Cranberry concentrate comes in liquid form suitable for mixing with water and in tablets manufactured from cranberry extract. Both forms of the fruit are used as a botanical treatment to prevent urinary tract infections. Cranberry concentrate may be sweetened or unsweetened, and some products need refrigeration if preservatives have not been added.
Both cranberry extract and cranberry concentrate measure high in salicylic acid, the main substance found in aspirin. It might help prevent blood clots and reduce inflammation in swollen tissues. Cranberries also might increase the absorption of vitamin B12 and permit the kidneys to metabolize antidepressant drugs at a faster rate. These factors might change the effectiveness of some prescription and over-the-counter drugs.
Most research using cranberry concentrate has focused on preventing re-occurring urinary tract infections, especially in elderly patients. Scientists believe cranberries block certain bacteria from attaching to cells in the urinary system. Effectiveness is deemed moderate, but studies found no use for cranberry concentrate to cure or ease symptoms of urinary tract infections once they exist.
A 2009 study of patients with spinal cord injuries showed significant improvement in the number of urinary tract infections over a one-year period. These infections represent a common reason for hospitalization in patients who live with spinal cord damage. Researchers found cranberries comparable to antibiotics in preventing urinary tract infections and promoting healthy urinary tract functioning.
Cranberry concentrate is considered generally safe to use, except in extremely large quantities. The long-term effects of the fruit are not known. Diarrhea and upset stomach have been reported by some patients using substantial doses of this alternative medicine.
One adverse reaction might be the formation of kidney stones in people with a history of the disorder. Cranberry concentrate contains high levels of the chemical oxalate. Oxalate and calcium represent substances in kidney stones. Researchers found people using cranberry juice to prevent infection tested higher in oxalate, calcium, sodium, and phosphate. Urine samples also tested high in magnesium and potassium, two minerals that inhibit the growth of kidney stones, making the study inconclusive.
Although not backed by science, some people suffering type 2 diabetes use cranberry products to lower blood sugar. Other uses include treating pleurisy, chronic fatigue syndrome, and scurvy. Some patients report healing properties when cranberries are applied to the skin.
Cranberries grow in bogs and belong to the same family of plants as bilberries and blueberries. Documented reports going back centuries show cranberries as a treatment for cancer, blood disorders, scurvy, and excessive vomiting. Native Americans used the fruit to treat bladder and kidney disorders before modern science began studying the berries. Early settlers in the United States first called the fruit craneberry because the berry and stem reminded them of the bird.