Fuzzy thinking on fizzy drinks?

27 May 2016

Sir, – Prof Mike Gibney decries fuzzy thinking on the proposed tax on sugar-sweetened drinks (“Tax on fizzy drinks will not deflate obesity problem”, Opinion & Analysis, May 24th). While acknowledging that national and international expert opinion is supportive of the sugar drink tax, he suggests that only nutritional scientists have the requisite expertise to adjudicate on this issue. He argues that sugar-sweetened drinks do not contribute significantly to calorie intakes in adults, that no risk assessment of the proposal has been carried out and that the criteria by which the proposed taxation measure could be deemed successful are unclear. We do not accept these arguments.

While nutritional science clearly has much to contribute to our understanding of overweight and obesity, it is difficult to accept that any scientific discipline (including our own) has a monopoly of insight on the biological, behavioural, environmental and societal forces that have led to the situation where 60 per cent of adults and approximately 25 per cent of children in Ireland (as in other developed countries) are either overweight or obese.

Prof Gibney’s observations on sugar intakes in adults are largely irrelevant as the main focus of the proposed tax is on reducing intakes of sugar-sweetened drinks in children.

In a recent school-based study (the Cork Children’s Lifestyle Study), which collected detailed health, lifestyle, physical activity and dietary data from over 1,000 school children aged eight to 10 years in Cork city and county, we found that the majority (82 per cent) of children were consumers of sugar-sweetened drinks, and these drinks contributed an average of 106 kcal, 135 kcal and 292 kcal per day for normal weight, overweight and obese children respectively. These findings are consistent with emerging evidence from a range of studies, including randomised control trials that show reducing intakes of sugar-sweetened drinks decreases risk of weight gain and obesity in children and young people.

The 2012 “Proposed Sugar-Sweetened Drinks Tax: Health Impact Assessment”, prepared by the Institute for Public Health in Ireland, which reviewed current national and international evidence, estimated that a modest 10 per cent tax would reduce the prevalence of obesity in Ireland by 1.25 per cent.

Not a magic bullet but a potentially significant step forward in the struggle to halt and reverse the obesity epidemic, especially if combined with other measures at the individual and societal level.

How will we assess the impact of the sugar drinks tax, when it is introduced? There is no doubt that this will be challenging, as other factors that influence calorie intakes, and levels of physical activity, will change at the same time.

This is the reality of science and policy development in complex systems, ie the real world, where we have to develop policy and assess its impact on the basis of the best available evidence and often in the teeth of opposition from powerful vested interests, such as those in the food and drinks industry. – Yours, etc,

JANAS HARRINGTON, Senior Lecturer in Public Health Nutrition;

PATRICIA KEARNEY, Professor of Epidemiology,

IVAN J PERRY, Professor of Public Health,

Department of Epidemiology and Public Health, University College Cork