Cranberries (Vaccinium Macrocarpon) Are Indigenous

cranberries (Vaccinium macrocarpon) are indigenous to North America and have been used in traditional Native American medicine for centuries if not millennia. Related to blueberries and rhododendrons, the North American cranberry is a bog fruit commonly used as a culinary fruit. However, the small berries and leaves of the cranberry plant have also been used in traditional medicine for a multitude of purposes including "wounds, urinary disorders, diarrhea, diabetes, stomach ailments, and liver problems," (NCCAM). Scientific investigations into the medicinal benefits of cranberries have been mostly inconclusive, although like most fruits the cranberry does contain vitamins, minerals, and antioxidants and is fully safe (Natural Standard Research Collaboration 2006).

Cranberries have attracted the attention of researchers because of their potential use as a prevention for urinary tract infections. Research does seem to support the cranberry's role in preventing urinary tract infections because the fruit contains "chemicals that prevent bacteria from sticking to urinary tract cells," (Mirkin). Moreover, Mirkin writes for Quackwatch, an online resource dedicated to debunking medical myths and clarifying misleading information about natural and alternative medicine. The National Center for Complementary and Alternative Medicine (NCCAM) echoes Mirkin's claim "that components found in cranberry may prevent bacteria, such as E. coli, from clinging to the cells along the walls of the urinary tract and causing infection." However, the mechanism(s) by which this is possible has yet to be fully understood and more research is necessary if medical science is to embrace the cranberry either as a preventative or curative food.

A recent study may help explain more specifically why cranberries have been shown to minimize the adherence of bacteria to uroepithelial cells. Liu, Gallardo-Moreno, Pinzon-Arango, Reynolds, Rogriguez, & Camesano (2008) that found that "cranberry juice disrupts bacterial ligand-UC receptor binding." A study by Liu, Black, Caron & Camesano (2006) demonstrated "molecular-level changes in the surfaces of P-fimbriated E. coli upon exposure to neutralized cranberry juice." In other words, cranberry juice affects bacterial adhesion at the molecular level.

The ability of cranberry to inhibit bacterial adherence has been studied for decades and offers researchers the most promising evidence that cranberries do offer significant medical benefits. As early as 1984, research revealed the anti-bacterial adherence properties of the bog fruit. Prior to the 1980s, most researchers hypothesized that the potential for cranberries to prevent urinary tract infection was due to urine acidification. However, the theory that acid/alkaline theory of disease has since been robustly debunked (Mirkin). Sobota (1984) found that cranberry juice significantly inhibited bacterial adherence.

Most studies on the effects of cranberries on bacterial adherence use cranberry juice cocktails, and not pure extracted cranberries. Future research should use pure cranberries or a standardized extract to ensure valid results and also to minimize the effect of contaminating variables especially the higher sugar content in cranberry juice cocktails than in plain juice or a standardized extract. Isolating which types of bacteria cranberries inhibit adhesion of in addition to E. Coli would also boost research validity. Researchers may also want to discover whether cranberries are more effective for anti-bacterial adhesion under specific conditions and whether those effects extend beyond their application to the urinary tract.

Raz, Chazan, & Dan (2004) isolated two compounds with antiadherence properties in cranberries, especially as they "prevent fimbriated Escherichia coli from adhering to uroepithelial cells in the urinary tract." Moreover, the Raz et al. (2004) study used several experimental groups each using different cranberry products including capsules and juice concentrate. Another study by Greenberg, Newmann & Howell (2005) shows that cranberries indeed do contain special antibacterial adhesion properties that other fruits do not. In the Greenberg et al. (2005) study, the researchers compared dried cranberries to dried raisins and found that participants who consumed a single serving of dried sweetened cranberries elicited bacterial antiadhesion, based on urine samples, versus participants who consumed the same amount of raisins. Furthermore, the Greenberg et al. research reveals that cranberries in dried form may be every bit as effective as they are in juice form.

A slew of similar studies reveal promising results: cranberries may be used as what the Food and Drug Administration (FDA) classifies as a "medical food." A medical food is defined by the Orphan Drug Act as "a food which is formulated to be consumed or administered...under the supervision of a physician and which is intended for the specific dietary management of a disease or condition for which distinctive nutritional requirements, based on recognized scientific principles, are established by medical evaluation," (FDA). Moreover, when a food like cranberry is defined as a medical food it must be standardized: its compounds isolated and processed into manageable and regular dosages.

With a vested interest in the success of cranberries as a medical food, the Cranberry Institute cites preliminary research testing the anti-carcinogenic properties of cranberries: "human breast cancer cells showed significantly lower incidence of tumor development when the experimental group's diet was supplemented with cranberries." Cranberries have been irresponsibly touted for a wide range of conditions including "anti-aging," a claim clearly not substantiated by medical research (the Cranberry Institute). The most plausible use of cranberries for health and well-being is for urinary tract infections.

Further research into the properties of the cranberry includes investigations into the potential for the cranberry to prevent the formation of dental plaque and to prevent certain types of cancer (NCCAM). Because of the promising results of studies investigating the ability of cranberries to prevent bacterial adhesion, research into bacterial infections other than urinary tract infections is pending. Some preliminary studies hypothesize an effect of cranberries on preventing Helicobacter pylori (H. Pylori), the bacteria most commonly a culprit in stomach ulcers as well as dental plaque. Preliminary research on the effects of cranberries on oral hygiene show possible uses for the fruit in mouthwashes (the Cranberry Institute). Yet most studies so far have either been inconclusive or too small to yield reliable results except for those that show both in vivo and in vitro effects of cranberries on bacterial adhesion. Most research on the effects of cranberries on H. Pylori has been in vitro.

A suggested use of cranberries to prevent heart disease is also not substantiated by evidence. According to the Cranberry Institute, the flavonoids found in cranberries "have been shown to function as potent antioxidants both in vitro and in vivo and may reduce the risk of atherosclerosis." However, research by Duthie, Jenkinson, Crozier, Mullen, Pirie, Kyle, Yap, Christen, & Duthie (2006) showed no effect of cranberry juice consumption on "blood or cellular antioxidant status or several biomarkers of lipid status pertinent to heart disease," and no effect "on basal or induced oxidative DNA damage." The authors conclude that in vivo and in vitro test results can differ significantly (Duthie et al. 2006). Too often, an alternative or complementary medicine will be touted irresponsibly, without being supported by a sufficient or reliable body of scientific research.