Cranberry

• RawFruitInternalClinical trial

  Prevention of recurrent uncomplicated urinary tract infections (cystitis). The 2023 Cochrane review found moderate-certainty evidence that cranberry products reduce the risk of repeat infections - especially in women with recurrent UTIs, in children and in people particularly susceptible. The effect is modest and not universal; in the healthy general population or in elderly care-home residents the benefit is unclear. The European authority EFSA rejected a corresponding health claim for lack of an established cause-and-effect relationship.

  Preparation & dosage

  To help prevent recurrent uncomplicated urinary tract infections, drink about 240-300 ml of unsweetened cranberry juice daily or take a standardised dry extract (often adjusted to about 36 mg proanthocyanidins per day). This is a preventive, not an acute treatment: in an active bladder infection - especially with fever, flank pain or blood in the urine - cranberry is no substitute for doctor-prescribed antibiotics. The benefit builds up over weeks and is not equally pronounced in everyone.

  Liquid amount

  240–300 ml

  Doses per day

  2×

  Sources: [1] [3] [4]

• RawFruitInternalTraditional use

  Use as a food and source of vitamin C. Traditionally processed into sauce and juice in North America (classically served with the Thanksgiving turkey).

  Preparation & dosage

  Fresh or processed cranberries (e.g. as juice, sauce or dried) provide vitamin C, organic acids and polyphenols. Because of their very tart taste they are usually sweetened or combined with other fruits; dried commercial products are often heavily sugared. Large volumes of juice mean correspondingly high sugar and calorie intake.

  Sources: [4] [5]

As a food, cranberry is generally well tolerated. It is, however, NO substitute for antibiotics in an acute or febrile urinary tract infection - medical treatment is required in that case. Cranberries are rich in oxalic acid; caution is advised in people prone to calcium-oxalate kidney stones. Large amounts of juice provide a lot of sugar and calories and may cause gastrointestinal upset. An interaction with the anticoagulant warfarin (possible rise in INR) has historically been described; the evidence is weak, but caution and INR monitoring are nonetheless advisable when warfarin is taken concurrently.