I received a useful comment from a reader and have decided to pass her suggestion along. She tells me she has had good success in preventing bladder infections by taking d-mannose powder daily. This product was actually somewhat familiar to me from my study of natural medicines several years ago. I decided to do a little research to update my knowledge.
D-mannose is a simple sugar found naturally in apples, oranges, peaches and some berries, including blueberries and cranberries. It may actually be the d-mannose content of cranberries that gives it its ability to prevent bladder infections. Like cranberry, d-mannose works by preventing bacteria from sticking to the bladder walls and starting an infection.
I found a study that compared d-mannose 2 g daily mixed in 200 ml water, with nitrofurantoin 50 mg and no treatment. The effect of d-mannose in reducing recurrence of bladder infection was similar or slightly better than the effect of nitrofurantoin, and both were significantly better than taking no treatment at all. It should be noted that d-mannose only works to prevent infection from e-coli, the bacteria normally present in our anal area that causes an estimated 90% of bladder infections. So, although an infection caused by other types of bacteria could still occur, d-mannose can still make a significant difference in the infection rate.
Other studies, done in mice, suggest that d-mannose is safe to take long-term if taken in appropriate amounts, but excess may cause kidney damage. Side effects may include bloating or loose stools and, if this occurs, reducing the dose would likely reduce these effects.
Caution is recommended in women who are pregnant or breast-feeding — although it is thought by some experts to be safe, being a simple sugar, it has not been studied in these populations. It is also recommended to use caution if you have diabetes, as it may make it harder to control your blood sugar, since it is a sugar. However, as most d-mannose is absorbed more slowly than regular sugan and excreted intact through the urinary system relatively quickly, people with well-controlled diabetes generally do not have any problem, according to other sources. Checking your blood sugar more often when starting this therapy would be advised to alert you to any potential problems.
As an interesting sideline, studies also suggest d-mannose may act as a prebiotic, encouraging growth of “good” bacteria in the digestive system.
The recommended dose of d-mannose for prevention of urinary tract infections, as used in the study, is 2 g (or approximately one teaspoon) once daily in adults, and one half to 1 teaspoon for children, dissolved in a glass of water. Dr. Jonathan Wright, one of the first physicians to begin using d-mannose, claims 85 to 90% effectiveness from this treatment in his patients. D-mannose is available in health food stores and some pharmacies. He also discusses a high success rate in treating active infections with the same dose given every 2 to 3 hours, but cautions that another treatment should be considered if no improvement within 1 to 2 days. I noted that he used an equivalency of 1gram = 1 teaspoonful… Regardless of the actual equivalency, 1 teaspoonful appears to be the dose commonly recommended for adults. Your pharmacist could weigh a sample of the powder for you, if you want to calibrate your 5ml teaspoon from your set at home!
If you decide to stay with cranberry, it is probably best to choose a cranberry concentrate capsule with a high amount of cranberry content (and presumably more d-mannose) rather than the sweetened juice to avoid the increased intake of glucose (sugar) it contains. A price calculation I did several years ago also found high-dose capsules were less expensive than an equivalent amount of juice!
