The North American variety is used for juices, extracts, capsules and fresh and dried berries. The lingonberry is the Swedish mountain cranberry.
Shop-bought Cranberry juice is usually pure juice diluted with water and sugar added. The sugar content is high and may feed the bacteria thus reducing the effectiveness of the Cranberry.
Unsweetened Cranberry juice is more effective but is bitter, although it can be made more acceptable by adding other fruits such as melon or mango.
Cranberry is a healthy, low-calorie fruit that is widely used to prevent urinary tract infections.
It works by preventing bacteria from sticking to the bladder and urinary tract, so they are washed out.
Its action means that it could be useful in cutting down dental plaque and gum disease.
Cranberry is being investigated for preventing stomach ulcers by stopping the stomach bacteria Helicobacter pylori, which causes ulcers, from getting established.
Cranberry capsules or tablets are more active medicinally than juices. A dose of 400 mg taken twice a day is normal, although up to six 400 mg doses can be taken twice a day if necessary.
If you can find unsweetened Cranberry juice, a dose is usually 15 to 30 ml a day. Or you could take fresh or frozen cranberries (about 40g twice a day).
Large amounts of Cranberry juice can cause diarrhoea and stomach upsets. Remember the high sugar content of some juices can cause tooth decay and blood sugar problems for diabetics.
The evidence is that Cranberry does not successfully treat infections: it prevents them.