Soda taxes: the arrogance of public health

Posted on October 13, 2015

A couple of articles in the past week in the US, in Time and the New York Times, have revisited Mexico's sugary drinks tax. In January 2014 the government imposed a 10 per cent tax on sugar-sweetened sodas, which are hugely popular in Mexico. Preliminary research suggests consumption fell by six per cent on average over the course of 2014, but the decline in consumption had reached 12 per cent by the end of the year. The soft drinks industry disputes the size of the decline, suggesting a fall in sales of 1.9 per cent.

What impact does such a decline have on calorie intake? If someone were to drink a litre of Coca-Cola per day before the tax and then drank 12 per cent less afterwards, the effect would be a less-than-impressive 50 calories a day – about two per cent of an adult male's calorie intake for a day. Even assuming that none of those calories are replaced with calories from other drinks, such a small fall in calorie intake would have a negligible impact on body weight. If those calories were replaced with fruit juice, which is full of natural sugar, then the effect on obesity would be zero.

Two other things become clear reading about the Mexican soda tax. The first is that it is regressive: the poor cut their consumption significantly more than everyone else simply because they couldn't afford the new prices. Second, the reasons why people cut down substantially on sugar in their food and drink have much more to do with a desire to lose weight or to eat more healthily than with taxation. They chose to change their habits for their own personal reasons, not because the government nudged them to do so. Leaving these choices up to individuals is far more powerful than governments wading in.

Still, as we have seen so many times before in relation to tobacco and alcohol, that won't stop campaigners and activist researchers from pushing the agenda of higher taxation. Their outlook was neatly summed up by one of the most prominent American researchers on soda taxes, Barry Popkin: 'It is a little paternalistic, in the sense saying that we know better but at the same time it is going to benefit them.'

Those Mexicans who find their pockets a little emptier might not agree that they have benefited from the lobbying of Popkin and friends, but that won't stop nannying campaigners, celebrities and politicians on this side of the pond from presenting sugar taxes as a cure-all for obesity.