There are a surprising number of d-mannose benefits that can be gained if you use this supplement wisely.
What is D-Mannose?
D-Mannose sometimes referred to as mannose, is a type of sugar that is naturally produced by your body from glucose. Most people have heard the folk wisdom to drink lots of cranberry juice in order to treat and prevent urinary tract infections, and d-mannose is the reason why. However, cranberry is not the only fruit that is a good source of this simple carbohydrate. Peaches, oranges, apples, and blueberries all also contain a lot of d-mannose. D-mannose commercial supplements are often made with corn or cranberry.
D-mannose is a glyconutrient, a class of molecules that help support cell-to-cell communication. Even though d-mannose is a sugar, unlike glucose, it doesn’t absorb well into the bloodstream. In fact, almost 90% of d-mannose is not absorbed by the body. Because of this, d-mannose may actually lower blood sugar in some patients who are on medications for blood disorders.
The health benefits are listed below.
Urinary Tract Health
One of the benefits of d-mannose not being absorbed well into the bloodstream is that it does what it needs to quickly, and stays localized in the kidney, bladder, and urinary tract. The sugar then exits your body without breaking down in your system. D-mannose supports the lining of your urinary tract and prevents particles from sticking to it. It is also slightly diuretic in nature, helping to flush your system of infection. The body does also produce mannose on its own, and evidence suggests that taking supplemental d-mannose, which raises your blood mannose levels, may then, in turn, boost urinary mannose levels. This can be helpful in preventing urinary tract infections from occurring in the first place. According to a 2014 study published in the World Journal of Urology by Bojana Krancec et al., the use of d-mannose resulted in a significantly lower risk of side effects for women with urinary tract infections, as compared to a pharmaceutical solution, nitrofurantoin. 
Because of how it locally targets the urinary system, d-mannose is primarily used to treat painful urinary tract infections. Urinary tract infections are very common, with one in five women experiencing them multiple times in their lives. The symptoms include burning and irritation during urination, lower abdominal pain, and bloody or cloudy urine.
As d-mannose passes through your system, it coats the sides of the bladder and urinary tract with sugars that stop bacteria from attaching to the walls. It also promotes the growth of Tamm Horsfall Protein (THP ), the most abundant protein in the urine that naturally binds to bacteria.
Most urinary tract infections are caused by E.coli bacteria, and d-mannose is specifically effective against E.coli, flushing out a significant amount of related infections in only a day. For this reason, it is usually recommended primarily as an alternative antibiotic to treat urinary tract infections. Some people prefer to avoid prescribed antibiotics, as they can kill off friendly microorganisms as well, throwing off your body’s balance and leading to an increased risk of yeast infections. A 2013 Croatian study showed D-mannose may work just as well as antibiotics, without killing off the helpful flora in your gut.
D-mannose may be prebiotic,  which means it supports and promotes the growth of healthy gut bacteria. The healthy gut microbiome has been linked to improved weight management, cardiovascular health, blood sugar regulation, and positive effects on a variety of other diseases.
D-mannose may also help bind and block lectins in your gastrointestinal system. Lectins are a type of protein found in beans, grains, seeds, and some vegetables and fruits. They are difficult for the body to digest, since they are not broken down by stomach acid, and can cause irritation if they are eaten raw. D-mannose binds to lectins, helping the system flush them out through urination.
Carbohydrate-Deficient Glycoprotein Syndrome Type 1b
Carbohydrate-Deficient Glycoprotein Syndrome Type 1b is an inherited genetic disease that stops the protein from being absorbed in the intestines. D-mannose may help  stop this protein loss and encourage healthy liver function. It may also prevent blood disorders and regulate blood sugar in people with this disease.
Common Mistakes with D-Mannose Dosage
When taking d-mannose supplements for a UTI, there are a few common mistakes that cut down on the nutrient’s effectiveness:
- Drinking Too Much Water: Too much water will dilute the supplement, meaning that the d-mannose doesn’t have enough time to sit in the urinary tract before being flushed away. Drink your dose with only half a glass of water for maximum effectiveness, wait thirty minutes, and then drink more water to encourage urination.
- Take It at the First Sign of Infection: Take d-mannose at the earliest sign of infection to stop bacteria from building up.
- Keep a Doctor on Speed Dial: D-mannose will usually clear up a small infection within 1-2 days. If your UTI persists, it’s important to see a doctor soon, in order to prevent the infection from getting serious and moving into your kidneys.
- Side effects of d-mannose can include diarrhea and bloating.
- High doses may also cause kidney damage.
- Patients with diabetes should not take d-mannose because it may interfere with their medications, or make it difficult to regulate their blood sugar.
Before adding this supplement to your regular routine, it is best to speak with a trained professional about your health concerns and strategies.