The ads claim SuperMannan cures bladder infections. The science is a single uncontrolled study of 9 women; its design is a recipe for disaster.
I was surprised to read that SuperMannan cures bladder infections. I’m a skeptic; I question and proportion my belief to the evidence. I wanted to know more. Who says that? How do they know? Why haven’t I heard about this before? What is it? How could it work? Have there been any controlled clinical studies? Where is the evidence? Have studies compared it to other treatments? Is it as effective as/more effective than other treatments? Are there any side effects? Is it wise to choose it over other options to treat a bladder infection?
I soon learned that the claim is based on an overly generous interpretation of very preliminary research. There may be something there, but the evidence doesn’t currently support recommending it as an effective option in clinical practice.
The SuperMannan website makes strong claims:
- Groundbreaking discovery to promote urinary tract health!
- Testimonial: “Cured forever.”
- a food-based PATENTED discovery, tested for purity, efficacy, safety.
- This isn’t D-Mannose; it isn’t just cranberry; this IS a one-time wonder!
Their website includes lots of testimonials and a tab titled “Read the Science“.
The “Science” tab reports a single study. The lead author is an acupuncturist, which doesn’t inspire confidence. The title is “Yeast Mannan Oligosaccharide Dietary Supplement in the Treatment of Chronically Acute Urinary Tract Infections”. The title doesn’t inspire confidence either: infections are either acute or chronic, not “chronically acute”. I think they meant “recurrent”. The carelessly cited references don’t inspire confidence either: a reference that is supposedly about the complications of antibiotic treatment is actually about the effects of cranberry juice. It references a patent granted to Richard Katz for his discovery of a natural intervention for urinary tract infections in humans. The patent was only for a specific method of administering yeast mannan oligosaccharides; patents do not require and do not constitute evidence of efficacy.
The study design was a recipe for disaster. The subjects were a mere 9 women who were family members and friends of the investigators and who requested access to the product. They had all been diagnosed with recurrent episodes of culture-positive urinary tract infections (UTIs), and their urologists had given them an open prescription for antibiotics to use whenever they had recurrent symptoms of dysuria, frequency, and hematuria. There was no control group and no randomization. It was open-label: the subjects knew what they were taking. They were given SuperMannan, a mixture of three ingredients: two dried, autolyzed yeast products containing yeast mannan oligosaccharides (MOS) and cranberry (which is itself problematic). They were instructed to take 2 capsules followed by 2 additional capsules every 20 minutes for the next 2 hours, and then 2 capsules every 12 hours for the next 24 hours, for a total of 18 capsules in 24 hours.
The results consisted of self-reports by the subjects. All reported relief within an hour and a lower rate of recurrence after treatment (lower than what?). Three of the nine subjects reported “side effects” of urinary urgency without the other symptoms of UTI. They did have the grace to admit that “we do not know at this time whether mild symptoms in the weeks or months following the acute attack were related to E. coli or were irritations without E. coli present.” And they admitted that their results were “preliminary” and only “suggested” a role for SuperMannan, and that their hypotheses should be tested in follow-up randomized trials – they specified randomization but they failed to mention the need for a control group.
They describe (hypothesize) a mechanism by which MOS might act to reduce the ability of E. coli bacteria to infect bladder cells, but the best they can say is that it “likely” metabolizes complex mannosides and “likely” opsonizes the bacteria. This is purely speculation on their part. Their “safety testing” included administering it to a dog for 2 weeks; he experienced no adverse side effects and his digestion reportedly improved.
I won’t bother to list all the flaws that could have led to noise and false-positive results in this study design; I think most readers will be able to spot them for themselves.
Studies of D-mannose
An article in MedicalNewsToday reviewed the research on D-mannose and found it suggestive but insufficient and flawed. They said there is no way to know the appropriate form and dosage to use. And they reported side effects (diarrhea) and a concern that pregnant women or diabetics might experience complications. WebMD concluded “insufficient evidence“.
An article in Reviews in Urology was skeptical and raised concerns that D-mannose might be ineffective or even harmful:
Studies utilizing rodents and human urothelial cell lines have demonstrated that d-mannose-based inhibitors of FimH can block UPEC adhesion and invasion of uroepithelial cells. This basic science evidence has formed the basis for the promotion of d-mannose in human rUTI prevention. However, it is important to note that there are virtually no clinical studies in which d-mannose has been evaluated for rUTI prevention. In fact, there is in vitro evidence that mannose can inhibit macrophage activity, which could theoretically retard bacterial clearance from the urinary tract. Additionally, d- mannose may not be effective against certain strains of UPEC or other uropathogenic bacteria that do not express type 1 pili and FimH.
Effective treatments are available
Science has produced a lot of reliable data about effective treatments for acute UTIs and recurrent UTIs. That information is well summarized in an article in American Family Physician. Research results must be interpreted with caution, keeping in mind that up to one-third of UTIs resolve spontaneously in a week. Overuse of antibiotics is a concern because it can contribute to antibiotic resistance, but that doesn’t justify replacing proven effective treatments with unproven ones. SuperMannan and D-mannose are unproven.
Conclusion: Not convincing
The only evidence for SuperMannan is one very small, very flawed uncontrolled study. The evidence for D-mannose itself isn’t much better: it is preliminary and lacking in human clinical studies. Prudent patients with recurrent UTIs will get their medical advice from science-based health care providers, not from acupuncturists and supplement salesmen.
This article was originally published in the Science-Based Medicine blog.