The sweet and sour of cranberry testing methods

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The sweet and sour of cranberry testing methods

Related tags: Health claim, Cranberry, Urinary tract infection

As Thanksgiving approaches and minds turn to turkey and the trimmings, what better time for the cranberry industry’s main players to agree on a unified method of analysis?

This weekend this Brit will sit down for Thanksgiving dinner with his American girlfriend and an assortment of friends and tuck into turkey and cranberry jelly. Even though I am looking forward to it, thoughts of cranberry leave a sour taste in my mouth as the industry continues to be divided on how best to measure the unique proanthocyanidins (PACs) content of the berries (I admit, I find it difficult to switch off from the day job).

Now is the time for the industry to work together to agree on a method for measuring PACs. That truly would be something to be thankful for.

The A, B, and P-A-Cs of the issue

PACs are not exclusive to cranberries, and can be found in a range of foods, including green tea, grapes, apples, and chocolate. However, the main type of PACs in cranberry called A-type PACs are different from those in these other sources, called B-type PACs. Only cranberry PACs may prevent bacterial adhesion.

In 2004 France became the first country to approve a health claim for the North American cranberry (Vaccinium macrocarpon​) with at least 36 milligrams of PAC to “help reduce the adhesion of certain E. coli bacteria to the urinary tract walls”​, and subsequently fight urinary tract infections (UTIs).

There are several methods for measuring PACs, and they all deliver different results. A neat analogy is measuring temperature with Celsius and Fahrenheit – they both tell you how hot or cold it is, but they don’t give you the same value (unless it’s minus 40, but you’d be too cold to care at that point).

The French health claim refers to 36 milligrams of PACs measured using the 4-dimethylaminocinnamaldehyde (DMAC) method.

Unfortunately the French agency (AFSSA) did not specify which method was valid for the health claim, and this has led to a range of methods being applied, all of which have advantages and disadvantages. But the issue is the not which method is being used, but that if a cranberry-based product is to have a beneficial effect on UTIs it should contain the equivalent ​of 36 milligrams of PACs as measured by DMAC.

If we continue with the status quo then what happens if consumers suffer as products they purchased on the promise of urinary tract benefits do not offer the same efficacy? Answer: They will turn their backs on what they see as underperforming or ineffective products.

Health claims

There was hope from some quarters that EFSA would approve a health claim that specified a method – this would have effectively championed one of the methods above all others. However, you appear to have more chance of being adopted by Warren Buffett and named as his heir than getting a positive opinion on a health claim from EFSA, so that door seems to have closed (two negative opinions have already been issued by EFSA for cranberries and UTIs: It is unknown how the French health claim is affected by these).

So where else could we turn?

We were presented with a potential solution earlier this year. Ronald Prior, PhD, from the US Department of Agriculture’s Agricultural Research Service (USDA-ARS) and a world-leading researcher in all things cranberry, published an improved DMAC method that he hoped would unite the industry – the new method is called the BL-DMAC method (Journal of the Science of Food and Agriculture​, July 2010, Vol. 90, pp. 1473-1478).

“Universal adoption of this standard worldwide by the cranberry industry will allow producers to use one standard method to ensure accurate labelling of PAC levels in products, and aid consumers in selecting products with sufficient PAC levels to obtain bacterial anti-adhesion activity,” ​said Prior in April.

Universal adoption was not forthcoming. The new method for quantifying PACs in the little red berry split the industry like Moses parting the Red Sea.

On one side, the likes of Ocean Spray Cranberries, Decas Botanical Synergies, Lallemand Health Ingredients, and France’s Pharmatoka all welcomed the method as an advance.

On the other side is EuraCran, the European Association for the Valorization of Cranberry Extracts, which questioned the method’s reproducibility, and said that the European Pharmacopoeia method is the best compromise.

Consistency and transparency

To re-iterate, I’m not saying either method is right or wrong, but the results do differ, so it’s about ensuring consistency: If you want to benefit from the French claim, then a product should contain the equivalent of 36 milligrams of PACs as measured using the same method as the studies on which AFSSA based its claim.

If we can’t agree on which method to use, why not use four or five and list all the results? Transparency will help everyone.

The unique PAC profile of cranberries has offered relief from urinary tract infections for many thousands of consumers, and the potential health benefits of the little red berry are ever increasing. It would be a shame if a lack of industry unity turned this sour.

Now, what chance of reaching an agreement before the turkey’s cooked? You’ve got two days: Ready, steady, go!

Stephen Daniells is the Senior Editor for He has a PhD in chemistry from Queen’s University, Belfast in Northern Ireland, and has worked in research in The Netherlands and France. He has been writing about food science and nutrition for over five years.

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1 comment

clinical trials versus magic numbers

Posted by Gerard Pilley,

"Magic numbers" are irrelevant to women with recurrent UTI.
Only clinical trials according to the gold standard methodology should determine the efficacy of the available brands of cranberries.
Doing a good bibliography gives the answer.

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