D-mannose is a simple sugar that comes from mannitol which is produced from fructose, starch or sucrose from certain fruits, vegetables, plants and trees and some marine plants such as kelp. However you should only consider using D-mannose at the very beginning of symptoms. If symptoms have not diminished or completely disappeared after a short period, do not wait any longer and go to the doctor. There is a risk that bacteria are growing at a faster rate than can be cleared through D-mannose especially if the bacteria are resistant to it. There is also insufficient research at present to demonstrate D-mannose’s overall efficacy in treating recurrent and persistent cystitis.

It is found in cranberries, apples and other fruits such as gooseberries and blackcurrants. It is also present in smaller quantities in aloe vera, green beans, tomatoes, cabbage, root vegetables such as turnips. Think of it as a natural, simple sugar that is related to glucose.

However the body absorbs mannose much more slowly than glucose and does not convert it to glycogen (glycogen is the stored form of glucose) or store it in the liver. Only very small amounts of D-mannose are metabolized (processed by our digestive system), so it doesn’t interfere with blood sugar regulation. This enables D-mannose to be quickly absorbed into the bloodstream (in under an hour), through the kidneys and then excreted in urine out of the body. It is an important sugar when it comes to health and is found in most cells in the human body including that of the bladder wall (urothelium).

Why is there a link between D-mannose and the treatment of urinary tract infections?

While many bacteria can cause a UTI, the most common pathogen for both uncomplicated and complicated UTI is gram-negative uro-pathogenic Escherichia coli (E. coli) or UPEC. UPEC are responsible for 80%–90% of all uncomplicated UTI and approximately 65% of complicated UTIs.1

Most E-coli strains live harmlessly in the the gut of humans and animals such as cattle, pigs, sheep and poultry. Strains of E-coli, as part of the gut flora, play a part in the digestive process.

UPEC can be shed in your stools, allowing them to live on the perineum or the urogenital area (the vulva and vaginal/urethral entrances). This can lead to bacteria being introduced into the urinary tract.

Upon entering the bladder, these infection causing bacteria must ensure they are able to bind to the bladder lining and/or a surface such as a catheter to establish and develop a bacterial colony. To do this, UPEC species change shape and develop adhesive pili (or hairs) on their surface. These are known as Type 1 FimH (or Fimbria) and it is these that allow these bacteria to stick and thus begin to establish colonies. Think of them as grappling hooks. During bacterial colonization, these grappling hooks bind to carbohydrate‐containing protein receptors found in the cells of the bladder wall and effective bacterial colonies can develop as these receptors provide the right nutrients for growth.

As first mentioned, mannose is found in cells all over the body including the bladder wall. UPEC love the D-mannose in these cell walls because of their glucose element allowing them to attach and replicate.

If a catheter is introduced into the bladder, fibres can develop across the surface of the catheter caused, it is thought, by the inflammatory immune system response of the body from which fibres leak into the bladder and are deposited onto the catheter. This allows UPEC to bind to the catheter and promotes growth of the infection.

D-mannose molecules in the urine may act as a competitor to the mannose cells on the bladder wall lining for bacteria as they are similar in structure and may prevent colonisation of a catheter surface via pili attachment to the fibres. The key is the dosage of D-Mannose. In sufficient concentration in the urine, if the D-Mannose is effective, the bacteria can be expelled from the bladder by urination. Any remaining infectious bacterial cells in the urine can be tackled by your immune system with the introduction of bacteria killing white blood cells and the shedding of the infected bladder wall cells to prevent re-establishment and growth.

Should D-mannose be used each time a UTI develops or to help prevent recurrent infections?

Current research available has shown that:

  • D-mannose may be effective for the reduction of acute or recurrent infections if taken at the very onset of the infection when symptoms are first noticed.
  • D-mannose may be effective against certain strains of E-coli or possibly Klebsiella known to cause UTIs to prevent bacterial attachment to the bladder wall.
  • D-mannose is a natural alternative remedy that may be used if the user does not wish to use daily prophylaxis or low-dose antibiotics to prevent acute infection or reinfection. Increasing bacterial resistance to low dose antibiotics has meant that many front-line antibiotics such as Trimethoprim are now resistant to strains of UPEC.
  • D-Mannose will not affect either the vaginal microbiome or urinary microbiome unlike antibiotics. The use of these can lead to thrush/candida.

The case against

However, there is insufficient, current research at present to demonstrate D-mannose’s overall efficacy in treating recurrent and persistent cystitis. Issues include:

Issues with D Mannose:

How will D-mannose help with a chronic embedded intracellular or biofilm infection?

Usage of D-mannose for penetration of a biofilm or an intracellular infection would not be effective. Where it may be of use is for acute attacks, when these cells release planktonic (active) bacteria into the urine and you experience a ‘flare up’ of symptoms. By using D-mannose at sufficient dosage, this may help to prevent reinfection and new colonies of infection being created on the bladder wall. But it will only work if the bacteria identified are UPEC.

Should I keep using it?

If you have used D-mannose before and found it effective previously then it is your choice as to whether you continue using it to manage an acute UTI or as a preventative.

A teaspoon of D-mannose should ideally contain around 2,000 mg of pure Mannose and a single tablet or capsule should have around 500mg. Your health practitioner should offer guidance as to the appropriate dosage.

The following points should help.

How to use D Mannose

Types of D-mannose

Powder or Capsules and understanding D-Mannose formulations

What is research now focusing on based on the behaviour of UPEC to D-mannose?

The Hultgren laboratory at the Department of Molecular Microbiology, Washington University School of Medicine in the US is now focusing on inhibitors of UPEC bacteria to attachment of the bladder wall. One area of development are mannosides. Mannosides are mannose replicates that are designed to bind with FimH and thus block UPEC from attaching to the bladder wall. Murine (or mice) studies have shown that mannosides are potent, fast acting and highly efficacious in the treatment of UTI and also catheter induced UTI (known as CAUTI). One study they have produced notes: “Mannoside treatment is especially promising as a novel antibiotic sparing therapeutic because they are effective against multi-drug resistant uropathogens. While D-Mannose and mannosides both appear to effectively block FimH-mannose interactions, mannosides have approximately a 1,000,000-fold increase in potency for inhibiting FimH, making them promising antibiotic-sparing therapeutics.” 2

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D Mannose further reading and references