Drinking fruit juice as a substitute for fruits could be counter-productive due to its high sugar content, researchers at the University of Glasgow have warned.

Writing in The Lancet Diabetes and Endocrinology journal, Professor Naveed Sattar and Dr. Jason Gill both of the University of Glasgow’s Institute of Cardiovascular and Medical Sciences, call for better labelling of fruit juice containers to make explicit to consumers that they should drink no more than 150ml a day.

They also recommend a change to the U.K. Government’s current five-a-day guidelines, saying these five fruit and vegetable servings should no longer include a portion of fruit juice.

Inclusion of fruit juice as a fruit equivalent is probably counter-productive because it fuels the perception that drinking fruit juice is good for health, and thus need not be subject to the limits that many individuals impose on themselves for consumption of less healthy foods.

Professor Sattar, who is Professor of Metabolic Medicine, said, “Fruit juice has a similar energy density and sugar content to other sugary drinks, for example: 250ml of apple juice typically contains 110 kcal and 26g of sugar; and 250ml of cola typically contains 105kcal and 26.5g of sugar.”

“Additionally, by contrast with the evidence for solid fruit intake, for which high consumption is generally associated with reduced or neutral risk of diabetes, current evidence suggests high fruit juice intake is associated with increased risk of diabetes.

“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,” Sattar said.

Although fruit juices contain vitamins and minerals, whereas sugar-sweetened drinks do not, Gill argues that the micronutrient content of fruit juices might not be sufficient to offset the adverse metabolic consequences of excessive fruit juice consumption.

“In one scientific trial, for example, it was shown that, despite having a high antioxidant content, the consumption of half a litre of grape juice per day for three months actually increased insulin resistance and waist circumference in overweight adults,” Gill said.

“Thus, contrary to the general perception of the public, and of many healthcare professionals, that drinking fruit juice is a positive health behaviour, their consumption might not be substantially different in health terms than drinking other sugary drinks,” he said.