Gunter Haesaerts, the founder of Pharmatoka and the man who in 2004 convinced French authorities of the cranberry’s PACs (proanthocyanidins)-based UTI potential and won a world-first health claim, said the trials commissioned by some juice makers were asking for trouble due to bad design.
“The juice producers are now paying the price for not having clearly quantified and qualified the active PAC ingredient in the products they sell and occasionally supplied for the clinical trials,” said Haesaerts.
Cochrane systematic review considered 14 additional studies that caused it to reverse its 2008 finding that found UTI benefits associated with cranberry juice, especially for women with recurrent UTIs if drunk over a 12-month period.
The University of Stirling’s Ruth Jepson said: “...the majority of existing studies indicate that the benefit is small at best, and the studies have high drop-out rates [up to 55%]."
Other problems plagued the assessed studies, Haesaerts said.
“Researchers routinely use uncharacterised, non-standardised ingredients without knowledge of the basics of cranberry PAC science, resulting in products that may not have sufficient bioactivity to be beneficial."
“This combined with weak study protocols and implementation has led to inconclusive results in many cases. What is at stake here is not the cranberry PACs, but the appalling lack of rigor in the clinical studies.”
“The many ‘juice studies’ that went wrong for many reasons do not negate the strong scientific support in favour of cranberry for urinary tract health.”
Haesaerts noted the French Government Agencies for Food and Medicines Security (ANSES) has validated 36mg per day cranberry PACs claims five times between 2004 and 2011, but few studies achieve the 36mg/day level.
The European Food Safety Authority (EFSA) has also dismissed similar claims.
The dosage issue was acknowledged by Jepson who said levels needed to be clear to warrant further research in tablets and capsules, if not juices.
For the updated systematic review, the team gathered together evidence from 24 studies – involving a total of 4,473 people.
After publication, David Tournay, owner of cranberry player, Tournay Biotechnologies (acquired this month by Nexira), got in touch to add: "The fact that many of the cranberry juices that are available in stores now are blended with other fruits, or do not contain enough cranberry concentrate, may lead to less active products, and consumers probably need to be cautious on this issue."
"Cranberry supplements, on the other hand, seem to attract more and more loyal consumers who think that extracts are more likely to be the best choice, in terms of easiness of use, consistency of quality and efficacy."