D Mannose is a simple sugar molecule. D mannose can be used safely and has few side effects if ingested in small amounts.

D Mannose for urinary tract infection
D Mannose has been found to be helpful in preventing bladder infections.

D-Mannose supplement for purchase
Buy D-Mannose supplement

Mannose -binding plant lectins
Mannose-binding lectin (MBL), a serum protein characterized by both collagenous regions and lectin domains, plays an important role in innate immune defense. It binds to the repeating sugar arrays on many microbial surfaces through multiple lectin domains and, following binding, is able to activate the complement system via an associated serum protease, MASP-2.

D-Mannose side effects
Q. On your website regarding d-mannose you state that it has few side effects. Could you enlarge on this and advise what are the side effects. I read that it can be useful for bladder infections so I purchased some and dissolved 1/2 teaspoon in a glass of water and drank it. I did not have a bladder infection and wanted to evaluate its results for use next time I do because I do not like to rely on antibiotics when it happens. Shortly thereafter I started to have severe irritation in my bladder and urethra. I don't know whether it was due to the d-mannose but feel that is a good possibility because it was alleviated by taking pyridium. The pain is constant and does not become worse with urination so I doubt it is cystitis. Today is the third day I have had this problem although I did not take any more D-mannose. I have looked up the MSDS for Mannose and it does mention skin irritation. Also eye irritation which I had yesterday but not today.
   A. This is the first report we have had of possible d mannose side effects. Which d mannose product was it? Did it have other ingredients?
      Q. It is the NOW Foods brand. Apparently it has no other ingredients. The info on the package says "Technically known as D-Mannose, this is a simple six-carbon sugar. Mannose is a stereoisomer that is a mirror image of Glucose and naturally occurs as a monosaccharide (simple sugar) in fruit like blueberries and cranberries, as well as in other plants and fungi. NOW Foods pure Mannose is derived from corn, white and sweet potatoes, beech or birch woods and has a caloric value (similar to other sugars) of four calories per gram. Mannose exists in two forms - alpha and beta. The alpha form is mild and sweet, while the beta form is bitter. The natural manufacturing methods for Mannose results in a mixture of these two forms; yielding a product that is mildly sweet with a slight bitter aftertaste."

D Mannose Research study
Mannose binding plant lectins: different structural scaffolds for a common sugar-recognition process.
Biochimie. 2001 Jul;83(7):645-51.
Mannose-specific lectins are widely distributed in higher plants and are believed to play a role in recognition of high-mannose type glycans of foreign micro-organisms or plant predators. Structural studies have demonstrated that the mannose-binding specificity of lectins is mediated by distinct structural scaffolds. The mannose/glucose-specific legume (e.g., Con A, pea lectin) exhibit the canonical twelve-stranded beta-sandwich structure. In contrast to legume lectins that interact with both mannose and glucose, the monocot mannose-binding lectins (e.g., the Galanthus nivalis agglutinin or GNA from bulbs) react exclusively with mannose and mannose-containing N-glycans. These lectins possess a beta-prism structure. More recently, an increasing number of mannose-specific lectins structurally related to jacalin (e.g., the lectins from the Jerusalem artichoke, banana or rice), which also exhibit a beta-prism organization, were characterized. Jacalin itself was re-defined as a polyspecific lectin which, in addition to galactose, also interacts with mannose and mannose-containing glycans. Finally the B-chain of the type II RIP of iris, which has the same beta-prism structure as all other members of the ricin-B family, interacts specifically with mannose and galactose. This structural diversity associated with the specific recognition of high-mannose type glycans highlights the importance of mannose-specific lectins as recognition molecules in higher plants.

D Mannose supplement questions
Q. I just found out about D-Mannose for UTI. Have you researched this?
   A. We don't have experience using it with patients, but D mannose supplements may be a promising nutrient for urinary tract infections.

Thank you for sharing your knowledge. Your website is very informative. What is the effect of D-Mannose on yeast overgrowth in the gut?
    I have not seen such research, so I don't know.