Two medical researchers writing in one of The Lancet journals argue that because of its high sugar content, fruit juice could be just as bad for us as sugar-sweetened beverages like carbonated drinks and sodas.
Naveed Sattar, professor of Metabolic Medicine, and Dr. Jason Gill, both of the Institute of Cardiovascular and Medical Sciences at the University of Glasgow in Scotland, call for the UK government to change the current "five a day" guideline to exclude a portion of fruit juice from the list of fruits and vegetable servings that count toward it.
In their paper, published in the The Lancet Diabetes & Endocrinology, they propose that including fruit juice as one of the five a day is "probably counter-productive," because it leads people to consider fruit juice as a healthy food that does not need to be limited, as is the case with less healthy foods.
They also urge food companies to improve container labeling of fruit juices to inform consumers they should drink no more than 150 ml a day of the product.
Fruit juice has come under the spotlight since medical experts recently started looking more closely at the link between high sugar intake and the risk for heart disease.
In 2012, researchers at Harvard reported in the journal Circulation that daily consumption of sugary drinks raised heart disease risk in men. Two years earlier, researchers presenting at an American Heart Association conference said Americans' higher consumption of sugary drinks has led to more diabetes and heart disease over the past decade.
Fruit juice is not a low-sugar alternative to sugar-sweetened drinks
Dr. Gill says "there seems to be a clear misperception that fruit juices and smoothies are low-sugar alternatives to sugar-sweetened beverages."
Prof. Sattar explains:
"Fruit juice has a similar energy density and sugar content to other sugary drinks, for example: 250 ml of apple juice typically contains 110 kcal and 26 g of sugar; and 250 ml of cola typically contains 105 kcal and 26.5 g of sugar."
He says research is beginning to show that unlike solid fruit intake, for which high consumption appears linked either to reduced or neutral risk for diabetes, high fruit juice intake is linked to raised risk for diabetes.
"One glass of fruit juice contains substantially more sugar than one piece of fruit."
"One glass of fruit juice contains substantially more sugar than one piece of fruit; in addition, much of the goodness in fruit - fibre, for example - is not found in fruit juice, or is there in far smaller amounts," he adds.
Also, although fruit juices contain vitamins and minerals that are mostly absent in sugar-sweetened drinks, the levels of nutrients in fruit juices many not be enough to offset the unhealthy effect that excessive consumption has on metabolism, says Dr. Gill.
In their paper they refer to a trial where participants drank half a liter of pure grape juice every day for 3 months. And the results showed that despite grape juice's high antioxidant properties, it led to increased insulin resistance and bigger waists in overweight adults.
Poor public awareness about the amount of sugar in fruit juice
The researchers also report an online poll of over 2,000 adults that tested public awareness of the sugar content of fruit juices. Respondents were asked to look at pictures of containers filled with non-alcoholic drinks and estimate how many teaspoons of sugar each contained.
The results showed that even though all the drinks had a similar sugar content, on average the respondents underestimated the sugar content of fruit juices and smoothies by 48%, and overestimated that of carbonated drinks by an average of 12%.
Prof. Sattar says there are strong public health reasons for taxing or targeting sugary drinks in some way, so as to reduce consumption. But he and Dr. Gill do not go as far as to advocate children should not drink fruit juice at all, which is what some have been calling for in the US.
They do, however, urge public health policymakers to include fruit juice when they debate the issue of sugar-sweetened drinks.