Since the early 1990s researchers have been studying the effects of cranberry juice products on urinary tract health. More recently, researchers have examined cranberries’ ability to promote heart health. Today researchers around the world are studying other potential health benefits of cranberries. While much of this research is preliminary, it is exciting to consider the possible benefits of this humble little red berry.
Based on research showing cranberries contain proanthocyanidins (PACs), substances that interfere with bacteria’s ability to attach to cells lining the bladder walls, researchers in Canada and Japan have been investigating the effects of cranberry extracts on bacteria that cause tooth decay and gum disease. (1-4) These tissue and cell culture studies have shown promising results; cranberry extracts weaken the ability of bacteria to attach to teeth and gums. Does eating cranberries or drinking cranberry juice have this effect? We don’t know yet because human studies have not been performed; however, the anti-adhesion effect of cranberry juice products has been demonstrated for urinary tract health. It is likely that cranberry products have a similar benefit for dental health.
Cancer Prevention & Treatment
According to the National Cancer Institute, diets rich in fruits and vegetables may reduce the risk of some types of cancer and other chronic diseases. One of the reasons why this may be true is that fruits and vegetables contain antioxidants, substances that protect cells from DNA damage and other “injuries” that can increase risk of cancer and other chronic diseases.
A large USDA study of the antioxidant content of more than 1,100 foods showed that cranberries are among the top five foods with the highest antioxidant content per serving. (5) Cranberries contain a number of substances with antioxidant activity, including anthocyanins, flavonols, and proanthocyanidins. These substances reduce oxidative stress, decrease cellular inflammation, and protect DNA, thereby reducing risk of cellular changes that could lead to cancer initiation and progression. (6)
In addition to potentially reducing risk of cancer, cranberries are also being investigated as a way to improve the effectiveness of chemotherapy for ovarian cancer. (7) Researchers at Rutgers University demonstrated in cell culture studies that human ovary cancer cells resistant to platinum chemotherapy drugs became up to six times more sensitized to the drugs after exposure to the cranberry compounds compared to cells that were not exposed to the compounds, which were obtained from juice extracts. The researchers believe the A-type proanthocyanidins (PACs) that are unique to cranberries bind to and block certain tumor promoter proteins found in the ovary cancer cells, making the cancer cells become more vulnerable to attack from the drugs. This study is very preliminary. Further research is needed to confirm these findings, and to determine if the same benefit is seen in women undergoing chemotherapy for ovarian cancer. What is seen in cell studies is not always replicated in human studies.
Stomach ulcers are caused by a type of bacteria called Helicobacter pylori. Studies (8, 9) suggest that cranberry products may reduce the incidence of stomach ulcers the same way cranberries promote urinary tract health and oral health; proanthocyanidins (PACs) in cranberries interfere with the bacteria’s ability to attach, in this case, to the stomach wall. As of May 2008, only one double-blind, randomized, controlled clinical study on humans has been published. (10) All subjects in this study were taking oral antibiotics, and all subjects who received antibiotics plus cranberry juice had lower levels of bacteria in their stomachs. Only women receiving cranberry juice plus antibiotics had statistically significant decreases in bacteria. Further research is needed to determine if this finding was a fluke or if women receive a greater benefit than men.References
- Yamanka A, Kouchi T, Kasai K, Kato T, Ishihara K, Okuda K. Inihibitory effect of cranberry polyphenol on biofilm formation and cysteine proteases of porphyromonas gingivalis. J Periodontal Res. 2007; 42(6):589-92
- Labrecque J, Bodet C, Chandad F, Grenier D. Effects of a high-molecular-weight cranberry fraction on growth, biofilm formation and adherence of Porphyromonas gingivalis. J Antimicrob Chemother. 2006 Aug;58(2):439-43
- Bodet C, Chandad F, Grenier D. Anti-inflammatory activity of a high-molecular-weight cranberry fraction on macrophages stimulated by lipopolysaccharides from periodontopathogens. J Dent Res. 2006 Mar;85(3):235-9.
- Bodet C, Piche M, Chandad F, Grenier D. Inhibition of periodontopathogen-derived proteolytic enzymes by a high-molecular-weight fraction isolated from cranberry. J Antimicrob Chemother. 2006 Apr;57(4):685-90. Epub 2006 Feb 10.
- Halvorsen, BL, Carlsen MH, Phillips KM, Bohn, SK, Holte K, Jacobs DR, and Blomhoff R. Content of redox-active compounds (ie antioxidants) in foods consumed in the United States. Am J Clin Nutr 2006;84:95-135. Full article available at http://www.ajcn.org/cgi/reprint/84/1/95
- Neto CC. Cranberry and blueberry: evidence for protective effects against cancer and vascular diseases. Mol Nut Food Res. 2007;51(6):653-64.
- Singh AP, Vorsa N. Cranberries may improve therapy for ovarian cancer. (unpublished data) Poster presentation at 2007 American Chemical Society meeting, Boston, MA.
- Gotteland M., Brunser O, Cruchet S. Systematic review: Are probiotics useful in controlling gastric colonization by Helicobacter pylori? Aliment Pharmacol Ther. 2006 Apr 15;23(8):1077-86.
- Johnson-White B, Buquo L, Zeinali M, Ligler FS. Prevention of nonspecific bacterial cell adhesion in immunoassays by use of cranberry juice. Anal Chem. 2006 Feb 1;78(3):853-7.
- Shmuely H, Yahav J, Samra Z, Chodick G, Koren R, Niv Y, Ofek I. Effect of cranberry juice on eradication of Helicobacter pylori in patients treated with antibiotics and a proton pump inhibitor. Mol Nutr Food Res. 2007; 51(6):746-51.