Sweet and sour

Public health initiatives, such as those being considered in the UK around sugar, carry risks as well as potential benefits for any government. The first consequence of action is the near-certain accusation of presiding over a nanny state. Although the archetypal nanny, Mary Poppins, was famously enamoured with sugar's ability to help the medicine go down, nowadays, most debate is around whether it actually sends our societal need for medicine in the opposite direction. Is sugar a particular driver of mortality and morbidity that merits state intervention? The World Health Organisation seems to think so, with it's recent report on Ending Childhood Obesity making an unequivocal call for effective taxes on sugar-sweetened beverages.

What's a politician to do? Tax increases number among the most controversial of policy decisions. Making sugar or sugar-sweetened beverages subject to a "sin tax" risks unpopularity not just with the industry but also with voting consumers. On a European level, some initiatives have already fallen foul of practical and legislative problems, while others are yet to yield evidence on health. The concept is especially discomfiting where a governing party ideologically favours the reduction of existing taxes rather than the addition of new ones. Even where the evidence base is beyond dispute, taxes come with winners and losers, with health benefits sure to lag the intervention and be difficult to attribute. Recognition may take many years to arrive, if it ever does.

So, what evidence might be used to justify a sugar tax? Well, we know beyond dispute that sugar is energy-dense, but otherwise nutritionally empty. We know that excess energy intake contributes to obesity, and that obesity markedly increases the risk of developing type-2 diabetes. From here on in things become surprisingly controversial. Some researchers claim calories from sugar represent a specific driver for diabetes itself, and cite studies examining the impact of calorically matched sugar replacement on children with metabolic syndrome as proof. Other researchers refute this concept, claiming a calorie is merely a calorie, however it is packaged. Commentators on all sides agree however, given the lack of nutritional value, if you want to reduce energy intake, sugar is a fairly obvious place to start. Indeed, the advice to UK government from Public Health England was for action on a number of fronts including a 10-20% levy on high-sugar products.

Whilst isolating the impact of obesity on longevity is proving more complex than previously expected, research consistently shows type-2 diabetes to be associated with a range of other diseases, and it is estimated by Diabetes UK to reduce life expectancy by up to ten years. Diabetes globally is one of the top-ten causes of death, and so the fact that the variant usually associated with aging is growing amongst children is a cause for serious concern.

When deciding on health interventions it is clearly preferable to be guided by definitive evidence, preferably by demonstrable positive impacts within comparable economies. Such data, however, is thin on the ground. Much has been made of Mexico's recent sugar levy, but the experience of a soda tax in a country with a history of potable water problems is tricky to extrapolate. Indeed, no two countries face precisely the same challenges, so an element of judgement is always required. The early movers in public health are vital, in that they expand the evidence base that informs future political decisions elsewhere. For a tax that may greatly impact lollipops and fizzy-drinks, it is ironic that some governments will simply have to suck-it-and-see...