria sticking to the urinary tract walls. This anti-adhesion activity is now known to result from the presence of a unique type of antioxidant known as A-type proanthocyanidins (PAC).

E.coli bacteria each have between 100 and 400 feeler-like landing gear (fimbriae) which they use to attack to cells lining the urinary tract. Cranberry PACs lock onto the ends of these feelers to block their attachment.

After drinking cranberry juice, or taking cranberry extracts, anti-adhesion activity can be measured in the urine within 2 hours, peaks between 4 and 6 hours, and persists for 8 to 10 hours. This prevents bacteria sticking and building up to form a ‘biofilm’ from which they invade tissues to cause inflammation and pain. Instead, the bacteria are flushed away without causing symptoms.

How effective are cranberry extracts?

Research shows that cranberry extracts, taken regularly, can decrease recurrences of urinary tract infections by 30% to 40% in premenopausal women.

Cranberry extracts were recently used in hospital to see if they could prevent urinary infections following catheterization in women undergoing gynae surgery. They were found to halve the rate of post-operative urinary infections.

And in menopausal women aged 45 and over, researchers have concluded that prescribing antibiotics (trimethoprim) only offers a limited advantage compared with recommending cranberry extracts to prevent UTIs, especially as antibiotics are increasingly associated with bacterial resistance.

In children, cranberry products are also at least as effective as antibiotics in preventing recurrent UTIs although they should always be used under medical supervision as the threshold for prescribing antibiotics in children is lower to prevent complications.

Taking all the evidence into account, there is a strong argument for taking cranberry extracts to prevent recurrent UTIs, and to treat an uncomplicated infection. Always seek medical advice if urinary symptoms occur in children, the elderly, if you are pregnant, have other health issues such as diabetes or reduced immunity, or if you develop worsening symptoms or a fever.

Cranberry dose for urinary infections


The usual suggested dose is:

Cranberry fruit extracts:  500mg daily

Cranberry juice: 300 ml cranberry juice (25% strength) daily

Cranberry juice is naturally sour as it has a similar level of sugar and acidity to lemon juice. To make an acceptable drink, the juice is diluted to around 27% juice concentration, and sweetened to around the same level as apple or grape juice.

Low-sugar versions made with artificial sweeteners are available, too, with no loss of the active PACs.

The best cranberry products

Here are the brands that I recommend as they include proven extracts containing a consistent amount of PACs per dose for the best results.

Ocean Spray products have featured in much of the research into cranberry juice PACs and UTIs. I like the Light Cranberry Classic Juice Drink as it contains no added sugar and, like the rest of the range, is free from artificial colours and flavours.

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Cysticlean 240mg PAC are the highest strength supplements available and are made to a pharmaceutical standard known as GMP.

In a recent pilot study of 30 people with uncomplicated cystitis, 21 were ‘cured’ by treatment with Cysticlean, and only 9 needed the addition of antibiotics to achieve a cure. No adverse effects were reported.

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Have you used cranberry juice or supplements to prevent or treat cystitis? If so, did you find them helpful? If you have any questions or comments, please use the form below and I’ll get back to you as soon as I can.

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Dr Sarah Brewer ex-Medical Director (20 years)
Dr Sarah Brewer MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT, CNHC, Dip IoD qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she gained a master's degree in nutritional medicine from the University of Surrey. Sarah is a registered Medical Doctor, a registered Nutritionist and a registered Nutritional Therapist. She is an award winning author of over 70 popular self-help books and a columnist for Prima magazine. Her debut novel is White Powder Of Gold. Dr Sarah Brewer is a registered medical doctor, nutritionist, nutritional therapist and author of over 70 self-help books.

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