You probably think of cranberries as the zingy accompaniment to your Thanksgiving turkey, but cranberries are a powerhouse all their own and deserve our attention year-round. Cranberries are native to the United States and Canada. They were used extensively by Native Americans as food, medicine, in ceremony and even as a natural dye. Early American settlers also quickly learned their value and used them not just as food but also to prevent scurvy and for a variety of conditions such as stomach ailments, fever, liver problems, swollen glands, and mumps.1 Today the United States still grows the majority of the cranberries in the world and modern research continues to validate their use as both food and medicine.

In addition to being a good source of vitamin C, cranberries, like their cousin the blueberry, are a rich source of antioxidants. Cranberries are one of the highest fruit sources of phenols (a family of potent antioxidants), and one study found they contain more antioxidant activity than broccoli.2 Wide varieties of antioxidants are found in cranberries and these compounds are believed to be responsible for many of the health benefits attributed to these dark red berries.

Urinary Tract Benefits

Very early on, cranberry became known for its ability to support the health of the urinary tract. The proanthyocyanidin compounds as well as the simple sugar d-mannose, which are abundant in cranberries, are believed to prevent pathogenic bacteria in the urinary tract from binding to the mucosal lining.3 If these bacteria are unable to get a foothold in the mucosa, they cannot cause infection. Because of this, cranberry has been found to be effective at reducing the occurrence of urinary tract infections. Other compounds found in cranberries may acidify the urine, which can prevent the formation of certain types of kidney stones (calcium phosphate and struvite stones), but due to cranberry’s high oxalate content, some types of kidney stones may actually be worsened by cranberry.4,5

Cardiovascular Benefits

Cranberries contain many antioxidants that have been shown to have a particular affinity for protecting the cardiovascular system, such as proanthocyanidins, the often-touted compounds in red wine. The antioxidants in cranberries appear to help protect LDL cholesterol from oxidation, help keep the blood flowing smoothly, modulate blood pressure and help to modulate inflammation.6,7

Immune Support Benefits

Recent studies have found that compounds in cranberries interfere with the flu virus’ ability to replicate and establish an infection, in addition to reducing the symptoms of the flu. “Cranberries are incredibly rich in proanthocyanidins, which exert a regulatory effect on human immune cells, priming them to fight off an infection,” Jonathan Clinthorne, PhD, whose doctoral work focused on nutritional immunology, explains. Clinthorne says that these proanthocyanidins seem to be especially beneficial to our immune barriers—the GI tract, the urinary tract, and the mouth. “These are the places where infection can take hold, so if we strengthen these areas, we can prevent viruses and bacterial infections from taking hold in the first place.” The results of one human study support this idea: the proliferation of a specific type of T-cell—an immune cell found in the immune barriers and the first line of defense against infection—was nearly five times higher after 10 weeks of daily consumption of a cranberry beverage.8,9

Researchers have also discovered that cranberry juice can inhibit the norovirus (the dreaded stomach flu) from adhering to human cells, the essential first step in initiating an infection.10 11 Cranberry has been shown to have similar anti-adhering effects on certain types of bacteria, including E. coli and Staphylococcus aureus (staph).12 13

Brain Health Benefits

Cranberries are incredibly rich in a number of health-promoting polyphenols, including proanthocyanidins, anthocyanins, flavonols, and terpenes. One of these terpenes, ursolic acid, was recently found to protect brain cells from excitotoxicity—overactivity of excitatory brain cells receptors, which can damage brain cells and lead to cell death—by significantly reducing oxidative damage to mitochondria. Excitotoxicity is suspected to be involved in both Alzheimer’s and Parkinson’s disease. Cranberries are one of only a few food sources of ursolic acid. Other research has found that the flavonols and anthocyanins in cranberries reduced neuronal cell death caused by oxidative damage by nearly 50 percent, compared to the control. Compounds in cranberries have also been found to exert a strong anti-inflammatory effect.14 15 16

Other Benefits

Cranberry’s ability to prevent bacteria from adhering to the mucosa of the urinary tract has led researchers to speculate about its effects on other types of bacteria in other parts of the body. One place where it appears to be effective is in the stomach for preventing the bacterium Helicobacter pylori from getting a foothold. In several studies, subjects drinking cranberry juice saw decreases in H. pylori populations while they were actively taking it.17,18,19 In test tube studies, constituents and isolates from cranberries show promise even for inhibiting the growth and proliferation of some types of cancers.20,21,22 Although much more research is needed to confirm this potential benefit, this preliminary research does support the notion that the compounds in cranberries are not only potent but have wide-ranging effects throughout the body.

Use and Safety

The most effective way to use cranberry, for most concerns, is as a preventative; i.e., start taking it before you get sick. “Proanthocyanidins only stay in the body for about 6-12 hours, so it should be taken twice daily to maintain consistent levels,” Clinthorne says. Cranberries can be found in pill, tincture, tea, juice, dried and, of course, fresh berry form. Studies using juice generally used three or more ounces of pure cranberry juice or about one and a half ounces of fresh or frozen berries a day.23 Beware that due to their tart taste, most cranberry juices are sweetened either with sugar or other juices, which may not be desirable for many people. Cranberry pills offer a convenient no sugar, no-taste option and usually consist of dried and sometimes concentrated cranberries that have been powdered and encapsulated. For cranberry pills and tinctures dosing information, follow the manufacturer’s directions given on the label. Cranberry is safe for most individuals but in high doses may cause diarrhea or mild gastrointestinal upset. Cranberries also contain oxalates which may be problematic to individuals who are oxalate sensitive. As always, caution should be used when starting any new herb, nutrient, or medication, especially if you are already taking other supplements or medications or have a medical condition.

References Available Upon Request