What is a urinary tract infection or UTI?
The urinary tract is the name given to the organs in the body which produce and store urine; the kidneys, the ureters, the bladder, and the urethra. Urinary tract infections (UTIs) occur when bacteria, usually from faeces, enter the urethra, travel upwards and stick to the walls of the urinary tract, where they multiply.
Surprisingly, urine is normally sterile, in other words it does not contain many bacteria at all. The combination of a healthy immune system, specific personal care practices and the flow of urine flushing bacteria out keeps it that way.
When the body detects the presence of bacteria in the "wrong place" it responds by activating the immune system to try and destroy them. Unfortunately, this causes inflammation at the place where our bodies are fighting the invaders, which means that the area becomes swollen and sensitive. This causes pain in the urinary tract, especially during urination. Cystitis is another word commonly used to refer to a UTI.
How might blackcurrants help to stop me getting a UTI?
Drinking a lot of blackcurrant juice or squash may help to prevent UTIs, simply because drinking lots of any fluid means that the urinary tract is regularly flushed out!
Whilst the best treatment for a UTI is a course of antibiotics, many people use plants with antibiotic properties to help prevent the infections. Although the most famous of these is the cranberry, scientists are beginning to think that the blackcurrant may be just as beneficial.
In the laboratory, scientists looked at why cranberries were effective against foreign bacteria in the urinary tract and discovered that substances called proanthocyanidins from cranberries and blueberries stop bacteria from sticking to the walls of the tract, preventing them from remaining there and causing infection (a).
Blackcurrants may also get rid of bacteria from the urinary tract, because they too contain proanthocyanidins (b), which can be found in urine after drinking blackcurrant juice (c).
Furthermore, blackcurrant juice, blackcurrant extracts and single substances from blackcurrants have been tested in the laboratory and were found to stop the growth of some species of harmful bacteria (d).
In a preliminary study on humans, blackcurrant juice was given to elderly volunteers in a nursing home, and was effective in relieving some of the symptoms of a UTI (e).
Interestingly, infection by Staphylococcus aureus (MRSA), a gastroenteritis bug, has been shown to lead to other illness such as UTI (f), but blackcurrant wins again since scientists have recently shown that it is extremely effective at killing this bacteria (g). There can be few other fruit capable of giving such a broad spectrum of benefits!
a. (Bibliography Ref: 86, 87, 88, + (Howell AB, Vorsa N, Marderosian AD, et al: Inhibition of the adherence of P-fimbriated Escherichia coli to uroepithelial cells surfaces by proanthocyanidin extracts from cranberries. N Engl J Med 339: 10851086, 1998). This has recently be corroborated in a clinical study which highlighted the ability of proanthocyanidins to inhibit the growth of a wide range of uropathogenic E. Coli (P. Di Martino, R. Agniel, K. David, C. Templer, J. L. Gaillard, P. Denys and H. Botto. (2006) Reduction of Escherichia coli adherence to uroepithelial bladder cells after consumption of cranberry juice: a double-blind randomized placebo-controlled cross-over trial. World Journal of Urology, 24(1), 21-27.)
b. Another type of polyphenol
c. Bibliography Ref: 89, 90
d. Bibliography Ref: 91, 92, 93
e. Bibliography Ref: 94
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g. R. Puupponen-Pimia, L. Nohynek, S. Hartmann-Schmidlin, M. Kahkonen, M. Heinonen, K. Maa tta-Riihinen and K.-M. Oksman-Caldentey. Berry phenolics selectively inhibit the growth of intestinal pathogens. Journal of Applied Microbiology 2005, 98, 9911000
- Ahuja, S., Kaack, B. and Roberts, J. Loss of fimbrial adhesion with the addition of Vaccinium macrocarpon to the growth medium of p-fimbriated E. coil. Journal of Urology, 1998. 159: 559-562.
- Fowler, J.E. Urinary tract infections in women. Urological Clinics of North America, 1986. 13(4): 673-683.
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- Netzel et al Bioactive anthocyanins detected in human urine after ingestion of blackcurrant juice. J Environ Pathol Toxicol Oncol. 2001; 20 (2): 89-95
- Rechner et al The metabolism of dietary polyphenols and the relevance to circulating levels of conjugated metabolites. Free Radic Res. 2002 Nov;36 (11) : 1229-41
- Puupponen-Pimia R, Nohynek L, Meier C, Kahkonen M, Heinonen M, Hopia A, Oksman-Caldentey K-M. Antimicrobial properties of phenolic compounds from berries. J Appl Microb 2001 90: 494-50
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- Rauha J-P, Remes S, Heinonen M, Hopia A, Kahkonen M, Kujala T, Pihlaja K, Vuorela H, Vuorela P. Antimicrobial effects of Finnish plant extracts containing flavonoids and other phenolic compounds. Int. J. Food Microb. 2000 56:3-12
- L. Boyle et al. 1996, Study of use of blackcurrant juice in nursing home residents to alleviate urinary infection and associated problems. Centre for Ageing Studies, Flinders University of South Australia.