he rise of the superfood began in the 1990s and has grown to include a dizzying array of foods, everything from the Peruvian grain quinoa to the ancient European vegetable kale but not everyone agrees we really need them.
A fruit that can make you thin? That is the gospel according to growers of Australia’s Queen Garnet plum – a “freak” stone fruit with extraordinarily high levels of anthocyanin.
Anthocyanin is the pigment that gives plums, strawberries and blueberries their deep blush.
It is also a class of antioxidant – a compound that reduces oxidative stress in living cells, and which has been investigated for its role in preventing or helping fight disease.
The Queen Garnet came under the spotlight in February when the fruit’s praises were sung by popular ABC TV show Landline.
The programme detailed new research by the University of Southern Queensland (USQ) that produced evidence of the berry’s weight-loss potential.
A flurry of positive rural newspaper reports followed, prompting a rush of consumer interest in the Queen Garnet.
Superfood status can be measured in dollars. Western consumer demand for quinoa, for example, has sent export prices in Peru soaring.
Experts warn that no single food item is a panacea and that there has been a long line of supposed superfoods with health claims that have been found wanting.
The Maqui berry of Chile and the goji berry of China are textbook examples, with producers linking these ancient foods to myriad and sometimes dubious health claims.
The Queen Garnet plum story is a little different. It was accidentally created by plant breeders trying to make a disease-resistant version of the common Japanese plum for the Queensland government a decade ago.
Then researchers at USQ took a closer look at the plum’s positive properties. They fed rats a diet high in fats and carbohydrates until they were obese.
Then they added a few drops of Queen Garnet plum juice to the rats’ drinking water, while exercising the rats half an hour a day. Within eight weeks, the rats had shed most of their excess weight.
That research, coupled with the Queen Garnet’s reputedly deliciously sweet flesh proved a public relations masterstroke for farming co-op Nutrafruit, which paid the Queensland Government for the global license to commercialise the fruit.
But how much weight should be placed on scientific research conducted on rats? USQ Biomedical Sciences Professor Lindsay Brown, who led the research, says the results make a strong case for the Queen Garnet’s health claims and for further funding for human trials.
“All the changes that rats experience with obesity – glucose levels, cardiovascular functions, inflammation – all those occur the same way in humans,” Prof Brown told the BBC, adding: “The plums taste really nice.”
Too good to be true?
However, others are more cautious.
Professor Manny Noakes, research director for nutrition and health at the Australian science agency CSIRO, says it is not a clear-cut case.
“It’s very good research and very interesting research,” says Prof Noakes.
“But when I last checked, humans and rodents were very different. You can feed rats an entire diet to test a hypothesis but that doesn’t mean you’ll get the same results in humans.
“To make a claim that the consumption of a food will make a difference to people’s weight is a pretty long bow to cast.
“Unfortunately, this is something that happens a lot when it comes to promoting the health benefits of food. Similar claims have been made by research on animals using everyday grape seeds.”
SQ’s research on the Queen Garnet was partly funded by the Queensland government. However, consumers need to beware of food manufacturers who publish self-funded scientific research on the weight-loss properties of their products, says Charles Fisher, a principal at food regulatory specialist FoodLegal.
Mr Fisher says about 10 manufacturers have done so since Food Standards Australia New Zealand legalised the practice in 2013.
“From a legal perspective there is a big gap between what consumers understand when they hear the word ‘antioxidant’ and what the scientific reality may be.” he notes.
Critics of cultivated fruit such as the Queen Garnet argue native fruits such as lemon myrtle can deliver even higher levels of anthocyanins.
But Nutrafruit director Hugh Macintosh says indigenous foods are extremely difficult to commercialise.
“There are many fruits out there with high levels of antioxidants but they have to be harvested in the wild so the supply is unreliable, whereas we’ve been growing plums for a long time so know how to do it consistently,” says Mr Macintosh.
“Our plums may not be as sexy as something found in the Amazon but they’re something most of us have been eating all our lives and they have a lot of potential,” the Nutrafruit director adds.0