Reader Mr. Liu used the "Contact Me" of this website on July 16, 2020 to inquire:
Hello, Professor, I am a loyal reader of the Gui website. I am very grateful to the professor for sharing the knowledge related to medical studies through the perspective of scientific verification. I took the liberty to ask a professor for a question, because my female friends have had repeated urinary infections recently, and some people asked doctors for help in treating antibiotics. However, the process of searching for data on the Internet has seen many health foods that add cranberry to prevent urinary tract infections, and some have also seen articles saying that mannose is effective. My friend also wanted to try this information because she would have trouble getting stomach upset when taking antibiotics, so she wanted to take the liberty to ask a professor if she could write an article on these two ingredients. Thank you Professor!!!
There are certain scientific reasons for the use of cranberries and mannose to prevent or treat urinary tract infections, especially the papers on cranberries, which are still very large.
Cranberries are used to prevent urinary tract infections as a folk method that has a history of at least a century, and their mechanism of action was believed to be due to the strong acid contained in cranberries that can prevent bacterial infections in the urinary tract. However, in a 1989 communication paper, it was first suggested that the A-type proanthocyanidins contained in cranberries should be compounds that can effectively inhibit the adhesion of bacteria (Boscium melanin) to the urinary tract. This discussion is still the most widely accepted.
There are many types of cranberry juice on the market and different ingredients, so it is not suitable for clinical trials. This is why the American Institute of Health created a standardized cranberry juice in 2003 and a corresponding soothing agent, and two years later this combination was used for a random double-blind clinical trial. The results published in 2012 show that people who drink cranberry juice have fewer urinary tract infections than those who drink comforters, although the difference does not achieve a statistically significant meaning.
The experimental results failed to achieve a statistically significant meaning, perhaps because the amount of active ingredients contained in cranberry juice was too low, so a new clinical trial switched to a dense cranberry capsule, and the results were confirmed to be a significant difference in the statistically significant. Please read the 2015 article.
However, a clinical trial paper published in 2016 stated that using cranberry capsules does not reduce the incidence of urinary tract infections. So, until now, there is still no discussion on whether cranberries (whether it is juice, capsules, or other forms) can prevent urinary tract infection.
There are three related medical associations (Urology Association in the United States, Urology Association in Canada, Urology, Urology, and Urology Reconstruction Association in Women) in a 2019 joint release guide that based on C-level evidence (low certainty), doctors can recommend cranberry products for women with recurrent urinary tract infections.
Mannose is a monosaccharide with a chemical structure similar to glucose, and it is widely present in various animals, plants and microorganisms. Although mannose is important for our physiological actions, we do not need to take mannose from foods because our bodies can convert glucose to mannose or mannose to glucose.
Too much mannose is excreted from the urine, and because the structure of mannose is similar to the binding site of the urothelial glycoprotein receptor, it is a competitive inhibitor of bacterial adhesion. When the concentration of mannose in the urine reaches the appropriate level, it causes the adhesion of bacteria, thereby preventing bacteria from attaching to urothelial cells. This mechanism has been supported by animal experiments, but so far, clinical trials still cannot determine whether mannose can prevent urinary tract infections. There are two main reasons: (1) Different experiments use different doses or different schedules, and (2) Most experiments use multiple prescriptions, rather than just mannose. This is because of this variation that the results of the comprehensive analysis cannot achieve the significant meaning in science. Please read a summary article published in 2019.
In that 2019 co-published guide, mannose was not recommended. In other words, cranberries are already very low, but mannose is still lower. Therefore, readers of Mr. Liu’s friends may be able to try these two methods, but it will work, and I am not sure whether it will be effective.
Original text: cranberry, mannose, urinary tract infection