04.Our response to industry criticism
The superfruit juice industry is fighting back after CHOICE awarded a Shonky award to superjuices in December 2007.
You may have heard criticism of CHOICE’s tests on superjuices and our approach to the science. We stand behind our test method and findings. Here are the key facts in defence of our position:
CHOICE tested the antioxidants in the juices (using a measure called ORAC) because that’s what most of the juice manufacturers talk about in their marketing.
The one message that consistently stood out in the marketing literature for superfruits in general was the claim of their superior antioxidant capacity. The total antioxidant capacity (TAC) can be measured using an ORAC (oxygen radical absorbance capacity) test.
The testing allowed CHOICE to compare the TAC of a serve of superjuice (the ones we’d purchased were tested to provide examples) with serves of more common fruits. We used the TAC of a red delicious apple as a point of reference given that it’s a relatively cheap fruit, that’s commonly available in Australian supermarkets and greengrocers.
Total antioxidant capacity is just one feature of superfruits, however. A high antioxidant score doesn’t necessarily guarantee benefits in the body. In addition, antioxidant capacity can also be artificially boosted by preservatives (which can have antioxidant activity) that are sometimes present in superfruit juices.
This means that for some of the juices, the antioxidant capacity attrituable to the preservative-free component could actually be somewhat lower than the total antioxidant capacity of the product as a whole which we reported.
CHOICE carefully sought out and assessed the medical literature on the various superfruits and their components. Some evidence has greater weight than other evidence – it’s not just about the number of published studies, but their quality and findings.
Our research wasn’t restricted to testing antioxidant capacity. CHOICE also looked at the claims made in both generic marketing material and for specific products, where present. Some products place more emphasis on the benefit of specific components of the fruit. Examples include xanthones (in mangosteen) and polysaccharides (in goji).
CHOICE used the PubMed database (from the US National Library of Medicine and National Institutes of Health) to conduct a search for studies on superfruits and their products that have been published in the scientific literature. This included evidence for specific components of superfruits. We then assessed the evidence in a thorough and scientifically rigorous way.
Two highly respected Australian bodies, the National Health and Medical Research Council (NHMRC) and Food Standards Australia and New Zealand (FSANZ) have developed frameworks for assessing the quality of scientific evidence. In both these frameworks, the highest level of evidence is from systematic reviews of intervention studies, such as randomised controlled trials.
This is followed by randomised controlled trials themselves, cohort studies and case control studies, and then finally experimental studies (cellular and animal studies).
As we state in this report, some of the results of published studies on superfruits are promising. But there are few clinical trials, and what happens in a test tube or animal may not occur in humans. CHOICE would be interested in seeing more good quality research being carried out on superfruits. But our current position on superfruit juices is framed taking the totality of evidence into account, for the fruits as well as fruit components, rather than on the basis of individual studies.