Cranberries were traditionally used by Native Americans for kidney and bladder infections, but recent research has found they are less helpful than previously thought.

Cranberries (Vaccinium macrocarpon) were traditionally used by Native Americans for kidney and bladder infections. They contain a substance that can prevent bacteria such as E. coli from sticking to the walls of the bladder and urinary tract.
What is it used for?

Mainly preventing and treating urinary tract infections (UTIs); urinary deodorising in nursing homes.
How is it used?

Cranberries are consumed as juice or made into extracts, teas, or over-the-counter supplements.

Scientific evidence?

It was previously thought that there was good scientific evidence that cranberries (juice, extract or capsules) can help prevent urinary tract infections in women.

However a large review published in 2012 looked at newer studies together with the older evidence and found that cranberries are not as effective as previously thought. The authors of the review said that given any benefit from cranberries (juice, tablets or capsules) is so small, they can’t be recommended for preventing UTIs.

Meanwhile there is still no high quality evidence that cranberry juice or other cranberry products are useful in treating UTIs.

Further studies will help clarify the usefulness of cranberries in preventing and treating UTIs.

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https://www.abc.net.au/health/library/stories/2014/04/04/3974980.htm