Genuinely useful for urinary tract infections — as long as it is not the sweetened juice.
Cranberries have one of the better-supported specific claims in the fruit world:
proanthocyanidins in cranberry appear to reduce recurrent urinary tract infections in women
prone to them.
The catch is enormous. Most cranberry juice on shelves is heavily
sweetened, because raw cranberries are almost inedibly tart. A sweetened cranberry drink is
mostly sugar water with a little cranberry, and it does not deliver the benefit
meaningfully.
Unsweetened cranberry juice, dried cranberries without added sugar, or
whole frozen cranberries are the useful forms.
Per 100g fresh. Sweetened dried cranberries are a completely different nutritional product.
Based on the nutrients and fibre this food supplies. These are supporting foods, not treatments.
Read the label on juice. "Cranberry juice cocktail" is mostly sugar. Look
for 100% juice or unsweetened.
Dried cranberries are usually
sweetened — often heavily. Unsweetened versions exist and are very
tart.
Frozen whole cranberries keep for months and work in cooking
year-round.
It is prevention, not treatment. Cranberry does not treat
an active UTI. If you have one, see a doctor — untreated UTIs can reach the
kidneys.
The active compounds are A-type proanthocyanidins, which appear to interfere with
E. coli's ability to adhere to the bladder wall. Bacteria that cannot attach get flushed
out.
Evidence is reasonable for prevention of recurrent infections in susceptible women
and weak to absent for treating an existing infection. Reviews have been mixed largely because
studies used wildly different products and doses — which is itself the point about
choosing the right form.
Cranberry does not treat an active UTI. See a doctor — untreated
infections can spread to the kidneys.
On warfarin: cranberry may
interact. Tell your doctor.
Kidney stones: cranberry is high in
oxalate and may not suit stone formers.
Diabetes: whole fruit over juice, portion aware, and better eaten
with protein or fat than alone.
IBS: several fruits are high-FODMAP
and commonly trigger symptoms — tolerance is personal.
Kidney
disease: potassium may need limiting. Ask your doctor for your numbers.
This is information, not a prescription. If you are managing a diagnosed condition or taking medication, talk to your doctor before making a large change to your diet.
Nutrition figures on this page come from standard food composition data. These links let you check the numbers and read the underlying research yourself rather than taking our word for it.