The consumption of sugar has trebled worldwide over the past 50 years, closely tracking the obesity curve and significantly increasing the risk of liver damage, pancreatic cancer, type 2 diabetes and heart disease. Researchers at Oxford University have calculated that a 20% tax on sugary soft drinks would cut obesity levels by around 400,000.
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Oliver T Mytton, Dushy Clarke, Mike Rayner (2012). Taxing unhealthy food and drinks to improve health. BMJ.344:e293