Diet drinks may lead to higher breathalyser readings, studies suggest Illustration: Wilcox. It's the guilt-free option that could land you a guilty verdict. Australian research teams studying the metabolism of soft drinks have found mixing artificially sweetened beverages with alcohol results in higher breathalyser readings that could land drivers in court. While only done using small study groups at present, scientists in both Australia and the US have examined links between diet drinks and booze, with results showing a significant disparity between conventional soft drink and diet spin-offs. Chris Irwin, PhD candidate at Griffith University, examined the way the body handles alcohol and dehydration. His study of 16 people repeatedly tested the same group to investigate the link between soft drinks and blood alcohol. It found artificially sweetened drinks provided an average breath alcohol concentration of 0.065 per cent compared to 0.045 per cent for conventionally sugary carbohydrate-laden drinks, just below the legal driving limit of 0.05 per cent. While preliminary, the results could have wide-ranging ramifications if repeated on a larger scale. "There are implications for people that might go and have one or two drinks and if they're choosing drinks that have diet mixers, it might put them over the limit," Irwin said. It may make a big difference in their blood alcohol limit and put them at risk of driving under the influence, while if they have a carbohydrate based drink with alcohol they could be under the limit. The ultimate goal is to try and get that message out. The difference is linked to how the body processes drinks. Sugary beverages take longer to break down, which slows the release of alcohol into the bloodstream. Research thus far into the area has been scarce, but Australia is leading the way. A joint research team comprised of students at the University of Queensland and Griffith University is examining whether different doses of sugars with alcohol have the same effect, and University of Tasmania PhD candidate Amy Peacock is examining similar issues surrounding alcohol and energy drinks. Mr Irwin is ready to publish results from his studies, which also found dehydration has a minimal effect on driver behaviour. The next step is to widen the sample study size and test different volumes and concentrations of soft drink. Mr Irwin's trial saw participants combine one part alcohol with two parts mixer, using around 100ml of vodka and 200ml of ginger beer each time. His study followed a US investigation into the same issue which produced similar results using drinks with higher sugar concentrations. Cecile Marczinski of Northern Kentucky University led a 2012 study that found diet beverages mixed with alcohol produce on average an 18 per cent higher breathalyser result than regular soft drinks. She has prepared follow-up research to further investigate the phenomenon. "The results were pretty surprising," Marczinski said. We are looking at alcohol levels in breath testing at different dose levels with a large sample of men and women. We are also looking at survey data to see if women are more likely to mix diet drinks with alcohol. A spokesman for the Australian Beverages Council said four out of the five best-selling soft drinks in Australia were artificially sweetened, but that it was not possible to say what percentage was sold in licensed venues.