Cranberries, which are native to North America, have been used since pre-Colombian times as both food and medicine. Native Americans introduced the earliest European settlers to the berries, and the first commercial fields were planted in the early 1800s. Today, cranberries are available as fresh or dried fruit, in juices and in capsule form. A lot of recent research has focused on the medicinal properties of the cranberry, or Vaccinium macrocarpon, and especially its effect on the urinary system, which includes the kidneys and bladder and the tubes that connect them.
Causes and Treatment of Kidney Failure
Kidney failure, also known as kidney disease or renal failure, can be acute or chronic. According to Medline Plus, it affects more than 2 out of every 1,000 people in the U.S. The most common causes are diabetes and high blood pressure. As kidney function declines, it becomes harder for them to filter wastes from your body. These wastes build up in the blood stream, causing fatigue, headaches, loss of appetite, weight loss and itching. You need a blood test to confirm a diagnosis of kidney failure. Kidney failure is a serious condition, requiring physician supervision. You may also require prescription medicines to treat accompanying conditions such as high blood pressure, and careful monitoring of your diet. While cranberry juice can be a part of your diet, it does not prevent or cure kidney failure.
Cranberry Juice and Urinary Tract Infection
While cranberry juice won't cure kidney disease, it has been found to prevent urinary tract infections, or UTIs. People have long thought that drinking cranberry juice would cure UTIs by changing the acidity of your urine. While research has debunked this notion, recent studies do indicate that a specific phytonutrient found only in cranberry juice keeps certain bacteria from sticking to the wall of your bladder or urinary tract tubes, thus preventing an infection. Cranberry juice does not, unfortunately, loosen bacteria that have already adhered to these surfaces, so the bacteria grow, and the resulting infection causes a burning sensation when you urinate. When this happens, you need to consult your doctor. The usual treatment is an antibiotic.
Cranberry Juice and Kidney Stones
Kidney stones form when there is too much uric acid or calcium in your urine. Most are tiny and are eliminated in your urine, but some are larger and don't easily pass through the urinary tract. If you have one, you'll know it. They cause extreme, continuous pain in the lower back or side, nausea or vomiting, fever and chills and possibly blood in your urine. Cranberry contains a compound called an oxalate, which can increase the risk of forming one of the more common types of kidney stone, though it can help dissolve another, less common type. If you're prone to kidney stones, talk to your physician about including cranberry juice in your diet.
Other Benefits of Cranberries
The same property in cranberry juice that aids in UTI prevention may also help you avoid certain ulcers that are thought to be caused by a specific type of bacteria. Cranberries also have lots of vitamin C and other anti-oxidant properties, so are thought to be beneficial in the fight against heart disease and stroke. Researchers are looking into other health claims, but none has yielded results yet.
Other Risks Associated with Cranberries
Besides the potential for causing kidney stones, cranberry juice tends to thin blood, so you should use it cautiously if you're taking blood-thinning medications such as warfarin. Cranberries contain salicylic acid, which is the active ingredient in aspirin. Like warfarin, aspirin thins the blood, so if you take aspirin regularly, talk to your doctor before adding cranberry to your diet. If you're allergic to aspirin, you may also be allergic to cranberries. Most cranberry juice has a lot of added sugar, so you need to consume it moderately to avoid weight gain.