(June, 2013) Whether in dried fruit, juices, jams, sauces, capsules or chewing gum, the American cranberry [Vaccinium macrocarpon] benefits human health in numerous ways. Best known for its salutary effects on urinary tract health (16, 25), cranberry has also shown promise in nutritional support against cancer (23), heart disease (28,30), neurologic disorders [Alzheimer’s; Parkinson’s] (19), and infectious diseases (24). Unlike drugs, cranberry is safe for human consumption, even in high amounts (3, 13).
Most intriguing is cranberry’s ability to keep bacteria from sticking to surfaces. Bacteria have developed many ways to latch on to virtually any surface. That’s because there are advantages to staying put and forming cooperative communities. Once attached, bacteria form a slimy substance called biofilm, such as in dental plaque, that glues the community together.
Biofilms are everywhere. They line the digestive tract, especially the lower intestines, and all skin surfaces. Healthy biofilms may contain hundreds of different bacterial species working together to benefit humans. In health, nearly 100 trillion organisms protect us from pathogens and toxins, help boost immune defenses, keep our plumbing working, keep us from getting fat, and may even help us think better (27,29). An imbalance of bacteria in the gut – particularly from antibiotic usage – leaves us susceptible to disease.
There are many harmful biofilms as well. They are implicated in a whopping 65-80% of all human bacterial infections, according to the CDC and NIH (32). Biofilms initiate infections in the ear, nose, mouth, lungs, gut, and urinary tract, to name a few. They also glom onto medical and indwelling devices, such as urinary catheters, stents, and prosthetic implants. Biofilms are often opportunistic, flourishing when immune defenses are down. They may stay under the radar to produce chronic, low-grade infections, such as sinusitis, tooth decay, gingivitis, or chronic urinary tract infection. Alternatively, biofilms can lead to full-blown, deadly infections, such as kidney disease or pneumonia. Periodontitis is a more severe biofilm infection of the gums beyond gingivitis. Biofilm formation is a key virulence factor for pathogenic bacteria in diverse environments (17).
The slimy polysaccharides that keep the biofilm together form a protective layer to shield bacteria from antibiotics and immune defenses. Like Jello, biofilm holds on to water to help bacteria survive dry periods. It also scavenges minerals for growth and structural purposes. An older biofilm accumulates calcium and other minerals to become hardened, like the calculus that forms on teeth. Biofilms often persist, despite aggressive antimicrobial treatment. Eliminating biofilms often requires a heavy, protracted regimen of antibiotics, mechanical debridement (e.g., tooth brushing, wound cleaning), or removal of a contaminated medical device (12).
Oral diseases, from cavities to oral cancer, cause pain and disability for millions of Americans. Dental caries and periodontal disease affect up to 90% of the world population, and are all biofilm related. Over 500 species of bacteria can be found in the mouth; some helpful and some not. Bleeding gums allow these bacteria to enter the bloodstream, linking oral infection to systemic problems like cardiovascular disease, diabetes and other disorders (4, 18, 26). Proper oral hygiene and periodontal treatments reduced pneumonia up to 40% among hospitalized patients (31). As a rule, oral health is a good barometer for health in general.
Both dental plaque and gingivitis (red, swollen, bleeding gums) involve biofilms, on the teeth and near the gums, respectively. Nearly half of all children have had tooth decay, and one-fourth of U.S. elderly are without teeth. Gingivitis affects 50-90% of adults worldwide. In the U.S., over 80% of adolescents suffer from gingivitis (2), and one-eighth of American adults have moderate to severe periodontal disease (1). In 2010, roughly $108 billion was spent in the U.S. on dental services, including 500 million dental visits (11).
The red pigments in cranberries have been shown to inhibit biofilm formation. These proanthocyanidins [PACs] are the most abundant phytochemicals extracted from cranberry fruit, and have been reported to possess antimicrobial, anti-adhesion, antioxidant, and anti-inflammatory properties (6). These unique flavonoids may play an important preventive role in oral infections (9, 14). Like Teflon, they prevent the attachment of pathogens to host tissues, and can inhibit the formation of biofilms in the mouth (22). Cranberry PACs inhibited adherence and biofilm formation by Porphyromonas gingivalis, a bacterium associated with gum disease, and markedly reduced its invasiveness (21). PACs reduced the proliferation and destructive activities not only of P. gingivalis, but also other pathogens in periodontal pockets (5, 8, 20). They also prevented adherence and biofilm formation by Candida albicans, the causative agent of thrush and many yeast infections (15).
By inhibiting attachment and biofilm formation, cranberry PACs prevent destruction of connective tissue in the gums. They also neutralize enzymes that destroy gum tissue. An extract from cranberry juice inhibited tissue-destroying enzymes made by bacteria (21) and humans (7), even at the lowest concentration tested [10 mcg/mL]. PACs also inhibit the production of inflammatory chemicals [i.e., IL-6, IL-8, prostaglandin E2] produced by host cells (8). These cranberry-induced processes help protect against bone loss and promote gum integrity (14, 20). Regular use of cranberry PACs would serve to reduce antibiotic use, and help prevent bacterial resistance to antibiotics (14).
Cranberry PACs also prevented sugar-dependent biofilm formation on teeth (dental plaque) by the bacterium Streptococcus mutans, the major cause of tooth decay. They do so by inhibiting biofilm-forming enzymes (33), and keeping bacteria from aggregating (34, 36). One human trial showed that daily use of a cranberry-containing mouthwash for 6 weeks significantly reduced levels of mutans streptococci in saliva (35). Protecting against cavities and tooth decay – despite consumption of sugary foods – would have an enormous impact on oral health in children and adults.
Clearly, cranberry may be useful for the management of several biofilm-related diseases, including tooth decay and gum disease in the mouth, stomach ulcers (10), and urinary tract infections. As a fruit extract, it does so in a safe and pleasant manner. The impact of daily use of cranberry PACs on health care costs and quality of life is likely to be substantial.
References available upon request